Determining properties of contact between catheter tip and tissue

文档序号：1449196 发布日期：2020-02-18 浏览：17次中文

阅读说明：本技术 确定导管尖端与组织之间接触的性质 (Determining properties of contact between catheter tip and tissue ) 是由 J·V·克布雷斯 D·全 J·E·约翰逊于 2018-04-26 设计创作，主要内容包括：本文公开了用于促进评估消融导管的电极组件与活体组织之间的接触的性质的系统和方法。在一些实施例中,方法包括获得第一电极和第二电极之间的第一检测电压、获得第二电极和第三电极之间的第二检测电压,其中第一电极和第二电极沿着消融导管的电极组件定位,并且其中第一电极在第二电极的远侧,第三电极位于第二电极的近侧。(Disclosed herein are systems and methods for facilitating evaluation of properties of contact between an electrode assembly of an ablation catheter and living tissue. In some embodiments, the method includes obtaining a first detected voltage between the first electrode and the second electrode, obtaining a second detected voltage between the second electrode and the third electrode, wherein the first electrode and the second electrode are positioned along an electrode assembly of the ablation catheter, and wherein the first electrode is distal to the second electrode and the third electrode is proximal to the second electrode.)

1. A method for facilitating assessment of a property of contact between an electrode assembly of an ablation catheter and living tissue, the method comprising:

obtaining a first detected voltage between a first electrode and a second electrode, wherein the first electrode and the second electrode are positioned along an electrode assembly of the ablation catheter, and wherein the first electrode is distal to the second electrode;

obtaining a second detection voltage between the second electrode and a third electrode, the third electrode being proximal to the second electrode;

making a first comparison between the first detected voltage and a first threshold voltage, wherein the first threshold voltage is indicative of contact between living tissue and a first portion of the ablation catheter located at a position between the first electrode and the second electrode; and

making a second comparison between the second detected voltage and a second threshold voltage, wherein the second threshold voltage is indicative of contact between living tissue and a second portion of the ablation catheter located at a position between the second electrode and the third electrode;

wherein contact between living tissue and the first portion of the ablation catheter is confirmed if the first voltage is equal to or higher than the first threshold voltage; and is

Wherein contact between the living tissue and the second portion of the ablation catheter is confirmed if the second voltage is equal to or higher than the second threshold voltage.

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of a red light source, a green light source, and a blue light source,

further comprising displaying a level of contact between the electrode assembly and the living tissue on the graphical representation of the electrode assembly;

wherein the first threshold voltage is the same as the second threshold voltage;

wherein at least one of the first threshold voltage and the second threshold voltage is 0.30 mV;

wherein displaying on the graphical representation of the electrode assembly a level of contact of the electrode assembly with living tissue comprises: a halo or other visual covering comprising the graphical representation surrounding the electrode assembly; and is

Wherein the halo or other visual overlay comprises at least one parameter related to the strength of contact between the electrode assembly and living tissue.

3. The method of claim 1, wherein the first and second light sources are selected from the group consisting of a red light source, a green light source, and a blue light source,

further comprising displaying a level of contact between the electrode assembly and the living tissue on the graphical representation of the electrode assembly;

Wherein the halo or other visual overlay comprises at least one parameter related to the strength of contact between the electrode assembly and living tissue.

4. The method of claim 1, wherein the first threshold voltage is the same as the second threshold voltage.

5. The method of claim 1, wherein at least one of the first threshold voltage and the second threshold voltage is 0.30 mV.

6. The method of claim 1, wherein at least one of the first threshold voltage and the second threshold voltage is between 0.2mV and 0.4 mV.

7. The method of claim 1, further comprising displaying a level of contact between the electrode assembly and living tissue on the graphical representation of the electrode assembly.

8. The method of claim 7, wherein displaying the level of contact of the electrode assembly with living tissue on the graphical representation of the electrode assembly comprises: including a halo or other visual covering around the graphical representation of the electrode assembly.

9. The method of claim 8, wherein the halo or other visual overlay comprises at least one parameter related to the strength of contact between the electrode assembly and living tissue.

10. The method of claim 9, wherein the at least one parameter of the halo or other visual overlay comprises at least one of: size, shape, color, intensity, shading, brightness, contrast, and texture.

11. The method of claim 1, further comprising making a determination related to an orientation of the electrode assembly relative to living tissue.

12. The method of claim 11, wherein making a determination regarding an orientation of the electrode assembly relative to living tissue comprises comparing the first comparison to the second comparison.

13. The method of claim 11, wherein a determination that the electrode assembly is in a parallel orientation with respect to living tissue is made when the first detected voltage is equal to or greater than the first threshold voltage, the second detected voltage is equal to or greater than the second threshold voltage, and the first detected voltage and the second detected voltage are within a threshold percentage difference of each other.

14. The method of claim 13, wherein the threshold percentage difference is 0-10%.

15. The method of claim 11, wherein a determination that the electrode assembly is in a vertical orientation with respect to living tissue is made when the first detected voltage is equal to or higher than the first threshold voltage and the second detected voltage is lower than the second threshold voltage.

16. The method of claim 1, wherein the first electrode comprises a distal tip electrode member and a second electrode is spaced apart from the first electrode by a first gap distance, wherein the first electrode and the second electrode are electrically coupled by a filtering element to form a composite tip electrode assembly.

17. The method of claim 16, wherein the first gap distance is 0.5 mm.

18. The method of claim 16, wherein the first gap distance is between 0.1mm and 1 mm.

19. The method of claim 1, wherein the third electrode comprises a ring electrode.

20. The method of claim 19, wherein the second electrode is separated from the third electrode by a second gap distance.

21. The method of claim 20, wherein the second gap distance is 1 mm.

22. The method of claim 20, wherein the second gap distance is between 0.5mm and 2 mm.

23. The method of any one of the preceding claims, further comprising displaying a real-time temperature of the electrode assembly.

24. The method of claim 23, wherein displaying the real-time temperature of the electrode assembly comprises a graphical representation.

25. The method of claim 24, wherein the graphical representation of the temperature comprises a color-coded representation displayed to a user.

26. The method of any of the preceding claims, further comprising providing a visual indication to a user of the status of ablation progress.

27. The method of claim 26, wherein at least in part using (i) at least one of (a) the first comparison between the first detected voltage and the first threshold voltage and (b) the second comparison between the second detected voltage and the second threshold voltage, and (ii) a temperature of the electrode assembly, is determined to provide a visual indication.

28. The method of claim 26, wherein providing a visual indication comprises displaying a graphical representation on an output indicating the status of the ablation.

29. The method of claim 28, wherein the graphical representation comprises a frame or peripheral border surrounding the graphical representation of the electrode assembly.

30. The method of claim 29, wherein the frame or peripheral boundary is configured to change color.

31. The method of claim 29, wherein the frame or peripheral boundary is configured to change color to inform a user of one or more of: (i) energy delivery to the ablation assembly has not been initiated, (ii) energy delivery to the ablation assembly has been initiated but lesion formation has not begun, (iii) energy delivery to the ablation assembly has been initiated and lesion formation has begun, (iv) energy delivery to the ablation assembly has been initiated and completion of the lesion formation is near completion, (v) energy delivery to the ablation assembly has been initiated and completion of the lesion formation is completed.

32. A system for ablating tissue and facilitating assessment of a property of contact between an electrode assembly of an ablation catheter and living tissue, the system comprising:

an ablation catheter;

an electrode assembly; and

at least one additional electrode;

wherein the system is configured to obtain a first detected voltage between a first electrode and a second electrode, wherein the first electrode and the second electrode are positioned along the electrode assembly of the ablation catheter, and wherein the first electrode is distal to the second electrode;

wherein the system is configured to obtain a second detected voltage between the second electrode and the at least one additional electrode, the at least one additional electrode being proximal to the second electrode;

wherein the system is configured to make a first comparison between the first detected voltage and a first threshold voltage, wherein the first threshold voltage is indicative of contact between living tissue and a first portion of the ablation catheter located at a position between the first electrode and the second electrode;

wherein the system is configured to make a second comparison between the second detected voltage and a second threshold voltage, wherein the second threshold voltage is indicative of contact between living tissue and a second portion of the ablation catheter located at a position between the second electrode and the at least one additional electrode;

wherein contact between living tissue and the first portion of the ablation catheter is confirmed if the first voltage is equal to or higher than the first threshold voltage; and is

Wherein contact between the living tissue and the second portion of the ablation catheter is confirmed if the second voltage is equal to or higher than the second threshold voltage.

33. The system of claim 32, wherein the first and second sensors are arranged in a single unit,

further comprising a display configured to display a level of contact between the electrode assembly and living tissue on a graphical representation of the electrode assembly;

wherein the first threshold voltage is the same as the second threshold voltage;

wherein at least one of the first threshold voltage and the second threshold voltage is 0.30 mV;

Wherein the halo or other visual overlay comprises at least one parameter related to the strength of contact between the electrode assembly and living tissue.

34. The system of claim 32, wherein the first and second sensors are arranged in a single unit,

further comprising a display configured to display a level of contact between the electrode assembly and living tissue on a graphical representation of the electrode assembly;

Wherein the halo or other visual overlay comprises at least one parameter related to the strength of contact between the electrode assembly and living tissue.

35. The system of claim 32, wherein the first threshold voltage is the same as the second threshold voltage.

36. The system of claim 32, wherein at least one of the first threshold voltage and the second threshold voltage is 0.30 mV.

37. The system of claim 32, wherein at least one of the first threshold voltage and the second threshold voltage is between 0.2mV and 0.4 mV.

38. The system of claim 32, wherein the system is configured to display a level of contact between the electrode assembly and living tissue on the graphical representation of the electrode assembly.

39. The system of claim 38, wherein displaying on the graphical representation of the electrode assembly a level of contact of the electrode assembly with living tissue comprises: including a halo or other visual covering around the graphical representation of the electrode assembly.

40. The system of claim 39, wherein the halo or other visual overlay comprises at least one parameter related to an intensity of contact between the electrode assembly and living tissue.

41. The system of claim 40, wherein the at least one parameter of the halo or other visual overlay comprises at least one of: size, shape, color, intensity, shading, brightness, contrast, and texture.

42. The system of claim 32, wherein the system is configured to make a determination related to an orientation of the electrode assembly relative to living tissue.

43. A system as in claim 42, wherein making a determination related to an orientation of the electrode assembly relative to living tissue comprises comparing the first comparison to the second comparison.

44. The system of claim 42, wherein a determination that the electrode assembly is in a parallel orientation with respect to living tissue is made when the first detected voltage is equal to or greater than the first threshold voltage, the second detected voltage is equal to or greater than the second threshold voltage, and the first detected voltage and the second detected voltage are within a threshold percentage difference of each other.

45. The system of claim 44, wherein the threshold percentage difference is 0-10%.

46. The system of claim 42, wherein a determination that the electrode assembly is in a vertical orientation with respect to living tissue is made when the first detected voltage is equal to or above the first threshold voltage and the second detected voltage is below the second threshold voltage.

47. The system of claim 32, wherein the first electrode comprises a distal tip electrode member and a second electrode is spaced apart from the first electrode by a first gap distance, wherein the first electrode and the second electrode are electrically coupled by a filtering element to form a composite tip electrode assembly.

48. The system of claim 47, wherein the first gap distance is 0.5 mm.

49. The system of claim 47, wherein the first gap distance is between 0.1mm and 1 mm.

50. The system of claim 32, wherein the third electrode comprises a ring electrode.

51. The system of claim 50, wherein the second electrode is separated from the third electrode by a second gap distance.

52. The system of claim 51, wherein the second gap distance is 1 mm.

53. The system of claim 51, wherein the second gap distance is between 0.5mm and 2 mm.

54. The system of any one of claims 33 to 53, wherein the system is configured to provide a real-time temperature of the electrode assembly on the display.

55. The system of claim 54, wherein displaying the real-time temperature of the electrode assembly comprises a graphical representation.

56. The system of claim 55, wherein the graphical representation of the temperature comprises a color-coded representation displayed to a user.

57. The system of any one of claims 32 to 56, wherein the system is configured to provide a visual indication of the status of ablation progress to a user on the display.

58. The system of claim 57, wherein at least in part (i) at least one of (a) the first comparison between the first detected voltage and the first threshold voltage and (b) the second comparison between the second detected voltage and the second threshold voltage, and (ii) a temperature of the electrode assembly is determined to be provided with a visual indication.

59. The system of claim 57, wherein providing a visual indication comprises displaying a graphical representation on an output indicating the status of the ablation.

60. The system of claim 59, wherein the graphical representation includes a frame or peripheral border surrounding the graphical representation of the electrode assembly.

61. A method for facilitating assessment of a property of contact between a distal tip of an ablation catheter and body tissue, the method comprising:

generating an output indicative of a property of contact between a distal end portion of an ablation catheter and body tissue based on bipolar measurements between electrode members prior to applying ablation power to the body tissue using the ablation catheter,

wherein the electrode members comprise a distal tip electrode member and a proximal electrode member, the distal tip electrode member and the proximal electrode member being spaced apart by a gap distance and electrically coupled by a filtering element to form a composite tip electrode assembly; and

generating an output indicative of a property of the contact between the distal portion of the ablation catheter and body tissue based on temperature readings obtained from a plurality of temperature sensors positioned along the distal portion of the ablation catheter,

wherein the plurality of temperature sensors comprises a first plurality of temperature sensors positioned along a distal face of the distal tip electrode member and a second plurality of temperature sensors located at or adjacent to a proximal end of the proximal electrode member.

62. The method of claim 61, wherein the bipolar measurements comprise bipolar impedance measurements.

63. The method of claim 61, further comprising a third electrode proximally spaced from the proximal electrode member of the composite tip electrode assembly.

64. The method of claim 61, wherein generating an output indicative of a property of the contact between the distal end portion of ablation catheter and the body tissue based on bipolar measurements between electrode members comprises:

obtaining bipolar voltage measurements indicative of local tissue voltage between each of three pairs of combinations of the distal tip electrode member, the proximal electrode member, and the third electrode; and

determining whether an orientation of the distal portion of the ablation catheter relative to the body tissue is parallel or perpendicular based at least in part on the obtained bipolar voltage measurements,

wherein the output indicative of a property of the contact between the distal end portion of the ablation catheter and body tissue based on bipolar measurements between the electrode members comprises a graphical representation of the distal end portion of the ablation catheter in the determined orientation.

65. The method of claim 64, wherein determining whether the orientation of the distal end portion of the ablation catheter relative to the body tissue is parallel or perpendicular comprises: comparing the bipolar voltage measurement between the distal tip electrode member and the proximal electrode member of the composite tip electrode assembly with the bipolar voltage measurement between the proximal electrode member and the third electrode of the composite tip electrode assembly, wherein the orientation is determined to be parallel if both bipolar voltage measurements are substantially equal, and perpendicular otherwise.

66. The method of claim 64, wherein the system is configured to convert the obtained voltage measurements from a time domain to a frequency domain to calculate a frequency measurement corresponding to each of the obtained voltage measurements, wherein the step of determining whether the orientation of the distal portion of the ablation catheter relative to the body tissue is parallel or perpendicular is based at least in part on the frequency measurements.

67. The method of any one of claims 64 to 66, further comprising: generating an output that displays a current maximum voltage measurement of the obtained voltage measurements, wherein the current maximum voltage measurement comprises one of a maximum amplitude and a maximum pulse width or a combination of a maximum amplitude and a maximum pulse width.

68. The method of claim 66 or 67, further comprising generating an output that displays a current maximum frequency measurement of the calculated frequency measurements.

69. The method of any one of claims 64 to 68, further comprising: generating an output indicative of completion of lesion formation when it is determined that the magnitude of the maximum voltage measurement is no longer changing over time.

70. The method of any one of claims 61 to 69, wherein generating an output indicative of a property of the contact between the distal portion of the ablation catheter and body tissue based on temperature readings comprises: generating a graphical representation of the distal portion of the ablation catheter for display on a display device operatively coupled to the ablation catheter.

71. The method of claim 70, wherein the graphical representation of the distal portion of the ablation catheter comprises a two-dimensional image.

72. The method of claim 70, wherein the graphical representation of the distal portion of the ablation catheter comprises a three-dimensional image.

73. The method of claim 70, wherein the graphical representation of the distal portion of the ablation catheter includes separate zones corresponding to a general area on the ablation catheter surrounding each of the first plurality of temperature sensors and each of the second plurality of temperature sensors.

74. The method of claim 73, wherein generating an output indicative of a property of the contact between the distal portion of the ablation catheter and body tissue based on temperature readings comprises: associating a color with each of the temperature readings and filling each of the zones with the color.

75. The method of claim 70, wherein generating an output indicative of a property of the contact between the distal portion of the ablation catheter and body tissue based on temperature readings comprises: determining temperature values at a plurality of locations along the distal portion of the ablation catheter, correlating colors with the temperature values at the plurality of locations and generating pixels having the colors for the plurality of locations.

76. The method of claim 75, further comprising: interpolating temperature values at locations between the plurality of locations, associating a color with each of the interpolated temperature values, and generating a pixel having the color.

77. The method of claim 74, wherein associating a color with each of the temperature readings comprises: determining a stored color value associated with a value of each of the temperature readings.

78. The method of any one of claims 70 to 77, further comprising: generating, for display, an output indicative of the determined orientation of the distal portion of the ablation catheter relative to the body tissue.

79. The method of any one of claims 70 to 77, further comprising: an alarm is generated if one of the temperature readings exceeds a threshold temperature.

80. The method of any one of claims 70 to 77, further comprising: storing the following outputs in a memory: indicating a property of the contact at one or more instances in time when ablation power having a frequency in an ablation frequency range is applied to the composite-tip electrode assembly.

81. The method of claim 80, further comprising: storing output indicative of the determined orientation at the one or more time instances in a memory.

82. A method for displaying a visual representation to facilitate contact assessment during an ablation procedure, the method comprising:

obtaining temperature data from a first plurality of temperature sensors located at a distal tip of an ablation catheter and from a second plurality of temperature sensors spaced apart from the first plurality of temperature sensors along the ablation catheter for a period of time during which ablation energy is being applied to tissue by the ablation catheter;

generating a visual representation for display on a display device operatively coupled to the ablation catheter, wherein the visual representation includes graphical information indicative of the temperature data obtained from the first and second pluralities of temperature sensors,

wherein the graphical information comprises a color output indicative of temperature data for each of the first plurality of temperature sensors and each of the second plurality of temperature sensors, and

wherein the visual representation is further indicative of an orientation of the distal tip of the ablation catheter relative to the tissue determined based on the temperature data.

83. The method of claim 82, wherein the method is performed continuously while ablation energy is applied to the tissue by the ablation catheter.

84. The method of claim 82 or 83, wherein the visual representation comprises a graphical image of a distal portion of the ablation catheter.

85. The method of claim 84, wherein the graphical image is a two-dimensional image.

86. The method of claim 84, wherein the graphical image is a three-dimensional image.

87. The method of any one of claims 82 to 86, wherein the graphical image of the distal portion of the ablation catheter is adapted to rotate to indicate a real-time orientation of the ablation catheter relative to the tissue, wherein the orientation is determined based on the temperature data.

88. The method of any of claims 82 to 87, wherein the colour output varies in colour for different values of the temperature data so as to provide a visual representation of the current temperature level associated with each of the temperature sensors.

89. The method of any one of claims 82 to 88, further comprising: storing the visual representation or information implied by the visual representation in a memory for later access.

90. A method for indicating a property of contact between a distal portion of an ablation catheter and body tissue, the method comprising:

determining whether ablation energy is being delivered to the body tissue by the ablation catheter;

if it is determined that the ablation energy is not being delivered:

obtaining bipolar voltage measurements indicative of local tissue voltage between pairs of spaced-apart electrodes positioned along the distal end portion of the ablation catheter, wherein the spaced-apart electrodes include a distal electrode member of a composite-tip electrode assembly located at a distal tip of the ablation catheter, a proximal electrode member of the composite-tip electrode assembly positioned along the ablation catheter and proximally spaced apart from the distal electrode member by a gap, and a third electrode member proximally spaced apart from the proximal electrode member of the composite-tip electrode member; and is

Generating an output indicative of a property of contact between the distal portion of the ablation catheter and the body tissue based at least in part on the bipolar voltage measurement;

if it is determined that ablation energy is being delivered to the body tissue by the ablation catheter, then:

receiving signals from a plurality of temperature sensors spaced apart from one another along a length of the ablation catheter, the signals including real-time temperature data for each of the plurality of temperature sensors;

calculating a temperature measurement for each of the plurality of temperature sensors from the real-time temperature data; and is

Generating a graphical representation of the distal portion of the ablation catheter including outputs indicative of the calculated temperature measurements for each of the temperature sensors.

91. The method of claim 90, wherein the plurality of temperature sensors comprises:

a first plurality of temperature sensors positioned along a distal face of the distal electrode member of the composite tip electrode assembly; and

a second plurality of temperature sensors positioned along or near an end of the proximal electrode member of the composite tip electrode assembly.

92. The method of claim 90 or 91, wherein the graphical representation of the distal portion of the ablation catheter includes a color output indicative of a current temperature associated with each of the temperature sensors based on the calculated temperature measurements, wherein the color output changes in color from light to dark as the temperature value of the calculated temperature measurements increases.

93. The method of any of claims 90 to 92, further comprising causing the graphical representation of the distal end portion of the ablation catheter to be rotated to indicate a current orientation of the distal end portion relative to the body tissue, wherein the current orientation is determined based on the calculated temperature measurement.

94. The method of any of claims 90 to 93, further comprising storing information indicative of the calculated temperature measurements at one or more instances in time when ablation energy is being delivered by the ablation catheter in a memory.

95. A method for indicating a property of contact between a distal tip of an ablation catheter and body tissue, the method comprising:

determining whether ablation energy is being delivered to the body tissue by the ablation catheter;

if it is determined that the ablation energy is not being delivered:

obtaining a bipolar impedance value between two electrode members of a composite tip electrode assembly, wherein the composite tip electrode assembly includes a distal electrode member located at a distal tip of the ablation catheter, a proximal electrode member located along the ablation catheter and proximally spaced apart from the distal electrode member by a gap; and is

Outputting a contact indication value indicating a contact level based on the bipolar impedance value;

if it is determined that ablation energy is being delivered to the body tissue by the ablation catheter, then:

calculating a temperature measurement for each of the plurality of temperature sensors from the real-time temperature data; and is

Outputting, for display on a display device, a graphical user interface including information indicative of the calculated temperature measurements for each of the temperature sensors.

96. The method of claim 95, wherein the bipolar impedance value comprises a component of a complex impedance between the two electrode members.

97. The method of claim 96, wherein the components of the complex impedance include amplitude and phase angle.

98. The method of any one of claims 95 to 97, wherein the plurality of temperature sensors comprises:

a first plurality of temperature sensors positioned along a distal face of the distal electrode member of the composite tip electrode assembly; and

a second plurality of temperature sensors positioned along or near an end of the proximal electrode member of the composite tip electrode assembly.

99. The method of any of claims 95 to 98, wherein outputting a graphical user interface for display on a display device comprises: generating a visual representation of the distal tip of the ablation catheter, wherein the visual representation includes separate zones corresponding to each of the temperature sensors.

100. The method of claim 99, wherein each of the separate zones comprises a color indicative of a current temperature associated with each of the temperature sensors based on the calculated temperature measurements.

101. The method of claim 99 or 100, further comprising causing the visual representation of the distal tip of the ablation catheter to be rotated to indicate a current orientation of the distal tip relative to the body tissue, wherein the current orientation is determined based on the calculated temperature measurement.

102. The method of any of claims 99 to 101, wherein the step of outputting a graphical user interface for display on a display device further comprises: outputting a visual representation of the plane of the body tissue.

103. The method of claim 102, wherein the step of outputting a graphical user interface for display on a display device further comprises: outputting a visual representation indicative of a property of a predicted lesion underlying the visual representation of the plane of the body tissue based at least in part on the determined orientation of the distal tip relative to the body tissue and the calculated temperature measurement.

104. The method of claim 103, wherein the visual representation indicative of a property of a predicted lesion comprises an outline of a boundary of the predicted lesion.

105. The method of any of claims 99 to 104, further comprising storing information indicative of the calculated temperature measurements at one or more instances in time when ablation energy is being delivered by the ablation catheter in a memory.

106. A method for indicating a property of contact between a distal tip of an ablation catheter and body tissue based, at least in part, on temperature measurements received from a plurality of temperature sensors spaced apart along a length of the ablation catheter, the method comprising:

receiving signals from a plurality of temperature sensors spaced apart from each other along a length of the ablation catheter;

calculating a temperature measurement for each of the temperature sensors from the received signals; and

outputting, for display, a graphical user interface including information indicative of the calculated temperature measurements for each of the temperature sensors,

wherein the information indicative of the calculated temperature measurements facilitates determining a property of the contact between the distal tip of the ablation catheter and the body tissue.

107. A system for generating an output to facilitate determining a property of contact between a medical instrument and body tissue during an ablation procedure, the system comprising:

an ablation catheter, the ablation catheter comprising:

a compound tip electrode comprising a distal tip electrode member and a proximal electrode member spaced apart from the distal tip electrode member by a gap distance;

a first plurality of temperature sensors positioned along a distal face of the distal tip electrode member and configured to obtain data indicative of a temperature of each of the first plurality of temperature sensors; and

a second plurality of temperature sensors positioned along the ablation catheter at or near the proximal end of the proximal electrode member and configured to obtain data indicative of a temperature of each of the second plurality of temperature sensors;

a graphical user interface system comprising at least one processing device configured to receive data indicative of the temperature of each of the first plurality of temperature sensors and each of the second plurality of temperature sensors and generate a graphical output for display on a display device operatively connected to the at least one processing device, wherein the graphical output comprises a visual representation of the real-time temperature of each of the first plurality of temperature sensors and each of the second plurality of temperature sensors so as to facilitate evaluation of a property of contact between the compound tip electrode and body tissue.

108. The system of claim 107, wherein the graphical output further comprises a visual representation of an orientation of a distal portion of the ablation catheter relative to the body tissue, wherein the orientation is determined by the at least one processing device based on the data indicative of the temperatures received from the first and second plurality of temperature sensors.

109. The system of claim 107 or 108, wherein the at least one processing device is configured to generate an alert upon determining that the real-time temperature of any of the first plurality of temperature sensors or the second plurality of temperature sensors is above a predetermined threshold temperature.

110. The system of any one of claims 107 to 109, wherein the first plurality of temperature sensors comprises three thermocouples spaced about a longitudinal axis of the ablation catheter, and wherein the second plurality of temperature sensors comprises three thermocouples spaced about the longitudinal axis of the ablation catheter.

111. The system of any one of claims 107 to 110, wherein the graphical output comprises a two-dimensional visual image representing a distal portion of the ablation catheter, and wherein the two-dimensional visual image comprises separate regions for each of the first plurality of temperature sensors and each of the second plurality of temperature sensors.

112. The system of claim 111, wherein the visual representation of the real-time temperature of each of the first plurality of temperature sensors and each of the second plurality of temperature sensors comprises a color corresponding to the real-time temperature of each respective temperature sensor.

113. The system of claim 112, wherein the color changes in color from light to dark as the temperature value increases.

114. The system of claim 112, wherein the first color is associated with a first range of lowest temperature values, wherein the second color is associated with a second range of moderate temperature values, and wherein the third color is associated with a third range of highest temperature values.

115. The system of any of claims 111 to 114, wherein the graphical output further comprises: a first visual representation configured to indicate the real-time temperature of each of the zones corresponding to the first plurality of temperature sensors; and a second visual representation configured to indicate the real-time temperature of each of the zones corresponding to the second plurality of temperature sensors.

116. A graphical user interface system for displaying information to facilitate determining a property of contact between a medical instrument and body tissue during an ablation procedure, the system comprising:

at least one processing device configured to:

receiving data indicative of a temperature of each of a first plurality of temperature sensors located at a distal tip of an ablation catheter;

receiving data indicative of a temperature of each of a second plurality of temperature sensors located a distance proximal to the first plurality of temperature sensors along a length of the ablation catheter;

generating a graphical output indicative of real-time temperatures of each of the first plurality of temperature sensors and each of the second plurality of temperature sensors based on the received data; and is

Generating a graphical output indicative of an orientation of the distal tip of the ablation catheter relative to body tissue; and

a display device operatively coupled to the at least one processing device, wherein the display device is configured to (i) display a graphical output indicative of the real-time temperature of each of the first and second plurality of temperature sensors, and (ii) display a graphical output indicative of the orientation of the distal tip of the ablation catheter relative to body tissue.

117. The system of claim 116, wherein the graphical output indicative of the orientation of the distal tip of the ablation catheter relative to body tissue comprises a two-dimensional image representing the distal tip of the ablation catheter oriented relative to a visual representation of a tissue plane.

118. The system of claim 116 or claim 117, wherein the at least one processing device is configured to generate an alarm upon determining that the real-time temperature of any of the first plurality of temperature sensors or the second plurality of temperature sensors is above a predetermined threshold temperature.

119. The system of any one of claims 116 to 118, wherein the first plurality of temperature sensors comprises three thermocouples spaced about a longitudinal axis of the ablation catheter, and wherein the second plurality of temperature sensors comprises three thermocouples spaced about the longitudinal axis of the ablation catheter.

120. The system of any of claims 116 to 119, wherein the graphical output indicative of the real-time temperature of each of the first and second plurality of temperature sensors comprises separate zones corresponding to each of the first and second plurality of temperature sensors.

121. The system of claim 120 wherein the graphical output includes a color corresponding to the real-time temperature of each respective temperature sensor.

122. The system of claim 121, wherein the color changes in color from light to dark as the temperature value increases.

123. The system of claim 121, wherein the first color is associated with a first range of lowest temperature values, wherein the second color is associated with a second range of intermediate temperature values, and wherein the third color is associated with a third range of highest temperatures.

124. The system of any of claims 120 to 122, wherein the graphical output further comprises: a first visual representation configured to indicate the real-time temperature of each of the zones corresponding to the first plurality of temperature sensors; and a second visual representation configured to indicate the real-time temperature of each of the zones corresponding to the second plurality of temperature sensors.

125. The system of any one of claims 116 to 124, wherein the at least one processing device is configured to store the generated graphical output at one or more time instances during the ablation procedure in a memory operatively coupled to the at least one processing device.

126. The system of any of claims 116 to 125, wherein the at least one processing device is configured to store the real-time temperature values of one or more of the first plurality of temperature sensors and the second plurality of temperature sensors at one or more time instances during the ablation procedure in a memory operatively coupled to the at least one processing device.

127. A method for facilitating assessment of a property of contact between a distal tip of an ablation catheter and body tissue, the method comprising:

determining a temperature value at the location of each of the first plurality of temperature sensors and at the location of each of the second plurality of temperature sensors based on the temperature data;

calculating interpolated temperature values for a plurality of locations along the distal tip of the ablation catheter between at least one of the first plurality of temperature sensors and at least one of the second plurality of temperature sensors;

generating a visual representation of the distal tip of the ablation catheter including graphical information indicative of temperature values at the location of each of the first plurality of temperature sensors and at the location of each of the second plurality of temperature sensors and indicative of the interpolated temperature values,

wherein the graphical information includes a color output, and

wherein the visual representation further indicates a real-time orientation of the distal tip of the ablation catheter relative to the tissue, the real-time orientation determined based on the temperature values determined for the first and second plurality of temperature sensors.

128. The method of claim 127, further comprising: determining a percentage of surface area of the distal tip of the ablation catheter in contact with tissue based on the determined temperature value and the interpolated temperature value.

129. The method of claim 128, wherein determining the percentage of surface area of the distal tip of the ablation catheter in contact with tissue comprises: determining a percentage of a surface area of the distal tip of the ablation catheter that is greater than a predetermined threshold temperature.

130. The method of claim 129, further comprising calculating an index indicative of lesion volume based at least in part on a duration and the determined percentage of surface area of the distal tip of the ablation catheter in contact with tissue.

131. The method of claim 130, further comprising generating an output for display indicating the index.

132. The method of claim 131, wherein the output is a digital output.

133. The method of claim 131, wherein the output is a qualitative output.

134. The method of any one of claims 130 to 133, further comprising: automatically terminating application of radio frequency energy using the ablation catheter when the index is equal to or above a predetermined value.

135. The method of any of claims 130 to 133, further comprising: generating a user alert when the index equals a predetermined value.

136. The method of claim 135, wherein the alarm is one of an audible alarm, a visual alarm, and a tactile alarm.

137. A method that facilitates estimating lesion formation based at least in part on temperature measurements along an electrode of an ablation catheter, the method comprising:

obtaining temperature data from a plurality of temperature sensors positioned along the electrode of the ablation catheter;

determining a temperature value at the location of each of the plurality of temperature sensors based on the temperature data;

calculating interpolated temperature values for a plurality of locations along the electrode between the plurality of temperature sensors;

calculating a percentage of a surface area of the electrode that is equal to or higher than a predetermined temperature indicative of lesion formation based on the determined temperature value and the interpolated temperature value;

calculating an index indicative of lesion volume based at least in part on the duration and the calculated percentage of the surface area of the electrode that is equal to or higher than the predetermined temperature; and

generating an output of the index for display.

138. The method of claim 137, wherein the step of obtaining temperature data from a plurality of temperature sensors positioned along the electrode of the ablation catheter comprises:

obtaining temperature data from at least one temperature sensor located at a proximal end of the electrode;

temperature data is obtained from at least one temperature sensor located at a distal end of the electrode.

139. The method of claim 137, wherein the step of calculating interpolated temperature values for a plurality of locations along the electrode between the plurality of temperature sensors comprises performing bilinear interpolation.

Background

Tissue ablation can be used to treat a variety of clinical conditions. For example, tissue ablation may be used to treat cardiac arrhythmias by at least partially disrupting (e.g., at least partially or completely ablating, interrupting, inhibiting, terminating conduction, otherwise affecting, etc.) abnormal pathways that would otherwise conduct abnormal electrical signals to the heart muscle. Several ablation techniques have been developed, including cryoablation, microwave ablation, Radio Frequency (RF) ablation, and high frequency ultrasound ablation. For cardiac applications, such techniques are typically performed by a clinician introducing a catheter having an ablation tip into the endocardium via the venous vasculature, positioning the ablation tip adjacent to a location deemed appropriate by the clinician to be an area of the endocardium based on tactile feedback, mapping Electrocardiogram (ECG) signals, anatomical structures, and/or fluoroscopic imaging, actuating a flow of irrigation fluid to cool the surface of the selected area, and then actuating the ablation tip for a period of time and at a power deemed sufficient to destroy tissue in the selected area. In ablation procedures involving the delivery of radiofrequency energy using one or more electrodes, clinicians strive to establish a stable and uniform contact between the electrode(s) and the tissue to be ablated.

Successful electrophysiological procedures require accurate knowledge about the anatomical substrate. Additionally, the ablation process may be assessed within a short period of time after completion of the ablation process. Cardiac ablation catheters typically carry only regular mapping electrodes. Cardiac ablation catheters may incorporate high resolution mapping electrodes. Such high-resolution mapping electrodes provide more accurate and detailed information about the anatomical substrate and about the outcome of the ablation process. High-resolution mapping electrodes may allow electrophysiology to accurately assess the morphology of an electrogram, its amplitude and width, and determine changes in pacing thresholds. Morphology, amplitude and pacing thresholds are accepted, and reliable Electrophysiological (EP) markers provide useful information about the outcome of ablation.

Disclosure of Invention

According to some embodiments, a method for facilitating assessment of a property of contact between an electrode assembly of an ablation catheter and living tissue, the method comprising: obtaining a first detected voltage between a first electrode and a second electrode, wherein the first electrode and the second electrode are positioned along an electrode assembly of an ablation catheter, and wherein the first electrode is distal to the second electrode; obtaining a second detection voltage between the second electrode and a third electrode, the third electrode being located proximal to the second electrode; making a first comparison between a first detected voltage and a first threshold voltage, wherein the first threshold voltage is indicative of contact between the living tissue and a first portion of the ablation catheter, the first portion of the ablation catheter being located at a position between the first electrode and the second electrode; and making a second comparison between the second detected voltage and a second threshold voltage, wherein the second threshold voltage is indicative of contact between the living tissue and a second portion of the ablation catheter, the second portion of the ablation catheter being located at a position between the second electrode and the third electrode, wherein contact between the living tissue and the first portion of the ablation catheter is confirmed if the first voltage is equal to or higher than the first threshold voltage, and wherein contact between the living tissue and the second portion of the ablation catheter is confirmed if the second voltage is equal to or higher than the second threshold voltage.

According to some embodiments, the method further comprises displaying a level of contact between the electrode assembly and the living tissue on the graphical representation of the electrode assembly, wherein the first threshold voltage is the same as the second threshold voltage, wherein at least one of the first threshold voltage and the second threshold voltage is equal to or about 0.30mV (e.g., 0.30 v; 0.2-0.4mV, 0.30-0.32, 0.32-0.34, 0.34-0.36, 0.36-0.38, 0.38-0.40, ranges therebetween, etc.), wherein displaying the level of contact between the electrode assembly and the living tissue on the graphical representation of the electrode assembly comprises: comprising a halo or other visual covering surrounding a graphical representation of the electrode assembly, and wherein the halo or other visual covering comprises at least one parameter related to the strength of contact between the electrode assembly and the living tissue.

wherein displaying on the graphical representation of the electrode assembly the level of contact of the electrode assembly with living tissue comprises: comprising a halo or other visual covering surrounding a graphical representation of the electrode assembly, and wherein the halo or other visual covering comprises at least one parameter related to the strength of contact between the electrode assembly and the living tissue. In some embodiments, the first threshold voltage is the same as the second threshold voltage. In some embodiments, the first threshold voltage is within 0-20% of the second threshold voltage (e.g., (0-20, 5-15, 8-12, 5-20, 0-2, 2-4, 4-6, 6-8, 8-10, 10-12, 12-14, 14-16, 16-18, 18-20%, percentages therebetween, etc.).

According to some embodiments, at least one of the first threshold voltage and the second threshold voltage is 0.30 mV. In some embodiments, at least one of the first threshold voltage and the second threshold voltage is between 0.2mV and 0.4mV (e.g., 0.30 v; 0.2-0.4mV, 0.30-0.32, 0.32-0.34, 0.34-0.36, 0.36-0.38, 0.38-0.40, ranges therebetween, etc.).

According to some arrangements, the system includes displaying a level of contact between the electrode assembly and the living tissue on a graphical representation of the electrode assembly. In one arrangement, displaying on the graphical representation of the electrode assembly a level of contact of the electrode assembly with living tissue comprises: including a halo or other visual covering around the graphical representation of the electrode assembly. In some embodiments, the halo or other visual overlay includes at least one parameter related to the strength of contact between the electrode assembly and living tissue. In some configurations, the at least one parameter of the halo or other visual overlay comprises at least one of: size, shape, color, intensity, shading, brightness, contrast, texture, etc.

According to some embodiments, the method further comprises making a determination related to an orientation of the electrode assembly relative to the living tissue. In some embodiments, making a determination regarding the orientation of the electrode assembly relative to the living tissue includes comparing the first comparison to the second comparison. In some arrangements, a determination is made that the electrode assembly is in a parallel orientation with respect to the living tissue when the first detected voltage is equal to or greater than the first threshold voltage, the second detected voltage is equal to or greater than the second threshold voltage, and the first detected voltage and the second detected voltage are within a threshold percentage difference of each other.

According to some embodiments, the threshold percentage difference is 0 to 10% (e.g., 3-7, 2-8, 0-1, 1-2, 2-3, 3-4, 5-6, 6-7, 7-8, 8-9, 9-10%, percentages in between, etc.). In some arrangements, a determination is made that the electrode assembly is in a vertical orientation with respect to the living tissue when the first detected voltage is equal to or above a first threshold voltage and the second detected voltage is below a second threshold voltage.

According to some embodiments, the first electrode comprises a distal tip electrode member and the second electrode is spaced apart from the first electrode by a first gap distance, wherein the first electrode and the second electrode are electrically coupled through the filtering element to form a composite tip electrode assembly. In some arrangements, the first gap distance is 0.5 mm. In some arrangements, the first gap distance is between 0.1mm and 1mm (e.g., 0.1-0.2, 0.2-0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6, 0.6-0.7, 0.7-0.8, 0.8-0.9, 0.9-1mm, ranges therebetween, etc.).

According to some embodiments, the third electrode comprises a ring electrode. In some arrangements, the second electrode is separated from the third electrode by a second gap distance. In one embodiment, the second gap distance is 1 mm. In other arrangements, the second gap distance is between 0.5mm and 2mm (e.g., 1-1.5, 0.5-1, 1.5-2, 1-1.5, 0.5-0.6, 0.6-0.7, 0.7-0.8, 0.8-0.9, 0.9-1, 1-1.1, 1.1-1.2, 1.2-1.3, 1.3-1.4, 1.4-1.5, 1.5-1.6, 1.6-1.7, 1.7-1.8, 1.8-1.9, 1.9-2mm, distances therebetween, and so forth).

According to some embodiments, the method further comprises displaying a real-time temperature of the electrode assembly. In some arrangements, displaying the real-time temperature of the electrode assembly includes a graphical representation. In some arrangements, the graphical representation of the temperature includes a color-coded representation displayed to the user.

According to some embodiments, the method further comprises providing a visual indication to the user of the status of the ablation process. In some arrangements, the determination to provide the visual indication is determined, at least in part, using and (i) at least one of (a) a first comparison between a first detected voltage and a first threshold voltage and (b) a second comparison between a second detected voltage and a second threshold voltage, and (ii) a temperature of the electrode assembly. In one embodiment, providing the visual indication includes displaying a graphical representation on the output indicating a status of the ablation. In some configurations, the graphical representation includes a frame or peripheral border surrounding the graphical representation of the electrode assembly.

According to some embodiments, the frame or peripheral border is configured to change color to inform the user of one or more of: (i) energy delivery to the ablation assembly has not been initiated, (ii) energy delivery to the ablation assembly has been initiated but lesion formation has not begun, (iii) energy delivery to the ablation assembly has been initiated and lesion formation has begun, (iv) energy delivery to the ablation assembly has been initiated and completion of lesion formation is near completion, (v) energy delivery to the ablation assembly has been initiated and completion of lesion formation is completed.

According to some embodiments, the frame or the peripheral border is configured to change color. In some embodiments, the change is a visual configuration of the boundary, which may be configured to notify the user of one or more of: (i) energy delivery to the ablation assembly has not been initiated, (ii) energy delivery to the ablation assembly has been initiated but lesion formation has not begun, (iii) energy delivery to the ablation assembly has been initiated and lesion formation has begun, (iv) energy delivery to the ablation assembly has been initiated and completion of lesion formation is near completion, (v) energy delivery to the ablation assembly has been initiated and completion of lesion formation is completed.

In accordance with some embodiments, a system for ablating tissue and facilitating assessment of a property of contact between an electrode assembly of an ablation catheter and living tissue, the system comprising an ablation catheter, an electrode assembly, and at least one additional electrode, wherein the system is configured to obtain a first detected voltage between a first electrode and a second electrode, wherein the first electrode and the second electrode are positioned along the electrode assembly of the ablation catheter, and wherein the first electrode is distal to the second electrode, wherein the system is configured to obtain a second detected voltage between the second electrode and the at least one additional electrode, the at least one additional electrode being positioned proximal to the second electrode, wherein the system is configured to make a first comparison between the first detected voltage and a first threshold voltage, wherein the first threshold voltage is indicative of contact between the living tissue and a first portion of the ablation catheter, the first portion of the ablation catheter is located at a position between the first electrode and the second electrode, wherein the system is configured to make a second comparison between a second detected voltage and a second threshold voltage, wherein the second threshold voltage is indicative of contact between the living tissue and the second portion of the ablation catheter, the second portion of the ablation catheter is located at a position between the second electrode and the at least one additional electrode, wherein contact between the living tissue and the first portion of the ablation catheter is confirmed if the first voltage is equal to or higher than the first threshold voltage, and contact between the living tissue and the second portion of the ablation catheter is confirmed if the second voltage is equal to or higher than the second threshold voltage.

According to some embodiments, the system further comprises a display configured to display a level of contact between the electrode assembly and the living tissue on the graphical representation of the electrode assembly, wherein the first threshold voltage is the same as the second threshold voltage, wherein at least one of the first threshold voltage and the second threshold voltage is equal to or about 0.30mV (e.g., 0.30 v; 0.2-0.4mV, 0.30-0.32, 0.32-0.34, 0.34-0.36, 0.36-0.38, 0.38-0.40, ranges therebetween, etc.), wherein displaying on the graphical representation of the electrode assembly the level of contact of the electrode assembly with living tissue comprises including a halo or other visual overlay around the graphical representation of the electrode assembly, and wherein the halo or other visual overlay comprises at least one parameter related to the strength of contact between the electrode assembly and living tissue.

According to some embodiments, the system further comprises displaying on the display, the graphical representation of the electrode assembly, a level of contact between the electrode assembly and the living tissue, wherein displaying on the graphical representation of the electrode assembly the level of contact between the electrode assembly and the living tissue comprises: comprising a halo or other visual covering surrounding a graphical representation of the electrode assembly, and wherein the halo or other visual covering comprises at least one parameter related to the strength of contact between the electrode assembly and the living tissue. In some embodiments, the first threshold voltage is the same as the second threshold voltage. In some embodiments, the first threshold voltage is within 0-20% of the second threshold voltage (e.g., (0-20, 5-15, 8-12, 5-20, 0-2, 2-4, 4-6, 6-8, 8-10, 10-12, 12-14, 14-16, 16-18, 18-20%, percentages therebetween, etc.).

According to some arrangements, the system is configured to display a level of contact between the electrode assembly and the living tissue on the graphical representation of the electrode assembly. In one arrangement, displaying on the graphical representation of the electrode assembly a level of contact of the electrode assembly with living tissue comprises: including a halo or other visual covering around the graphical representation of the electrode assembly. In some embodiments, the halo or other visual overlay includes at least one parameter related to the strength of contact between the electrode assembly and living tissue. In some configurations, the at least one parameter of the halo or other visual overlay comprises at least one of: size, shape, color, intensity, shading, brightness, contrast, texture, etc.

According to some embodiments, the system is configured to make a determination related to an orientation of the electrode assembly relative to the living tissue. In some embodiments, making a determination regarding the orientation of the electrode assembly relative to the living tissue includes comparing the first comparison to the second comparison. In some arrangements, a determination is made that the electrode assembly is in a parallel orientation with respect to the living tissue when the first detected voltage is equal to or greater than the first threshold voltage, the second detected voltage is equal to or greater than the second threshold voltage, and the first detected voltage and the second detected voltage are within a threshold percentage difference of each other.

According to some embodiments, the system is configured to display a real-time temperature of the electrode assembly. In some arrangements, displaying the real-time temperature of the electrode assembly includes a graphical representation. In some arrangements, the graphical representation of the temperature includes a color-coded representation displayed to the user.

According to some embodiments, the system is configured to provide a visual indication to the user of the status of the ablation process. In some arrangements, the determination to provide the visual indication is determined, at least in part, using at least one of (i) a first comparison between a first detected voltage and a first threshold voltage and (b) a second comparison between a second detected voltage and a second threshold voltage, and (ii) a temperature of the electrode assembly. In one embodiment, providing the visual indication includes displaying a graphical representation on the output indicating a status of the ablation. In some configurations, the graphical representation includes a frame or peripheral border surrounding the graphical representation of the electrode assembly.

In accordance with some embodiments, the ablation device comprises an elongate body comprising a distal end, an electrode positioned at the distal end of the elongate body, at least one thermal shunt member placing a heat absorbing element in thermal communication with the electrode to selectively remove heat from at least one of the electrode and tissue treated by the electrode when the electrode is activated, wherein the at least one thermal shunt member extends through an interior of the electrode to dissipate and remove heat from the electrode during use, and wherein the at least one thermal shunt member comprises at least one layer or coating such that the at least one thermal shunt member does not extend to an exterior of the elongate body, and at least one fluid conduit extending at least partially through the interior of the elongate body and at least partially through the interior of the at least one thermal shunt member, wherein the at least one thermal shunt member is in thermal communication with at least one fluid conduit configured to place the electrode in fluid communication with a fluid source to selectively remove heat from the electrode or tissue.

According to some embodiments, the at least one thermal shunt member comprises more than 1.5cm²Thermal diffusivity per second, wherein the electrode comprises a composite electrode, wherein the composite electrode comprises a first electrode portion and at least a second electrode portion, wherein an electrically insulating gap is located between the first electrode portion and the at least second electrode portion to facilitate high resolution mapping along a targeted anatomical region, and wherein the at least one fluid conduit comprises at least one opening.

In accordance with some embodiments, an ablation device includes an elongate body (e.g., a catheter, other medical device, etc.) including a distal end, an ablation member located at the distal end of the elongate body, at least one thermal shunt member placing a thermal shunt element in thermal communication with the ablation member to selectively remove heat from at least a portion of the ablation member or tissue treated by the ablation member when the ablation member is activated, wherein the thermal shunt element in the at least one thermal shunt member extends at least partially through an interior of the ablation member to assist in removing and dissipating heat generated by the ablation member during use, at least one layer or coating located at least partially along an outer surface of the at least one thermal shunt member, and at least one fluid conduit extending at least partially through the interior of the elongate body, wherein the at least one thermal shunt member is in thermal communication with the at least one fluid conduit.

According to some embodiments, the at least one layer or coating is electrically insulating, the at least one fluid conduit extending at least partially through the interior of the at least one thermal shunt member; wherein the at least one fluid conduit comprises at least one opening, and wherein the at least one thermal shunt member comprises more than 1.5cm²Thermal diffusivity per second.

According to some embodiments, a method of removing heat from an ablation member during a tissue treatment procedure includes: activating an ablation system, the system comprising an elongate body comprising a distal end, an ablation member located at the distal end of the elongate body, wherein the elongate body of the ablation system comprises at least one thermal shunt member along its distal end, wherein the at least one thermal shunt member extends at least partially through an interior of the ablation member, wherein at least one layer or coating is located at least partially along an outer surface of the at least one thermal shunt member; at least partially removing heat generated by the ablation member along the distal end of the elongate body via at least one thermal shunt member so as to reduce the likelihood of localized hot spots along the distal end of the elongate body, wherein the elongate body further comprises at least one fluid conduit or channel extending at least partially through the interior of the elongate body; and delivering fluid through the at least one fluid conduit or channel to selectively remove heat from the ablation member when the ablation member is activated.

According to some embodiments, at least one layer or coating is electrically insulating. In some embodiments, at least one layer or coating comprises a resistivity of greater than 1000 Ω cm at 20 ℃. In some embodiments, at least one layer or coating is thermally insulating. In some embodiments, at least one layer or coating comprises a thermal conductivity of less than 0.001W/(cm K) at 20 ℃. In some arrangements, at least one layer or coating includes a polymeric material (e.g., a thermoset polymer, polyimide, PEEK, polyester, polyethylene, polyurethane, nylon elastomer (pebax), nylon, hydrated polymer, etc.). In some embodiments, at least one layer or coating comprises a thickness between 1 to 50 μm. In some embodiments, at least one layer or coating comprises a thickness of less than 100 μm. In some arrangements, the at least one layer or coating comprises a single layer or coating. In other embodiments, the at least one layer or coating comprises more than one layer or coating. In some embodiments, at least one layer or coating is positioned directly along a surface of at least one shunt member. In some embodiments, the at least one layer or coating is not positioned directly along a surface of the at least one shunt member. In some embodiments, at least one intermediate member or structure is located between the at least one shunt member and the at least one layer or coating. In some embodiments, the at least one layer or coating is secured to the at least one thermal shunt member using an adhesive. In some embodiments, the at least one layer or coating is secured to the at least one thermal shunt member using a press-fit connection, dip molding (dip molding), or other molding techniques.

According to some embodiments, the at least one thermal shunt member comprises more than 1.5cm²Thermal diffusivity per second. In some embodiments, at least one thermal shunt member comprises diamond (e.g., industrial diamond). In some embodiments, the at least one thermal shunt member comprises graphene or another carbon-based material.

According to some embodiments, the electrode comprises a composite electrode, wherein the composite electrode comprises a first electrode portion and at least a second electrode portion, wherein an electrically insulating gap is located between the first electrode portion and the at least second electrode portion. In some embodiments, the at least one fluid conduit is in direct thermal communication with the at least one thermal shunt member. In some embodiments, the at least one fluid conduit is in indirect thermal communication with the at least one thermal shunt member. In some arrangements, the at least one fluid conduit includes at least one opening, wherein the at least one opening places the flushing fluid passing through the at least one fluid conduit in direct physical contact with at least a portion of the at least one thermal shunt member.

According to some embodiments, a mapping system configured to process data related to a target anatomical location being treated includes at least one processor configured to receive and process the mapping data of the target anatomical location and create a three-dimensional model of the target anatomical location upon execution of specific instructions stored on a computer readable medium, and at least one output device for displaying the three-dimensional model of the target anatomical location to a user, wherein the processor is configured to be operably coupled to at least one component of a separate ablation system, wherein the separate ablation system is configured to selectively ablate at least a portion of the target anatomical location, the separate ablation system including at least one electrode positioned along a distal end of the catheter, the at least one processor configured to receive ablation data from the separate ablation system, wherein the ablation data relates to at least one ablation performed along tissue at the target anatomical location, wherein the mapping system is configured to determine a real-time location of the at least one electrode relative to a three-dimensional model of the target anatomical location to assist a user in ablating tissue at the target anatomical location, and wherein the at least one processor is configured to generate a representation on the at least one output device, the representation including at least a portion of the three-dimensional model of the target anatomical location, the real-time location of the at least one electrode, and ablation data received from a separate ablation system.

According to some embodiments, a mapping system configured to process data related to a target anatomical location being treated comprises at least one processor, wherein the processor is configured to receive and process the mapping data of the target anatomical location and create a three-dimensional model of the target anatomical location upon execution of specific instructions stored on a computer readable medium, wherein the at least one processor is configured to be operably coupled to at least one output device for displaying the three-dimensional model of the target anatomical location to a user, wherein the processor is configured to be operably coupled to at least one component of a separate ablation system, wherein the separate ablation system is configured to selectively ablate at least a portion of the target anatomical location, the separate ablation system comprising at least one electrode positioned along a distal end of the catheter, the at least one processor configured to receive ablation data from the separate ablation system, wherein the ablation data relates to at least one ablation performed along tissue at the target anatomical location, wherein the mapping system is configured to determine a real-time location of the at least one electrode relative to a three-dimensional model of the target anatomical location to assist a user in ablating tissue at the target anatomical location, and wherein the at least one processor is configured to generate a representation on the at least one output device, the representation including at least a portion of the three-dimensional model of the target anatomical location, the real-time location of the at least one electrode, and ablation data received from a separate ablation system.

According to some embodiments, the separate ablation system is integrated with the mapping system into a single system. In some embodiments, the at least one processor of the mapping system is configured to be operably coupled to at least one separate mapping system, wherein the at least one separate mapping system is configured to acquire and process EGM or other electrical activity data of a target anatomical location. In one embodiment, the at least one separate mapping system includes a plurality of mapping electrodes. In some embodiments, the at least one separate mapping system is integrated with the mapping system.

The system of any of the preceding claims, according to some embodiments, wherein the ablation data comprises one or more of: electrode orientation, temperature data related to the tissue being treated, temperature data of one or more sensors included within the system, qualitative or quantitative contact information, impedance information, length or width of a lesion created by the ablation system, volume of a lesion created by the ablation system, heart rate data of the subject, blood pressure data of the subject, and the like.

According to some embodiments, the representation on the at least one output device further includes EGM data, rotor mapping data, and/or other electrical activity data. In some embodiments, EGM data, rotor mapping data, and/or other electrical activity data is received by at least one processor via a separate mapping system operably coupled to the mapping system.

According to some embodiments, the data in the representation on the at least one output device is provided in a textual and/or graphical manner. In some embodiments, at least a portion of the ablation data is displayed along or near the corresponding ablation location on at least one output device.

According to some embodiments, at least a portion of the ablation data is configured to be intermittently displayed on a representation of the at least one output device. In some embodiments, at least a portion of the ablation data is displayed on a representation of the at least one output device when selected by the user. In some embodiments, at least a portion of the ablation data is configured to be displayed on the representation using a selection device for selecting a particular treatment location. In one embodiment, the selection device includes a mouse, a touchpad, a dial (dial), or another type of manipulatable control. In several arrangements, the selection device comprises a touch screen on which a user can make selections using his or her finger.

According to some embodiments, the system further includes an ablation system (e.g., an ablation system that includes a catheter having at least one distal electrode or other energy delivery member, generator, etc.). In some embodiments, the ablation system comprises a radio frequency ablation system.

According to some embodiments, the processor is part of a mapping system. In some embodiments, the processor is not part of the mapping system, but is operably coupled to the mapping system. In some embodiments, the processor is part of a separate ablation system. In one embodiment, the processor is part of a stand-alone interface unit coupled to the mapping system.

According to some embodiments, a method of integrating data from an ablation device with mapping data comprises: generating a three-dimensional map of the target anatomical location using a mapping system; receiving ablation data from an ablation system; and displaying the three-dimensional map and at least a portion of the ablation data on a single output device (e.g., monitor, screen, etc.).

According to some embodiments, the mapping system comprises an electroanatomical navigation system. In some embodiments, the mapping system and the ablation system are integrated into a single system. In other embodiments, the mapping system and the ablation system are separate from each other. In some embodiments, the method additionally includes receiving electrical activity data from a second mapping system. In some embodiments, the electrical activity data includes EGM activity data, rotor mapping data, and/or any other electrical data.

According to some embodiments, the ablation data comprises one or more of: electrode orientation, temperature data related to the tissue being treated, temperature data of one or more sensors included in the system, qualitative or quantitative contact information, impedance information, length or width of a lesion created by the ablation system, volume of a lesion created by the ablation system, heart rate data of the subject, blood pressure data of the subject, and the like.

According to some embodiments, the ablation data is provided in a textual and/or graphical manner on an output device. In some embodiments, at least a portion of the ablation data is displayed along or near the corresponding ablation location on an output device. In some embodiments, at least a portion of the ablation data is configured to be intermittently displayed on an output device.

According to some embodiments, at least a portion of the ablation data is displayed on an output device when selected by a user. In some embodiments, at least a portion of the ablation data is configured to be displayed using a selection device for selecting a particular treatment location. In several arrangements, the selection device includes a mouse, a touch pad, a dial, or another type of manipulatable controller. In some embodiments, the selection device comprises a touch screen, wherein the user can make a selection on the touch screen using his or her finger.

According to some embodiments, the method further comprises alerting the user of potential gaps along the target anatomical location. In one embodiment, alerting the user includes highlighting the gap on the output device.

In accordance with some embodiments, an apparatus for ablation and high resolution of cardiac tissue includes an elongate body (e.g., a catheter, other medical device, etc.) including a distal end and an electrode assembly positioned along the distal end of the elongate body, wherein the electrode assembly includes a first electrode portion, at least a second electrode portion positioned adjacent to the first electrode portion, the first and second electrode portions configured to contact tissue of a subject and deliver radiofrequency energy sufficient to at least partially ablate the tissue, the apparatus further including at least one electrically insulating gap positioned between the first and second electrode portions, the at least one electrically insulating gap including a gap width separating the first and second electrode portions, the apparatus further including at least one separator positioned within the at least one electrically insulating gap, wherein the at least one separator contacts a proximal end of the first electrode portion and a distal end of the second electrode portion. The apparatus additionally includes at least one conductor configured to electrically couple the energy delivery module to at least one of the first electrode portion and the second electrode portion, wherein the at least one conductor is electrically coupled to the energy delivery module, and wherein a frequency of energy provided to the first electrode and the second electrode is in a radio frequency range.

According to some embodiments, the device further comprises a filter element electrically coupling the first electrode portion to the second electrode portion and configured to exhibit a low impedance (e.g., effectively short-circuiting the two electrode portions) at a frequency for delivering ablation energy via the first and second electrode portions, wherein the filter element comprises a capacitor, wherein the capacitor comprises a capacitance of 50 to 300nF (e.g., 100nF, 50-100, 100nF, 150 nF, 200 nF, 250 nF, 300nF, values between the aforementioned ranges, etc.), wherein the elongated body comprises at least one irrigation channel extending to the first electrode portion, wherein the first electrode portion comprises at least one outlet port in fluid communication with the at least one irrigation channel, wherein the gap width is about 0.2 to 1.0mm (e.g., 0.2, 0.2-0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6, 0.6-0.7, 0.7-0.8, 0.8-0.9, 0.9-1.0mm, values between the aforementioned ranges, less than 0.2mm, greater than 1mm, etc.), wherein a series impedance of less than about 3 ohms (Ω) (e.g., 0-1, 1-2, 2-3 ohms, values between the aforementioned ranges, etc.) is introduced across the first and second electrode portions in the operating RF frequency range, and wherein the operating RF frequency range is 200kHz to 10MHz (e.g., 200 + 300, 300 + 400, 400 + 500, 500 + 600, 600 + 700, 700 + 800, 800 + 900, 900 + 1000, up to 10MHz, or higher frequencies between the aforementioned ranges, etc.). Electrode portions or electrode portions may be used interchangeably herein with electrodes.

According to some embodiments, the apparatus further comprises: a first plurality of temperature-measuring devices located within separate bores formed in the distal end of the electrode assembly, the first plurality of temperature-measuring devices (e.g., thermocouples, other temperature sensors, etc.) being thermally insulated from the electrode assembly; and a second plurality of temperature measurement devices (e.g., thermocouples, other temperature sensors, etc.) located within separate apertures positioned relative to the proximal end of the electrode assembly, the second plurality of temperature measurement devices being thermally insulated from the electrode assembly, wherein temperature measurements determined from the first and second plurality of temperature measurement devices facilitate determining an orientation of the electrode assembly relative to the tissue being treated; and at least one thermal shunt member placing the heat absorbing element in thermal communication with the electrode assembly to selectively remove heat from at least one of the electrode assembly and tissue treated by the electrode assembly when the electrode assembly is activated; a contact sensing subsystem comprising a signal source configured to deliver a range of frequencies to the electrode assembly, the contact sensing subsystem further comprising a processing device configured to obtain impedance measurements when the signal source applies different frequencies within the range of frequencies to the electrode assembly, process the impedance measurements obtained at the different frequencies, and determine whether the electrode assembly is in contact with tissue based on the processing of the impedance measurements, wherein the elongate body comprises at least one irrigation channel extending to the first electrode portion.

According to some embodiments, the apparatus further comprises: a first plurality of temperature-measuring devices (e.g., thermocouples, other temperature sensors, etc.) located within separate bores formed in the distal end of the electrode assembly, the first plurality of temperature-measuring devices being thermally insulated from the electrode assembly; and a second plurality of temperature measurement devices (e.g., thermocouples, other temperature sensors, etc.) located within separate apertures positioned relative to the proximal end of the electrode assembly, the second plurality of temperature measurement devices being thermally insulated from the electrode assembly, wherein temperature measurements determined from the first and second plurality of temperature measurement devices facilitate determining an orientation of the electrode assembly relative to the treated tissue.

According to some embodiments, the device further comprises at least one thermal shunt member placing the heat absorbing element in thermal communication with the electrode assembly to selectively remove heat from at least one of the electrode assembly and tissue treated by the electrode assembly when the electrode assembly is activated.

According to some embodiments, the apparatus further comprises a contact sensing subsystem comprising: a signal source configured to deliver a range of frequencies to the electrode assembly; and a processing device configured to obtain impedance measurements when the signal source applies different frequencies within the frequency range to the electrode assembly, process the impedance measurements obtained at the different frequencies, and determine whether the electrode assembly is in contact with tissue based on the processing of the impedance measurements.

According to some embodiments, the filter element comprises a capacitor. In some embodiments, the capacitor comprises a capacitance of 50-300nF (e.g., 100nF, 50-100, 100-150, 150-200, 200-250, 250-300nF, values between the aforementioned ranges, etc.).

According to some embodiments, the at least one thermal shunt member is in thermal communication with at least one fluid conduit (e.g., an internal channel) extending at least partially through the interior of the elongate body, the at least one fluid conduit configured to place the electrode in fluid communication with a fluid source to selectively remove heat from the electrode assembly and/or tissue of the subject located adjacent to the electrode assembly.

According to some embodiments, the second plurality of temperature measurement devices is positioned along a plane substantially perpendicular to the longitudinal axis of the distal end of the elongate body and spaced proximally of the first plurality of temperature measurement devices. In some embodiments, each of the temperature measurement devices includes a thermocouple, a thermistor, and/or any other type of temperature sensor or temperature measurement device or component. In some embodiments, the first plurality of temperature measurement devices comprises at least three (e.g., 3, 4, 5, 6, more than 6, etc.) temperature sensors, and wherein the second plurality of temperature measurement devices comprises at least three (e.g., 3, 4, 5, 6, more than 6, etc.) temperature sensors.

According to some embodiments, the device further comprises at least one conductor configured to electrically couple the energy delivery module to at least one of the first electrode and the second electrode. In some embodiments, the at least one conductor is electrically coupled to the energy delivery module.

According to some embodiments, the frequency of the energy supplied to the first and second electrodes is in the radio frequency range. In some embodiments, the series impedance introduced across the first and second electrodes is lower than: (i) an impedance of a conductor that electrically couples the electrode to the energy delivery module, and (ii) an impedance of the tissue being treated. In some embodiments, the gap width is about 0.2 to 1.0mm (e.g., 0.5mm, 0.2-0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6, 0.6-0.7, 0.7-0.8, 0.8-0.9, 0.9-1.0mm, values between the foregoing ranges, less than 0.2mm, greater than 1mm, etc.). In some embodiments, the elongate body (e.g., catheter) comprises at least one irrigation channel extending to the first electrode.

According to some embodiments, the at least second electrode comprises a second electrode and a third electrode portion, the second electrode portion being axially positioned between the first and third electrode portions, wherein an electrically insulating gap separates the second and third electrode portions. In some embodiments, gaps are included between the first and second electrode portions and between the second and third electrode portions to increase the ratio of mapped tissue surface to ablated tissue surface. In some embodiments, the ratio is between 0.2 and 0.8 (e.g., 0.2-0.3, 0.3-0.4, 0.4-.5, 0.5-0.6, 0.6-0.7, 0.7-0.8, ratios between the foregoing, etc.). In some embodiments, the device further comprises a separator located within the gap between the second and third electrode portions.

According to some embodiments, an apparatus for mapping and ablating tissue includes an elongate body (e.g., a catheter, other medical device, etc.) comprising: a proximal end and a distal end; a first electrode (or electrode portion) on the elongate body; at least a second electrode (or electrode portion) positioned adjacent to the first electrode, the first and second electrodes (or electrode portions) configured to contact tissue of a subject and deliver radiofrequency energy sufficient to at least partially ablate the tissue; the apparatus further comprises at least one electrically insulating gap positioned between the first electrode (or electrode portion) and the second electrode (or electrode portion), the at least one electrically insulating gap comprising a gap width separating the first and second electrodes (or electrode portions); the device also includes a filtering element electrically coupling the first electrode (or electrode portion) to the second electrode (or electrode portion) and configured to exhibit a low impedance (e.g., effectively short-circuiting the two electrodes (electrode portions or electrode portions)) at a frequency for delivering ablation energy via the first and second electrodes (or electrode portions).

According to some embodiments, the apparatus further comprises means for facilitating high resolution mapping. In some embodiments, electrically separating the first and second electrodes (or electrode portions) facilitates high resolution mapping along a targeted anatomical region (e.g., cardiac tissue). In some embodiments, the apparatus further comprises at least one separator positioned within the at least one electrically insulating gap. In one embodiment, the at least one separator contacts a proximal end of the first electrode (or electrode portion or section) and a distal end of the second electrode (or electrode portion or section). In some embodiments, the apparatus further comprises at least one conductor configured to electrically couple the energy delivery module to at least one of the first and second electrodes (or electrode portions). In some embodiments, the at least one conductor is electrically coupled to the energy delivery module.

According to some embodiments, the frequency of the energy provided to the first and second electrodes is in the radio frequency range. In some embodiments, the filter element comprises a capacitor. In some embodiments, the capacitor comprises a capacitance of 50-300nF (e.g., 100nF, 50-100, 100-150, 150-200, 200-250, 250-300nF, values between the foregoing ranges, etc.). In some embodiments, the capacitor comprises a capacitance of 100 nF. In some embodiments, a series impedance of less than about 3 ohms (Ω) (e.g., 0-1, 1-2, 2-3 ohms, values in between the foregoing ranges, etc.) is introduced across the first and second electrodes in the operational RF frequency range. In some embodiments, the operating RF frequency range is 200kHz to 10MHz (e.g., 200-300, 300-400, 400-500, 500-600, 600-700, 700-800, 800-900, 900-1000kHz, up to 10MHz or higher frequencies in between).

According to some embodiments, the series impedance introduced across the first and second electrodes is lower than: (i) an impedance of a conductor that electrically couples the electrode to the energy delivery module, and (ii) an impedance of the tissue being treated. In some embodiments, the gap width is about 0.2 to 1.0mm (e.g., 0.2-0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6, 0.6-0.7, 0.7-0.8, 0.8-0.9, 0.9-1.0mm, values between the foregoing ranges, less than 0.2mm, greater than 1mm, etc.). In some embodiments, the gap width is 0.5 mm.

According to some embodiments, the elongate body comprises at least one irrigation channel extending to the first electrode. In some embodiments, the first electrode (or electrode portion) comprises at least one outlet port in fluid communication with the at least one flush channel.

According to some embodiments, the at least second electrode (or electrode portion or section) comprises a second electrode (or electrode portion or section) and a third electrode (or electrode portion or section), the second electrode (or electrode portion or section) being positioned axially between the first and third electrodes (or electrode portions or sections), wherein an electrically insulating gap separates the second and third electrodes (or electrode portions or sections). In some embodiments, gaps are included between the first and second electrodes (or electrode portions or portions) and between the second and third electrodes (or electrode portions or portions) to increase the ratio of mapped tissue surface to ablated tissue surface. In some embodiments, the ratio is between 0.2 and 0.8 (e.g., 0.2-0.3, 0.3-0.4, 0.4-5, 0.5-0.6, 0.6-0.7, 0.7-0.8, ratios between the foregoing, etc.). In some embodiments, the apparatus further comprises a separator located within the gap between the second and third electrodes (or electrode portions).

According to some embodiments, an ablation device comprises: a first electrode (or electrode portion or section) located at the distal end of the catheter; at least a second electrode (or electrode portion or section) located at a location proximal to the first electrode (or electrode portion or section), the first and second electrodes (or electrode portions or sections) configured to contact tissue of the subject (e.g., cardiac tissue, other targeted anatomical tissue, etc.) and deliver energy sufficient to at least partially ablate the tissue; an electrically insulating gap between the first electrode (or electrode portion) and the second electrode (or electrode portion), the electrically insulating gap comprising a gap width separating the first and second electrodes (or electrode portions); and a filter element electrically coupling the first electrode (or electrode portion or section) to the second electrode (or electrode portion or section).

According to some embodiments, electrically separating the first and second electrodes (or electrode portions) facilitates high resolution mapping along a targeted anatomical region (e.g., cardiac tissue). In some embodiments, the apparatus further comprises at least one separator positioned within the at least one electrically insulating gap. In several embodiments, at least one separator contacts a proximal end of a first electrode (or electrode portion or section) and a distal end of a second electrode (or electrode portion or section).

According to some embodiments, the apparatus additionally comprises at least one conductor configured to excite at least one of the first and second electrodes (or electrode portions). In one embodiment, the at least one conductor is electrically coupled to an energy delivery module (e.g., an RF generator).

According to some embodiments, the device further comprises means for connecting to an electrophysiology recorder. In some embodiments, the device is configured to connect to an electrophysiology recorder.

According to some embodiments, the frequency of the energy provided to the first and second electrodes is in the Radio Frequency (RF) range. In some embodiments, the operating RF frequency range is 200kHz to 10MHz (e.g., 200-300, 300-400, 400-500, 500-600, 600-700, 700-800, 800-900, 900-1000kHz, up to 10MHz or higher frequencies in between). In some embodiments, the filter element comprises a capacitor. In some embodiments, the capacitor comprises a capacitance of 50-300nF (e.g., 100nF, 50-100, 100-150, 150-200, 200-250, 250-300nF, values between the foregoing ranges, etc.). In some embodiments, a series impedance of less than 3 ohms (Ω) (e.g., 0-1, 1-2, 2-3 ohms, values between the foregoing ranges, etc.) is introduced across the first and second electrodes (or electrode portions) at 500 kHz.

According to some embodiments, the at least second electrode (or electrode portion or section) comprises a second electrode (or electrode portion or section) and a third electrode (or electrode portion or section), the second electrode (or electrode portion or section) being positioned axially between the first and third electrodes (or electrode portions or sections), wherein an electrically insulating gap separates the second and third electrodes (or electrode portions or sections). In some embodiments, the separator is located within the gap between the second and third electrodes (or electrode portions). In some embodiments, gaps are included between the first and second electrodes (or electrode portions or portions) and between the second and third electrodes (or electrode portions or portions) to increase the ratio of mapped tissue surface to ablated tissue surface. In some embodiments, the ratio is between 0.2 and 0.8 (e.g., 0.2-0.3, 0.3-0.4, 0.4-5, 0.5-0.6, 0.6-0.7, 0.7-0.8, ratios between the foregoing, etc.).

According to some embodiments, the system further comprises means for connecting to an electrophysiology recorder. In some embodiments, the system is configured to connect to an electrophysiology recorder. In some embodiments, the system includes an ablation device and at least one of (i) a generator for selectively energizing the device and (ii) an electrophysiology recorder.

According to some embodiments, a method of delivering energy to an ablation device comprises: energizing a split-tip or split-portion electrode located on a catheter (or other medical device), the split-tip or split-portion electrode comprising first and second electrodes (or electrode portions) configured to contact tissue of a subject and deliver energy sufficient to at least partially ablate the tissue, wherein an electrically insulating gap is located between the first and second electrodes, the electrically insulating gap comprising a gap width separating the first and second electrodes, wherein a filtering element electrically couples the first electrode to the second electrode, and wherein electrically separating the first and second electrodes facilitates high resolution mapping along a target anatomical region.

According to some embodiments, the method additionally includes receiving high-resolution mapping data from the first and second electrodes (or electrode portions) related to tissue of the subject adjacent the first and second electrodes (or electrode portions). In some embodiments, receiving the high resolution mapping data occurs before, during, or after energizing a split-tip electrode positioned on the catheter.

According to some embodiments, a method of mapping tissue of a subject includes receiving high resolution mapping data using a compound tip electrode (e.g., a split tip or split portion electrode) including first and second electrodes or electrode portions positioned on a catheter and separated by an electrically insulating gap, wherein a filtering element electrically couples the first electrode to the second electrode in an operational RF range, and wherein electrically insulating the first and second electrodes facilitates high resolution mapping along a targeted anatomical region.

According to some embodiments, the method additionally includes energizing at least one of the first electrode and the second electrode to deliver energy sufficient to at least partially ablate tissue of the subject. In some embodiments, the high-resolution mapping data is related to tissue of the subject adjacent to the first and second electrodes. In some embodiments, receiving the high resolution mapping data occurs before, during, or after energizing a split tip electrode or a split electrode positioned on the catheter.

According to some embodiments, the separator is located within the at least one electrically insulating gap. In some embodiments, at least one separator contacts a proximal end of the first electrode and a distal end of the second electrode. In some embodiments, the first electrode and the second electrode are selectively energized using at least one conductor electrically coupled to the energy delivery module. In some embodiments, the mapping data is provided to an electrophysiology recorder.

According to some embodiments, the frequency of the energy provided to the first and second electrodes is in the Radio Frequency (RF) range. In some embodiments, the filter element comprises a capacitor.

In some embodiments, the operating RF frequency range is 200kHz to 10MHz (e.g., 200-300, 300-400, 400-500, 500-600, 400-600, 600-700, 700-800, 800-900, 900-1000kHz, up to 10MHz, or higher frequencies in between). In some embodiments, the filter element comprises a capacitor. In some embodiments, the capacitor comprises a capacitance of 50-300nF (e.g., 100nF, 50-100, 100-150, 150-200, 200-250, 250-300nF, values between the foregoing ranges, etc.). In some embodiments, a series impedance of less than 3 ohms (Ω) (e.g., 0-1, 1-2, 2-3 ohms, values between the foregoing ranges, etc.) is introduced across the first and second electrodes (or electrode portions) at 500 kHz.

According to some embodiments, a kit for ablation and high-resolution mapping of cardiac tissue includes a device for high-resolution mapping, the device further configured to provide ablation energy to a target tissue, the device comprising an elongate body (e.g., a catheter, other medical device, etc.), the elongate body comprising a proximal end and a distal end, the elongate body comprising an electrode assembly, the electrode assembly comprising: first and second high resolution portions, the first high resolution electrode portion being located on the elongate body, the second electrode portion being adjacent to the first electrode portion, the first and second electrode portions being configured to contact tissue of a subject; the device also includes at least one electrically insulating gap located between the first electrode portion and the second electrode portion, the at least one electrically insulating gap including a gap width separating the first and second electrode portions, wherein the first electrode portion is configured to be electrically coupled to the second electrode portion using a filtering element, wherein the filtering element is configured to exhibit a low impedance at frequencies used to deliver ablation energy via the first electrode portion and the second electrode portion, and wherein the device is configured to be positioned within a target tissue of a subject to obtain high resolution mapping data related to the tissue when ablation energy is not delivered to the first and second electrode portions. The kit further comprises: an energy delivery module configured to generate energy for delivery to the electrode assembly; and a processor configured to regulate delivery of energy from the energy delivery module to the electrode assembly.

According to some embodiments, a kit for ablation and high-resolution mapping of cardiac tissue comprises: the ablation system includes an ablation device, an energy delivery module (e.g., a generator) configured to generate energy for delivery to the electrode assembly, and a processor configured to regulate delivery of energy from the energy delivery module to the electrode assembly. In some embodiments, the energy delivery module comprises an RF generator. In some embodiments, the energy delivery module is configured to be coupled to a device.

According to some embodiments, a generator for selectively delivering energy to an ablation device comprises: an energy delivery module configured to generate ablation energy for delivery to an ablation device; and a processor configured to regulate delivery of energy from the energy delivery module to the ablation device.

According to some embodiments, the at least one thermal shunt member is in thermal communication with at least one fluid conduit extending at least partially through the interior of the elongate body, the at least one fluid conduit configured to place the electrode in fluid communication with a fluid source to selectively remove heat from the electrode and/or tissue of the subject located adjacent to the electrode. In some embodiments, the fluid conduit or channel extends at least partially through the interior of the elongate body. In some embodiments, the fluid conduit or passage extends at least partially through the at least one thermal shunt member. In several configurations, the at least one thermal shunt member is at least partially in thermal communication with a thermal convection fluid. In some embodiments, the flow rate of the thermally convective fluid is less than 15ml/min in order to maintain a desired temperature along the electrode during the ablation process. In some embodiments, the flow rate of the thermally convective fluid is less than about 10ml/min in order to maintain a desired temperature along the electrode during the ablation process. In some embodiments, the flow rate of the thermally convective fluid is less than about 5ml/min in order to maintain a desired temperature along the electrode during the ablation process. In some embodiments, the desired temperature along the electrode during the ablation process is 60 degrees celsius. In some embodiments, the thermally convective fluid comprises blood and/or another body fluid.

According to some embodiments, the at least one thermal shunt member comprises more than 1.5cm²Thermal expansion per secondThe scattering rate. In some embodiments, at least one thermal shunt member comprises diamond (e.g., industrial grade diamond). In other embodiments, the at least one thermal shunt member comprises a carbon-based material (e.g., graphene, silicon dioxide, etc.). In some embodiments, the temperature of the at least one thermal shunt member does not exceed 60 to 62 degrees celsius while maintaining a desired temperature along the electrode during the ablation procedure. In some embodiments, the desired temperature along the electrode during the ablation process is 60 degrees celsius.

According to some embodiments, the electrode comprises a Radio Frequency (RF) electrode. In some embodiments, the electrode comprises a composite electrode (e.g., a split tip electrode or a split electrode). In several configurations, a composite electrode includes a first electrode portion and at least a second electrode portion with an electrically insulating gap between the first electrode portion and the at least second electrode portion to facilitate high resolution mapping along a targeted anatomical region.

According to some embodiments, at least a portion of the at least one thermal shunt member extends to the exterior of the catheter adjacent the proximal end of the electrode. In some embodiments, at least a portion of the at least one thermal shunt member extends to the exterior of the catheter adjacent the distal end of the electrode. In some embodiments, at least a portion of the at least one thermal shunt member extends proximally relative to the proximal end of the electrode. In some embodiments, the at least one thermal shunt member comprises a disc or other cylindrical member. In some embodiments, the at least one thermal shunt member comprises at least one extension member extending outwardly from the base member.

According to some embodiments, the at least one fluid conduit comprises at least one fluid delivery conduit and at least one fluid return conduit, wherein the fluid at least partially circulates through the interior of the elongate body via the at least one fluid delivery conduit and the at least one fluid return conduit, wherein the at least one fluid conduit is part of a closed loop or non-open cooling system. In some embodiments, the elongate body comprises a cooling chamber along a distal end of the elongate body, wherein the cooling chamber is configured to be in fluid communication with the at least one fluid conduit. In some embodiments, at least one fluid conduit comprises a metallic material, alloy, and/or the like. In some embodiments, the elongate body does not include a fluid conduit. In some embodiments, the interior of the distal end of the elongate body includes an inner member generally along the position of the electrode. In some embodiments, the inner member comprises at least one thermally conductive material configured to dissipate and/or transfer heat generated by the electrode.

According to several embodiments, the at least one thermal shunt member is in thermal communication with at least one fluid conduit or channel extending at least partially through the interior of the elongate body, the at least one fluid conduit or channel configured to place the ablation member in fluid communication with a fluid source to selectively remove heat from the ablation member and/or tissue of the subject located adjacent to the ablation member. In some embodiments, the at least one thermal shunt member comprises at least one fluid conduit or channel extending at least partially through the interior of the elongate body. In some embodiments, the at least one thermal shunt member does not comprise fluid conduits or channels extending at least partially through the interior of the elongate body. In some embodiments, the interior of the distal end of the elongate body comprises an inner member generally along the location of the ablation member. In several embodiments, the inner member comprises at least one thermally conductive material configured to dissipate and/or transfer heat generated by the ablation member.

According to some embodiments, the ablation member comprises a Radio Frequency (RF) electrode. In some embodiments, the ablation member comprises one of a microwave emitter, an ultrasound transducer, and a cryoablation member.

According to some embodiments, the at least one thermal shunt member comprises more than 1.5cm²Second (e.g., greater than 1.5 cm)²Second or 5cm²Per second (e.g., 1.5-2, 2-2.5, 2.5-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-20 cm)²A value between the aforementioned ranges, greater than 20cm²Per second). In some embodiments, the at least one thermal shunt member comprises more than 5cm²Thermal diffusivity per second. In some embodiments, at least one thermal shunt member comprises diamond (e.g., industrial grade diamond). In some embodiments, the at least one thermal shunt member comprises a carbon-based material (e.g., graphene, silicon dioxide, etc.). In some embodiments, the Radio Frequency (RF) electrode comprises a composite electrode (e.g., a split-tip RF electrode or other high resolution electrode).

According to some embodiments, the at least one fluid conduit or channel is in direct thermal communication with the at least one thermal shunt member. In some embodiments, the at least one flushing conduit is not in direct thermal communication with the at least one thermal shunt member. In some arrangements, the at least one fluid conduit or passage directly contacts the at least one thermal shunt member. In some embodiments, the at least one fluid conduit or channel does not contact the at least one thermal shunt member. In some embodiments, the at least one fluid conduit or channel comprises at least one opening, wherein the at least one opening places the flushing fluid passing through the at least one fluid conduit or channel in direct physical contact with at least a portion of the at least one thermal shunt member. In some embodiments, the at least one opening is positioned along a perforated portion of the at least one conduit or channel, wherein the perforated portion of the at least one conduit or channel is positioned distal to the electrode.

According to some embodiments, at least a portion of the at least one thermal shunt member extends to an exterior of the catheter adjacent the proximal end of the ablation member. In some embodiments, at least a portion of the at least one thermal shunt member extends to an exterior of the catheter adjacent the distal end of the ablation member. In some embodiments, at least a portion of the at least one thermal shunt member extends proximally relative to the proximal end of the ablation member. In some embodiments, the at least one thermal shunt member comprises a disc or other cylindrical member. In several configurations, the at least one thermal shunt member comprises at least one extension member extending outwardly from the base member. In some embodiments, the at least one extension member comprises at least one of a fin, a pin, or a wing. In some embodiments, at least one fluid conduit or channel comprises a metallic material.

According to some embodiments, a method of removing heat from an ablation member during a tissue treatment procedure comprises: activating an ablation system, the system comprising an elongate body (e.g., a catheter, other medical device, etc.) including a distal end, an ablation member located at the distal end of the elongate body, wherein the elongate body of the ablation system includes at least one thermal shunt member along its distal end, wherein the at least one thermal shunt member extends at least partially through an interior of the ablation member; and at least partially removing heat generated by the ablation member along the distal end of the elongate body via the at least one thermal shunt member so as to reduce the likelihood of localized hot spots along the distal end of the elongate body.

According to some embodiments, the elongate body further comprises at least one fluid conduit or channel extending at least partially through an interior of the elongate body, wherein the method further comprises delivering fluid through the at least one fluid conduit or channel, wherein the at least one thermal shunt member places the at least one fluid conduit or channel in thermal communication with the proximal portion of the ablation member to selectively remove heat from the proximal portion of the ablation member when the electrode is activated, wherein the at least one fluid conduit or channel is configured to place the ablation member in fluid communication with a fluid source to selectively remove heat from the ablation member and/or tissue of the subject located adjacent to the ablation member.

According to some embodiments, the at least one fluid conduit or channel is in direct thermal communication with the at least one thermal shunt member. In some embodiments, the at least one flushing conduit is not in direct thermal communication with the at least one thermal shunt member. According to some embodiments, the at least one fluid conduit or channel directly contacts the at least one thermal shunt member. In some embodiments, the at least one fluid conduit or channel does not contact the at least one thermal shunt member. In some embodiments, delivering fluid through the at least one fluid conduit or channel comprises delivering fluid to and through the distal end of the catheter in an open irrigation system. In several configurations, delivering the fluid through the at least one fluid conduit or channel includes circulating the fluid through a distal end of the catheter adjacent the ablation member in a closed fluid cooling system.

According to some embodiments, the elongate body of the ablation system does not include any fluid conduits or channels. In one embodiment, the elongated body comprises an inner member. In some embodiments, the inner member comprises a thermally conductive material in thermal communication with the at least one thermal shunt member to help dissipate and spread heat generated by the ablation member during use. In some embodiments, at least a portion of the at least one thermal shunt member extends to an exterior of the catheter adjacent the proximal end of the ablation member. In some embodiments, at least a portion of the at least one thermal shunt member extends proximally of the proximal end of the ablation member. In some embodiments, at least a portion of the at least one thermal shunt member extends distally of the proximal end of the ablation member such that at least a portion of the at least one thermal shunt member is positioned along the length of the ablation member. In several configurations, the at least one thermal shunt member comprises a disk or other cylindrical member. In some arrangements, the at least one thermal shunt member comprises at least one extension member extending outwardly from the base member. In some embodiments, the at least one extension member comprises at least one of a fin, a pin, a wing, and/or the like.

According to some embodiments, the system includes means for connecting to an electrophysiology recorder. In some embodiments, the system is configured to connect to an electrophysiology recorder. In some embodiments, the system further comprises at least one of (i) a generator for selectively energizing the device and (ii) an electrophysiology recorder. In some embodiments, the system further comprises both (i) a generator for selectively energizing the device and (ii) an electrophysiological recorder.

According to some embodiments, a system for delivering energy to a target tissue of a subject includes a catheter having a high resolution electrode (e.g., a composite electrode, such as a split-tip electrode or a split-section electrode). A composite electrode may comprise two or more electrodes or electrode portions separated by an electrically insulating gap. The filtering element may electrically couple the first and second electrodes or electrode portions, or any adjacent electrode portions (e.g., arranged circumferentially or radially), and may be configured to exhibit a low impedance (e.g., effectively short circuit the two electrodes, electrode portions, or electrode portions) at the frequency used to deliver ablation energy via the first and second electrodes or electrode portions. In some embodiments, electrically separating the first and second electrodes or electrically separating portions of the electrodes (e.g., in a circumferential or radial arrangement) facilitates high resolution mapping along the targeted anatomical region. The catheter may further include a plurality of temperature sensors (e.g., thermocouples) thermally insulated from the electrodes and configured to detect tissue temperature at a depth. The catheter may also include one or more thermal shunt members and/or components for transferring heat away from the electrodes and/or tissue being treated. In some embodiments, such thermal shunt members and/or components include diamond (e.g., industrial diamond) and/or other materials with good thermal diffusion properties. Further, the system may be configured to detect whether and to what extent contact has been achieved between the electrode and the target tissue.

According to some embodiments, an energy delivery device (e.g., an ablation device) includes an elongate body (e.g., a catheter) including proximal and distal ends, a first electrode (e.g., a radio frequency electrode) located at the distal end of the elongate body, and one or more second electrodes (e.g., a radio frequency electrode) located at a location proximal to the first electrode, the first and second electrodes configured to contact tissue of a subject and deliver radio frequency energy sufficient to at least partially ablate the tissue. In alternative embodiments, the electrodes are distributed circumferentially around the catheter or otherwise positioned circumferentially around the catheter (e.g., along four quadrants distributed circumferentially around the catheter shaft separated by spaces). In other embodiments, the catheter may have additional support structures, and multiple electrodes distributed over the support structures may be employed. The apparatus further comprises: at least one electrically insulating gap between the first electrode and the second electrode or portions of the circumferential electrode, the at least one electrically insulating gap comprising a gap width separating the first and second electrodes; and a band-pass filtering element coupling the first electrode to the second electrode or electrically coupling any adjacent electrode portions (e.g., arranged circumferentially or radially) and configured to exhibit a low impedance (e.g., effectively short-circuiting both electrodes or portions) at a frequency for delivering ablation energy via the first and second electrodes. In some embodiments, electrically separating the first and second electrodes or electrically separating portions of the electrodes (e.g., in a circumferential or radial arrangement) facilitates high resolution mapping along the targeted anatomical region. In some embodiments, the ratio of ablated tissue surface to mapped tissue surface is enhanced (e.g., optimized).

The several embodiments disclosed in this application are particularly advantageous because they include one, more or all of the following benefits: the system is configured to deliver energy (e.g., ablation or other types of energy) to the anatomy of the subject and configured for high-resolution mapping; the system is configured to deliver energy to the anatomy of the subject and to detect the effectiveness of the resulting treatment process using its high resolution mapping capabilities and functions; a compound tip design (e.g., a split tip or split design) may be configured to be energized as a unitary tip or portion to more uniformly provide energy to targeted anatomy of a subject and/or the like.

According to some embodiments, the device further comprises a separator located within the at least one electrically insulating gap. In some embodiments, at least one separator contacts a proximal end of the first electrode and a distal end of the second electrode. In some embodiments, the separator at least partially contacts one side of one electrode portion and an opposite side of an adjacent electrode portion. In one embodiment, the first and second electrodes and the separator are cylindrical. In one embodiment, the outer diameters of the electrodes and the separator are equal. In some embodiments, the first and second electrodes comprise quadrants or other portions circumferentially distributed on the catheter shaft. In some embodiments, the first and second electrodes comprise other geometries suitable for distribution on the catheter shaft and also separated by a narrow non-conductive gap. In some embodiments, the apparatus further includes at least one conductor (e.g., wire, cable, etc.) configured to electrically couple an energy delivery module (e.g., RF or other generator) to at least one of the first and second electrodes. In some embodiments, the device further comprises one or more additional conductors connected to each of the first and second electrodes for distributing signals picked up by said electrodes (e.g. cardiac signals) to an Electrophysiological (EP) recorder.

According to some embodiments, the device additionally comprises an electrophysiological recorder. In some embodiments, the frequency of the energy provided to the first and second electrodes is in the operating Radio Frequency (RF) range (e.g., about 300kHz to 10 MHz).

According to some embodiments, the band pass filtering element comprises a capacitor. In some embodiments, the capacitor comprises a capacitance of 50-300nF (e.g., 100nF, 50-100, 100-150, 150-200, 200-250, 250-300nF, values between the foregoing ranges, etc.) depending on, for example, the operating frequency used to deliver the ablation energy. In some embodiments, a series impedance of about 3 ohms (Ω) or less than about 3 ohms (Ω) (e.g., 0-1, 1-2, 2-3 ohms, values in between the foregoing ranges, etc.) is introduced across the first and second electrodes in an operating RF frequency range (e.g., 300kHz to 10 MHz). For example, lower capacitance values (e.g., 5-10nF) may be used at higher frequency ranges (e.g., 10 MHz). In some embodiments, a capacitance value of 100nF may be well suited for applications in the 500kHz frequency range. In some embodiments, the series impedance introduced across the first and second electrodes is lower than: (i) an impedance of a conductor that electrically couples the electrode to the energy delivery module, and (ii) an impedance of the tissue being treated. In some embodiments, the device further comprises a band-pass filtering element electrically coupling the second electrode to the third electrode or to any adjacent electrode portion (e.g., arranged circumferentially or radially) and configured to present a low impedance at a frequency for third ablation energy via the second and third electrodes.

According to some embodiments, the gap width between the first electrode and the second electrode is about 0.2 to 1.0mm (e.g., 0.5 mm). In some embodiments, the elongate body comprises at least one irrigation channel extending to the first electrode. In one embodiment, the first electrode includes at least one outlet port in fluid communication with the at least one irrigation channel.

According to some embodiments, the apparatus further comprises a third electrode, wherein the second electrode is positioned axially between the first and third electrodes, wherein an electrically insulating gap separates the second electrode and the third electrode. In some embodiments, the apparatus further comprises a separator positioned within the gap between the second and third electrodes.

According to some embodiments, the system comprises an ablation device according to any of the embodiments disclosed herein. In some embodiments, the system additionally comprises means for connecting to an electrophysiology recorder. In some embodiments, the system is configured to connect to an electrophysiology recorder. In some embodiments, the system further comprises at least one of (i) a generator for selectively energizing the device and (ii) an electrophysiology recorder.

According to some embodiments, a method of simultaneously delivering energy to an ablation device and mapping tissue of a subject comprises: a composite electrode (e.g., a split tip electrode, a split portion electrode, etc.) separated by a non-conductive gap from a first electrode to a second electrode, the second electrode being located at a position proximal to the first electrode, the first and second electrodes being configured to contact tissue of a subject to deliver energy sufficient to at least partially ablate the tissue and receive high resolution mapping data related to tissue of the subject adjacent the first and second electrodes. In some embodiments, an electrically insulating gap is located between the first electrode and the second electrode, the electrically insulating gap comprising a gap width separating the first electrode and the second electrode. In some embodiments, the filter element electrically couples the first electrode to the second electrode only in the operational RF frequency range. In one embodiment, electrically separating the first and second electrodes facilitates high resolution mapping along the targeted anatomical region.

According to some embodiments, the separator is located within the at least one electrically insulating gap. In one embodiment, at least one separator contacts a proximal end of the first electrode and a distal end of the second electrode.

According to some embodiments, the mapping data is provided to an electrophysiology recorder. In some embodiments, the frequency of the energy provided to the first and second electrodes is in the radio frequency range.

According to some embodiments, the filter element comprises a capacitor. In one embodiment, the capacitor comprises a capacitance of 50 to 300nF (e.g., 100nF), depending on, for example, the operating frequency used for the ablation energy. In some embodiments, a series impedance of about 3 ohms (Ω) is introduced across the first and second electrodes at 500 kHz. In some embodiments, the series impedance introduced across the first and second electrodes is lower than: (i) an impedance of a conductor that electrically couples the electrode to the energy delivery module, and (ii) an impedance of the tissue being treated.

According to some embodiments, the gap width is about 0.2 to 1.0 mm. In one embodiment, the gap width is 0.5 mm.

In accordance with some embodiments, an ablation device includes an elongate body (e.g., a catheter, other medical instrument, etc.) including a distal end, an electrode at the distal end of the elongate body, and at least one thermal shunt member placing a heat absorbing element in thermal communication with the electrode to selectively remove heat from at least one of the electrode and tissue treated by the electrode when the electrode is activated, wherein the at least one thermal shunt member extends at least partially through an interior of the electrode to dissipate and remove heat from the electrode during use. In some embodiments, the at least one thermal shunt member is in thermal communication with at least one fluid conduit extending at least partially through the interior of the elongate body, the at least one fluid conduit configured to place the electrode in fluid communication with a fluid source to selectively remove heat from the electrode and/or tissue of the subject adjacent the electrode. In some embodiments, the fluid conduit or channel extends at least partially through the interior of the elongate body. In one embodiment, the fluid conduit or passage extends at least partially through the at least one thermal shunt member. In some embodiments, the at least one thermal shunt member is at least partially in thermal communication with the thermal convection fluid. In some embodiments, the thermally convective fluid comprises blood and/or another body fluid.

According to some embodiments, the flow rate of the thermally convective fluid is less than 15ml/min in order to maintain a desired temperature along the electrode during the ablation process. In some embodiments, the flow rate of the thermally convective fluid is less than about 10ml/min in order to maintain a desired temperature along the electrode during the ablation process. In some embodiments, the flow rate of the thermally convective fluid is less than about 5ml/min in order to maintain a desired temperature along the electrode during the ablation process. According to some embodiments, the desired temperature along the electrode during the ablation process is 60 degrees celsius.

According to some embodiments, the at least one thermal shunt member comprises more than 1.5cm²Second or 5cm²Per second (e.g., 1.5-2, 2-2.5, 2.5-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-20 cm)²A value between the aforementioned ranges, greater than 20cm²Per second). In some embodiments, at least one thermal shunt member comprises diamond (e.g., industrial grade diamond). In some embodiments, the at least one thermal shunt member comprises a carbon-based material. In some embodiments, the at least one thermal shunt member comprises at least one of graphene and silicon dioxide.

According to some embodiments, the temperature of the at least one thermal shunt member does not exceed 60 to 62 degrees celsius while maintaining a desired temperature along the electrode during the ablation procedure. In some embodiments, the desired temperature along the electrode during the ablation process is 60 degrees celsius.

According to some embodiments, the electrode comprises a Radio Frequency (RF) electrode. In some embodiments, the electrode comprises a composite electrode (e.g., a split tip electrode). In some embodiments, a composite electrode includes a first electrode portion and at least a second electrode portion, with an electrically insulating gap between the first electrode portion and the at least second electrode portion to facilitate high resolution mapping along a targeted anatomical region.

According to some embodiments, the at least one fluid conduit is in direct thermal communication with the at least one thermal shunt member. In some embodiments, the at least one fluid conduit is not in direct thermal communication with the at least one thermal shunt member. In some embodiments, the at least one fluid conduit comprises at least one opening, wherein the at least one opening places the flushing fluid passing through the at least one fluid conduit in direct physical contact with at least a portion of the at least one thermal shunt member. In some embodiments, the at least one opening is positioned along a perforated portion of the at least one conduit, wherein the perforated portion of the at least one conduit is positioned distal to the electrode. In one embodiment, the at least one fluid conduit is in fluid communication only with an exit port located along the distal end of the elongate body. In some embodiments, the at least one fluid conduit directly contacts the at least one thermal shunt member. In some embodiments, the at least one fluid conduit does not contact the at least one thermal shunt member. In some embodiments, at least a portion of the at least one thermal shunt member extends to the exterior of the catheter adjacent the proximal end of the electrode. In one embodiment, at least a portion of the at least one thermal shunt member extends to the exterior of the catheter adjacent the distal end of the electrode. In certain embodiments, at least a portion of the at least one thermal shunt member extends proximally relative to the proximal end of the electrode. In some embodiments, the at least one thermal shunt member comprises a disc or other cylindrical member.

In accordance with some embodiments, an ablation apparatus includes an elongate body (e.g., a catheter, other medical device, etc.) including a distal end, an ablation member located at the distal end of the elongate body, and at least one thermal shunt member placing a thermal shunt element in thermal communication with an electrode to selectively remove heat from at least one of the electrode and tissue treated by the electrode when the electrode is activated, wherein the thermal shunt element of the at least one thermal shunt member extends at least partially through an interior of the ablation member to assist in removing and dissipating heat generated by the ablation member during use. In some embodiments, the at least one thermal shunt member is in thermal communication with at least one fluid conduit or channel extending at least partially through the interior of the elongate body, the at least one fluid conduit or channel configured to place the ablation member in fluid communication with a fluid source to selectively remove heat from the ablation member and/or tissue of the subject located adjacent to the ablation member.

According to some embodiments, the at least one thermal shunt member comprises at least one fluid conduit or channel extending at least partially through the interior of the elongate body. In some embodiments, the at least one thermal shunt member does not comprise fluid conduits or channels extending at least partially through the interior of the elongate body. In some embodiments, the interior of the distal end of the elongate body comprises an inner member generally along the location of the ablation member. In one embodiment, the inner member comprises at least one thermally conductive material configured to dissipate and/or transfer heat generated by the ablation member.

According to some embodiments, the at least one thermal shunt member comprises at least one extension member extending outwardly from the base member. In some embodiments, the at least one fluid conduit comprises at least one fluid delivery conduit and at least one fluid return conduit, wherein the fluid at least partially circulates through the interior of the elongate body via the at least one fluid delivery conduit and the at least one fluid return conduit, wherein the at least one fluid conduit is part of a closed loop or non-open cooling system. In some embodiments, the elongate body comprises a cooling chamber along a distal end of the elongate body, wherein the cooling chamber is configured to be in fluid communication with the at least one fluid conduit. In some embodiments, the at least one fluid conduit comprises at least one of a metallic material and an alloy. In some embodiments, the elongate body does not include a fluid conduit. In one embodiment, the interior of the distal end of the elongate body includes an inner member generally along the position of the electrode. In some embodiments, the inner member comprises at least one thermally conductive material configured to dissipate and/or transfer heat generated by the electrode.

According to some embodiments, a method of removing heat from an ablation member during a tissue treatment procedure comprises: activating an ablation system, the system comprising an elongate body comprising a distal end, an ablation member at the distal end of the elongate body, wherein the elongate body of the ablation system comprises at least one thermal shunt member along its distal end, wherein the at least one thermal shunt member extends at least partially through an interior of the ablation member; and at least partially removing heat generated by the ablation member along the distal end of the elongate body via the at least one thermal shunt member so as to reduce the likelihood of localized hot spots along the distal end of the elongate body.

According to some embodiments, the elongate body (e.g., catheter, medical device, etc.) further comprises at least one fluid conduit or channel extending at least partially through an interior of the elongate body, the method further comprising delivering fluid through the at least one fluid conduit or channel, wherein the at least one thermal shunt member places the at least one fluid conduit or channel in thermal communication with the proximal portion of the ablation member to selectively remove heat from the proximal portion of the ablation member when the electrode is activated, wherein the at least one fluid conduit or channel is configured to place the ablation member in fluid communication with a fluid source to selectively remove heat from the ablation member and/or tissue of the subject located adjacent to the ablation member.

According to some embodiments, the elongated body is advanced through a body lumen of the subject to a target anatomical location of the subject. In some embodiments, the body lumen of the subject comprises a blood vessel, an airway, or another lumen of the respiratory tract, a lumen of the digestive tract, a urinary lumen, or another body lumen. In some embodiments, the ablation member comprises a Radio Frequency (RF) electrode. In some embodiments, the ablation member comprises one of a microwave emitter, an ultrasound transducer, and a cryoablation member. In some embodiments, the at least one thermal shunt member comprises greater than 1.5cm²Second or 5cm²Per second (e.g., 1.5-2, 2-2.5, 2.5-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-20 cm)²A value between the aforementioned ranges, greater than 20cm²Per second). In some embodiments, at least one thermal shunt member comprises diamond (e.g., industrial grade diamond). In some embodiments, the at least one thermal shunt member comprises a carbon-based material. In some embodiments, the at least one thermal shunt member is comprised of graphene and silicaAt least one of (1).

According to some embodiments, a Radio Frequency (RF) electrode includes a composite RF electrode (e.g., a split-tip RF electrode). In some embodiments, the method further comprises obtaining at least one high resolution image of a target anatomical location of the subject adjacent to the ablation member. In some embodiments, at least one fluid conduit or channel is in direct thermal communication with at least one thermal shunt member. In some embodiments, the at least one flushing conduit is not in direct thermal communication with the at least one thermal shunt member. In some embodiments, the at least one fluid conduit or channel directly contacts the at least one thermal shunt member. In one embodiment, the at least one fluid conduit or channel does not contact the at least one thermal shunt member. In certain embodiments, delivering fluid through the at least one fluid conduit or channel comprises delivering fluid to and through the distal end of the catheter in an open irrigation system. In some embodiments, delivering the fluid through the at least one fluid conduit or channel comprises circulating the fluid through a distal end of the catheter adjacent the ablation member in a closed fluid cooling system.

According to some embodiments, the elongate body (e.g., catheter, medical device) of the ablation system does not include any fluid conduits or channels. In some embodiments, the distal end of the elongate body comprises an inner member. In some embodiments, the inner member comprises a thermally conductive material in thermal communication with the at least one thermal shunt member to help dissipate and spread heat generated by the ablation member during use. In some embodiments, at least a portion of the at least one thermal shunt member extends to an exterior of the catheter adjacent the proximal end of the ablation member. In one embodiment, at least a portion of the at least one thermal shunt member extends proximally of the proximal end of the ablation member. In some embodiments, at least a portion of the at least one thermal shunt member extends distally of the proximal end of the ablation member such that at least a portion of the at least one thermal shunt member is positioned along the length of the ablation member. In some embodiments, the at least one thermal shunt member comprises a disc or other cylindrical member. In one embodiment, the at least one thermal shunt member comprises at least one extension member extending outwardly from the base member. In some embodiments, the at least one extension member comprises at least one of a fin, a pin, or a wing.

According to some embodiments, a system comprising a device according to the present application further comprises means for connecting to an electrophysiological recorder. In some embodiments, the system is configured to connect to an electrophysiology recorder. In some embodiments, the system further comprises at least one of (i) a generator for selectively energizing the device and (ii) an electrophysiology recorder.

According to some embodiments, an ablation device includes an elongate body (e.g., a catheter) having a distal end, an electrode (e.g., an RF electrode, a composite electrode, etc.) at least at the distal end of the elongate body, at least one irrigation conduit extending at least partially through the interior of the elongate body configured to place the electrode in fluid communication with a fluid source to selectively remove heat from the electrode and/or tissue of a subject located adjacent the electrode, and at least one heat transfer member placing the at least one irrigation conduit in thermal communication with a proximal portion of the electrode to selectively remove heat from a proximal portion of the electrode when the electrode is activated.

According to some embodiments, an ablation device includes an elongate body (e.g., a catheter, other medical device, etc.) including a distal end, an ablation member located at the distal end of the elongate body, at least one irrigation conduit extending at least partially through an interior of the elongate body, the at least one irrigation conduit configured to place the ablation member in fluid communication with a fluid source, and at least one heat transfer member placing the at least one irrigation conduit in thermal communication with a proximal portion of the ablation member to selectively remove heat from the proximal portion of the ablation member when the electrodes are activated. In some embodiments, the ablation member comprises a Radio Frequency (RF) electrode, a microwave emitter, an ultrasound transducer, a cryoablation member, and/or any other member.

According to some embodiments, the at least one heat transfer member comprises a thermal conductivity greater than 300W/m/deg.C (e.g., 300-. In other embodiments, at least one heat transfer member comprises a thermal conductivity greater than 500W/m/deg.C (e.g., 500-550, 550-600, 600-650, 650-700, 700-800, 800-900, 900-1000W/m/deg.C, ranges therebetween, greater than 1000W/m/deg.C, etc.).

According to some embodiments, the at least one heat transfer member comprises diamond (e.g., industrial grade diamond). In some embodiments, the at least one heat transfer member comprises at least one of a metal and an alloy (e.g., copper, beryllium, brass, etc.).

According to some embodiments, the electrode comprises a Radio Frequency (RF) electrode. In one embodiment, the electrode comprises a compound electrode (e.g., a split tip electrode). In some embodiments, a composite electrode includes a first electrode portion and at least a second electrode portion, with an electrically insulating gap between the first electrode portion and the at least second electrode portion to facilitate high resolution mapping along a targeted anatomical region.

According to some embodiments, the apparatus further comprises a radiometer. In some embodiments, the radiometer is located in the catheter (e.g., at or near the electrodes or other ablation members). However, in other embodiments, the radiometer is located in the handle of the device and/or at another location of the device and/or companion system. In an embodiment of the apparatus that includes a radiometer, the catheter includes one or more antennas (e.g., at or near the electrodes) configured to detect microwave signals emitted by the tissue. In some embodiments, the device does not include a radiometer or does not include radiometric techniques (e.g., for measuring the temperature of tissue). As discussed herein, other types of temperature measurement devices (e.g., thermocouples, thermistors, other temperature sensors, etc.) may be incorporated into a device or system.

According to some embodiments, the ablation device consists essentially of: the ablation system includes a catheter, an ablation member (e.g., RF electrode, composite electrode, etc.), an irrigation conduit extending through an interior of the catheter to or near the ablation member, at least one electrical conductor (e.g., wire, cable, etc.) for selectively activating the ablation member, and at least one heat transfer member that places at least a portion of the ablation member (e.g., a proximal portion of the ablation member) in thermal communication with the irrigation conduit.

According to some embodiments, the ablation device consists essentially of: the ablation system includes a catheter, an ablation member (e.g., RF electrode, composite electrode, etc.), an irrigation conduit extending through an interior of the catheter to or near the ablation member, at least one electrical conductor (e.g., wire, cable, etc.) for selectively activating the ablation member, an antenna configured to receive microwave signals emitted by tissue of a subject, a radiometer, and at least one heat transfer member that places at least a portion of the ablation member (e.g., a proximal portion of the ablation member) in thermal communication with the irrigation conduit.

According to some embodiments, the at least one flushing conduit is in direct thermal communication with the at least one heat transfer member. In some embodiments, the at least one flushing conduit is not in direct thermal communication with the at least one heat transfer member. In some embodiments, the irrigation catheter is in fluid communication only with an exit port located along the distal end of the elongate body. In some embodiments, the catheter includes only irrigation exit openings along the distal end of the catheter (e.g., along the distal end or the electrodes). In some embodiments, the system does not include any flushing openings along the heat transfer member.

According to some embodiments, the at least one flushing pipe directly contacts the at least one heat transfer member. In some embodiments, the at least one flushing conduit does not contact the at least one heat transfer member. In one embodiment, at least a portion of the heat transfer member extends outside of the catheter adjacent the proximal end of the electrode. In some embodiments, at least a portion of the heat transfer member extends proximally of the proximal end of the electrode. In certain embodiments, at least a portion of the heat transfer member extends distally of the proximal end of the electrode such that at least a portion of the heat transfer member is positioned along the length of the electrode. According to some embodiments, the at least one flushing pipe comprises a metallic material and/or other heat conducting material.

According to some embodiments, the heat transfer member comprises a disc or other cylindrical member. In some embodiments, the heat transfer member includes at least one extension member extending outwardly from the base member.

According to some embodiments, the device further comprises a radiometer to enable the device and/or companion system to detect the temperature of tissue at a depth of the subject. In some embodiments, the radiometer is at least partially included in the catheter. In other embodiments, the radiometer is located at least partially in the handle of the system and/or in a portion of the companion system external to the device and/or catheter.

In accordance with some embodiments, a method of removing heat from an ablation member during an ablation procedure includes activating an ablation system and delivering fluid through at least one irrigation conduit, wherein the system comprises an elongate body comprising a distal end, an ablation member at the distal end of the elongate body, at least one irrigation conduit extending at least partially through the interior of the elongate body, and at least one heat transfer member, wherein the at least one irrigation conduit is configured to place the ablation member in fluid communication with a fluid source, to selectively remove heat from the ablation member and/or tissue of the subject located adjacent to the ablation member, the at least one heat transfer member places the at least one irrigation conduit in thermal communication with the proximal portion of the ablation member to selectively remove heat from the proximal component of the ablation member when the electrode is activated.

According to some embodiments, the ablation member comprises a Radio Frequency (RF) electrode, a microwave emitter, an ultrasound transducer, a cryoablation member, and/or the like. In some embodiments, the at least one heat transfer member comprises a thermal conductivity greater than 300W/m/° C. In one embodiment, the at least one heat transfer member comprises a thermal conductivity greater than 500W/m/° C.

According to one embodiment, a medical device (e.g., an ablation catheter) includes an elongate body having a proximal end and a distal end. The medical device also includes an energy delivery member at the distal end of the elongate body configured to deliver energy to a target tissue. The medical device further comprises: a first plurality of temperature measurement devices located within and thermally insulated from the energy delivery member; and a second plurality of temperature-measurement devices positioned along the elongate body and axially spaced apart from the first plurality of temperature-measurement devices, the second plurality of temperature-measurement devices also being thermally insulated from the energy delivery member. The energy delivery member may optionally be configured to contact tissue. The first plurality of temperature measurement devices may optionally be positioned along a first plane substantially perpendicular to the longitudinal axis of the elongate body. The second plurality of temperature measurement devices may optionally be positioned along a second plane substantially perpendicular to the longitudinal axis of the elongate body and axially spaced apart along the longitudinal axis proximal to the first plane. The energy delivery member may optionally comprise one or more electrode portions, one or more ultrasound transducers, one or more laser elements, or one or more microwave emitters.

According to one embodiment, a medical device (e.g., an ablation catheter or other apparatus) includes an elongate body having a proximal end and a distal end. The medical device includes at least one energy delivery member (e.g., a tip electrode or a plurality of electrode portions) located at a distal end of the elongate body. In this embodiment, the at least one energy delivery member is configured to deliver energy (e.g., radiofrequency energy, acoustic energy, microwave energy, laser energy) to the target tissue with or without contact with the tissue. In one embodiment, the energy is sufficient to generate a lesion at a depth from the surface of the target tissue. Embodiments of the medical instrument include a first plurality of temperature-measuring devices carried by or positioned within separate holes, recesses, or other openings formed in a distal end (e.g., distal-most surface) of the at least one energy delivery member. The first plurality of temperature measurement devices are thermally insulated from the energy delivery member. Embodiments of the medical instrument include a second plurality of temperature-measurement devices positioned adjacent (e.g., within 1mm of) a proximal end of at least one energy delivery member (e.g., carried by or within the energy delivery member, or carried by or within an elongate body proximal to the proximal end of the energy delivery member), the second plurality of temperature-measurement devices being thermally insulated from the at least one energy delivery member. The second plurality of temperature measurement devices may be positioned just proximal or just distal to the proximal end of the at least one energy delivery member. If the medical instrument includes two or more energy delivery members, the second plurality of temperature measurement devices may be positioned adjacent to the proximal edge of the most proximal energy delivery member, and the first plurality of temperature measurement devices may be positioned within the most distal energy delivery member. In some embodiments, the second plurality of temperature measurement devices are positioned proximally of the at least one energy delivery member along the thermal shunt member (e.g., heat transfer member). In some embodiments, the second plurality of temperature-measurement devices is positioned along a plane perpendicular or substantially perpendicular to the longitudinal axis of the distal end of the elongate body and spaced proximally of the first plurality of temperature-measurement devices.

In some embodiments, each temperature measurement device includes a thermocouple or thermistor (e.g., a type K or type T thermocouple). In some embodiments, the first plurality of temperature measurement devices comprises at least three temperature measurement devices and the second plurality of temperature measurement devices comprises at least three temperature measurement devices. In one embodiment, the first plurality of temperature measurement devices consists of only three temperature measurement devices, and the second plurality of temperature measurement devices consists of only three temperature measurement devices. Each of the first plurality of temperature measurement devices and each of the second plurality of temperature measurement devices may be spaced apart (equally or unequally spaced) from each of its respective group of other temperature measurement devices (e.g., circumferentially or radially around the outer surface of the elongate body or otherwise arranged). For example, where three temperature measurement devices are included in each of the plurality of temperature measurement devices, each group of temperature measurement devices, or each group of temperature measurement devices, the temperature measurement devices may be spaced approximately 120 degrees apart. In some embodiments, the first and second pluralities of temperature-measurement devices protrude or otherwise extend beyond an outer surface of the elongate body to facilitate insertion (e.g., embedding) to an increased depth within the target tissue. In one embodiment, the elongate body is cylindrical or substantially cylindrical. The distal end of the temperature measurement device may include a generally circular housing or casing to reduce the likelihood of penetrating or scraping the target tissue.

According to one embodiment, a medical device (e.g., an ablation apparatus) includes an elongate body having a proximal end and a distal end, and a combination or high resolution electrode assembly (e.g., a composite electrode assembly, such as a split-tip electrode assembly) located at the distal end of the elongate body. A composite electrode assembly or other high resolution electrode assembly includes: a first electrode member at a distal tip of the distal end of the elongate body; a second electrode member located proximal to and spaced apart from the first electrode member; and an electrically insulating gap between the first and second electrode members. The first and second electrode members may be configured to contact tissue of a subject and deliver radiofrequency energy to the tissue. In some embodiments, the energy may be sufficient to ablate tissue. The electrically insulating gap may comprise a gap width separating the first electrode member and the second electrode member. An embodiment of a medical device comprises: a first plurality of temperature sensors positioned within separate openings, holes, slits, slots, grooves, or bores formed in the first electrode member and spaced apart (e.g., circumferentially, radially, or otherwise); and a second plurality of temperature sensors positioned at a region proximal of the second electrode member (e.g., adjacent to a proximal edge of the second electrode member (within less than 1mm from the proximal edge of the second electrode member, just proximal or just distal to the proximal edge of the second electrode member)). Positioning within 1mm of the proximal edge may advantageously provide a more useful or important temperature measurement, since the typically hottest spot is formed at the proximal edge of the electrode. The second plurality of temperature sensors is thermally insulated from the second electrode member. In some embodiments, the second plurality of temperature sensors are circumferentially or radially spaced about the outer peripheral surface of the elongate body. The first plurality of temperature sensors may be thermally insulated from the first electrode member and may extend beyond an outer surface (e.g., a distal-most surface) of the first electrode member. In one embodiment, at least a portion of each of the second plurality of temperature sensors extends beyond the outer peripheral surface of the elongated body.

In some embodiments, the medical device includes a heat exchange chamber (e.g., a flush tube) extending at least partially through the interior of the elongate body. The medical instrument may be coupled to a fluid source configured to supply cooling fluid to the heat exchange chamber and a pump configured to control delivery of cooling fluid from the fluid source to the heat exchange chamber through one or more lumens within the heat exchange chamber. In one embodiment, the first electrode member includes a plurality of irrigation exit ports in fluid communication with the heat exchange chamber such that cooling fluid supplied by the fluid source exits from the irrigation exit ports to provide cooling to the composite electrode assembly or other high resolution electrode assembly, blood, and/or tissue being treated.

For an open irrigation arrangement, a medical instrument (e.g., an ablation device) may include a fluid delivery lumen having a smaller diameter or other cross-sectional dimension than the lumen of the heat exchange chamber (e.g., irrigation tubing) to facilitate increased velocity for discharging saline or other fluid out of the irrigation exit port at a regular flow rate. For a closed flushing arrangement, the medical device may comprise: an inlet lumen (e.g., a fluid delivery lumen) extending between the heat exchange chamber and the fluid source, and an outlet lumen (e.g., a return lumen) extending between the heat exchange chamber (e.g., a flush tube) and a return reservoir external to the medical instrument. In one embodiment, the distal end (e.g., outlet) of the inlet chamber is distally spaced from the distal end (e.g., inlet) of the outlet chamber to induce turbulence or other circulation within the heat exchange chamber. In various embodiments, the flush flow rate is 10mL/min or less (e.g., 9mL/min or less, 8mL/min or less, 7mL/min or less, 6mL/min or less, 5mL/min or less). In some embodiments, the medical device is not flushed.

According to one embodiment, a medical device (e.g., an ablation apparatus) includes an elongate body (e.g., a catheter, a wire, a stylet, etc.) including a proximal end and a distal end and a longitudinal axis extending from the proximal end to the distal end. The medical device includes a combination or high resolution electrode assembly (e.g., a composite electrode assembly, such as a split-tip electrode assembly). In this embodiment, the composite electrode assembly includes: a first electrode member at a distal tip of the distal end of the elongate body, and a second electrode member proximal to and spaced apart from the first electrode member. The first and second electrode members are configured to contact tissue of a subject and deliver radiofrequency energy to the tissue. The delivered energy may be sufficient to at least partially ablate or otherwise heat the tissue. The composite electrode assembly also includes an electrically insulating gap including a gap width separating the first electrode member and the second electrode member. Embodiments of the ablation device further comprise: at least one heat transfer member in thermal communication with the first and second electrode members to selectively remove or dissipate heat from the first and second electrode members; a first plurality of temperature measurement devices located within and spaced apart (e.g., circumferentially, axially) from the first electrode member; a second plurality of temperature measurement devices located within a portion of the at least one thermal shunt member (e.g., heat transfer member) proximal to the second electrode member. The first plurality of temperature measurement devices is thermally insulated from the first electrode member and may extend beyond an outer surface of the first electrode member in a direction at least substantially parallel to the longitudinal axis of the elongate body. The second plurality of thermocouples is thermally insulated from the second electrode member and may extend beyond an outer surface of the at least one thermal shunt member in a direction at least substantially perpendicular to the longitudinal axis of the elongate body.

In some embodiments, the medical device includes a heat exchange chamber (e.g., a flush tube) extending at least partially through the interior of the elongate body. The medical instrument may be fluidly coupled to a fluid source configured to supply cooling fluid to the heat exchange chamber and a pump configured to control delivery of the cooling fluid. In one embodiment, the first electrode member includes a plurality of flush exit ports in fluid communication with the heat exchange chamber such that cooling fluid supplied by a fluid source is discharged from the flush exit ports to provide cooling to the composite electrode assembly (e.g., a split electrode assembly). In some embodiments, at least the inner surface or layer of the heat exchange chamber comprises a biocompatible material, such as stainless steel.

In some embodiments, the at least one thermal shunt member (e.g., thermal shunt network or heat transfer member (s)) comprises a thermal conductivity greater than 300W/m/deg.C (e.g., 300-. In other embodiments, at least one heat transfer member comprises a thermal conductivity greater than 500W/m/deg.C (e.g., 500-550, 550-600, 600-650, 650-700, 700-800, 800-900, 900-1000W/m/deg.C, ranges therebetween, greater than 1000W/m/deg.C, etc.). According to some embodiments, the at least one heat transfer member comprises diamond (e.g., industrial grade diamond).

In any of the embodiments, the electrode member(s) may comprise platinum. The temperature measuring device may comprise one or more of the following types of thermocouples: nickel alloys, platinum/rhodium alloys, tungsten/rhenium alloys, gold/iron alloys, noble metal alloys, platinum/molybdenum alloys, iridium/rhodium alloys, pure noble metals, K-type, T-type, E-type, J-type, M-type, N-type, B-type, R-type, S-type, C-type, D-type, G-type, and/or P-type.

According to some embodiments, the medical device comprises at least one separator located within the at least one electrically insulating gap. In one embodiment, the at least one divider comprises a portion of the at least one heat transfer member. For example, the at least one separator may comprise industrial grade diamond.

According to some embodiments, a medical device includes at least one conductor configured to conduct electrical current from an energy source to a composite electrode assembly (e.g., a split-tip electrode assembly) or other ablation member. In some embodiments, the first plurality of thermocouples or other temperature measuring devices and the second plurality of thermocouples or other temperature measuring devices extend up to 1mm beyond the outer surfaces of the first electrode member and the at least one heat transfer member, respectively.

According to some embodiments, a portion of at least one heat transfer member including the second plurality of temperature measurement devices has an outer diameter greater than an outer diameter of the elongate body so as to facilitate a greater insertion depth within the tissue, thereby increasing isolation of the thermocouple or other temperature measurement device from thermal effects of the electrode member(s).

According to several embodiments, a therapy system includes a medical device (e.g., an ablation catheter), a processor, and an energy source. The medical device comprises: the temperature measurement device includes an elongate body having a proximal end and a distal end, an energy delivery member (e.g., an electrode) located at the distal end of the elongate body, a first plurality of temperature measurement devices carried by or located along or within the energy delivery member, and a second plurality of temperature measurement devices located along the elongate body proximal to the electrode. The energy delivery member may be configured to contact tissue of a subject and deliver energy generated by the energy source to the tissue. In some embodiments, the energy is sufficient to at least partially ablate the tissue. In some embodiments, the first plurality of temperature measurement devices is thermally insulated from the energy delivery member and the second plurality of temperature measurement devices is thermally insulated from the energy delivery member. In one embodiment, the second plurality of temperature measurement devices are spaced around the outer surface of the elongated body. The energy source of embodiments of the system may be configured to provide energy to the energy delivery member through one or more conductors (e.g., wires, cables, etc.) extending from the energy source to the energy delivery member.

The processor of an embodiment of the system may be programmed or otherwise configured (e.g., by executing instructions stored on a non-transitory computer-readable storage medium) to receive signals indicative of temperature from each of the temperature measurement devices and determine an orientation of the distal end of the elongate body of the ablation catheter relative to tissue based on the received signals. In some embodiments, the processor may be configured to adjust one or more therapy parameters based on the determined orientation. The one or more treatment parameters may include, among other things, the duration of the treatment, the power of the energy, the target or set point temperature, and the maximum temperature.

In some embodiments, the processor is configured to cause an identification of the determined orientation to be output to the display. The output may include textual information (such as words, phrases, letters, or numbers). In some embodiments, the display comprises a graphical user interface and the output comprises one or more graphical images indicative of the determined orientation.

In some embodiments, the determination of the orientation of the distal end of the elongate body of the medical instrument relative to the tissue is based on a comparison of tissue measurements determined from the received signals relative to each other. The orientation may be selected from one of three orientation options: perpendicular, parallel, and angled or slanted. In one embodiment, the processor is configured to generate an output for terminating the delivery of energy (e.g., an alert for a user to manually terminate energy delivery or a signal for automatically terminating energy delivery) if the determined orientation changes during energy delivery. In some embodiments, the processor may be configured to adjust one or more therapy parameters based on the determined orientation. The one or more treatment parameters may include, among other things, the duration of the treatment, the power of the energy, the target or set point temperature, and the maximum temperature.

According to some embodiments, a therapy system includes a medical instrument (e.g., an ablation catheter) and a processor. The medical device may include: an elongated body having a proximal end and a distal end; an energy delivery member at the distal end of the elongate body, the energy delivery member configured to contact tissue of a subject and deliver energy (e.g., ablation energy) to the tissue; a first plurality of temperature measurement devices located within the energy delivery member; and a second plurality of temperature-measuring devices located along the elongate body proximal to the energy delivery member. The first plurality of temperature measurement devices may be thermally insulated from the energy delivery member and may be spaced apart from each other, and the second plurality of temperature measurement devices may be thermally insulated from the energy delivery member and may be spaced apart around the outer surface of the elongate body.

The processor of an embodiment of the treatment system may be programmed or otherwise configured (e.g., by executing instructions stored on a non-transitory computer-readable storage medium) to receive signals from each of the temperature measurement devices and calculate a peak temperature of tissue at a depth based on the received signals. The peak temperature may include an extreme temperature (e.g., peak or valley/trough temperature, hot or cold temperature, positive peak or negative peak).

According to some embodiments, the processor is configured to calculate a peak temperature of the tissue at a depth by comparing respective temperature measurements determined from the received signals to each other. In some embodiments, the processor is configured to adjust one or more therapy parameters based on the calculated peak temperature, the one or more therapy parameters including a duration of the therapy, a power of the energy, a target temperature, and a maximum temperature.

According to some embodiments, the processor is configured to: an output is generated to automatically terminate energy delivery if the calculated peak temperature exceeds a threshold temperature, or an alert is generated to cause a user to manually terminate energy delivery. In some embodiments, the processor is configured to cause an identification of the calculated peak temperature to be output to the display (e.g., using color, textual information, and/or numerical information).

According to several embodiments, a treatment system includes a medical device (e.g., an ablation catheter) comprising: an elongated body comprising a proximal end and a distal end; an energy delivery member located at the distal end of the elongate body. In one embodiment, an energy delivery member (e.g., an electrode) is configured to contact tissue of a subject and deliver energy (e.g., ablation energy) to the tissue. The medical device comprises: a first plurality of temperature measurement devices located within separate openings or bores formed in the energy delivery member; and a second plurality of temperature-measuring devices located along the elongate body proximal to the energy delivery member. The first plurality of temperature measurement devices may be thermally insulated from the electrode and spaced apart from each other, and the second plurality of temperature measurement devices may be thermally insulated from the electrode. In one embodiment, the second plurality of temperature measurement devices are spaced around the outer surface of the elongated body. The therapy system may also include a processor programmed or otherwise configured (e.g., by executing instructions stored on a non-transitory computer-readable storage medium) to receive signals from each of the temperature measurement devices and determine an estimated location of a peak temperature zone at a depth within the tissue based at least in part on the received signals. In some embodiments, the processor determines individual temperature measurements based on the received signals and compares them to determine an estimated location of the peak temperature. The processor may be configured to adjust one or more therapy parameters based on the estimated location, the one or more therapy parameters including duration, power, target temperature, and maximum temperature. The processor may be further configured to cause an identification of the estimated location to be output to the display. The output may include alphanumeric information and/or one or more graphical images indicating the estimated location of the peak temperature zone.

According to several embodiments, a method of determining a peak temperature of tissue ablated at a depth from a surface of the tissue may comprise: signals indicative of temperature are received from a first plurality of temperature sensors located at a distal end of the ablation catheter. In one embodiment, each of the first plurality of temperature sensors is spaced around the distal end of the ablation catheter. The method also includes receiving signals indicative of temperature from a second plurality of temperature sensors located a distance proximal to the first plurality of temperature sensors. The method further includes determining temperature measurements from signals received from the first plurality of temperature sensors and the second plurality of temperature sensors and comparing the determined temperature measurements to each other. In some embodiments, the method includes applying one or more correction factors to one or more of the determined temperature measurements based at least in part on the comparison to determine a peak temperature. In one embodiment, the method includes outputting the determined peak temperature on a display in a textual, visual, and/or graphical manner. In one embodiment, the method includes adjusting one or more treatment (e.g., ablation) parameters and/or terminating ablation based on the determined hotspot temperature. The second plurality of temperature sensors may be spaced around the circumference of the ablation catheter or other medical device.

According to some embodiments, a method of determining a location of a peak temperature zone within ablated tissue comprises: signals indicative of temperature are received from a first plurality of temperature sensors located at a distal end of the ablation catheter. In one embodiment, each of the first plurality of temperature sensors is spaced around the distal end of the ablation catheter. The method includes receiving signals indicative of temperature from a second plurality of temperature sensors located a distance proximal to the first plurality of temperature sensors. The method further includes determining temperature measurements from signals received from the first plurality of temperature sensors and the second plurality of temperature sensors and comparing the determined temperature measurements to each other. The method may include determining a location of a peak temperature zone of the thermal damage based at least in part on the comparison. In one embodiment, the method includes outputting the determined peak location on a display in a textual, visual, and/or graphical manner. In one embodiment, each of the second plurality of temperature sensors is spaced around a circumference of the ablation catheter.

According to some embodiments, a method of determining an orientation of a distal tip of an ablation catheter relative to tissue in contact with the distal tip comprises: the method includes receiving signals indicative of temperature from a first plurality of temperature sensors located at a distal end of the ablation catheter and receiving signals indicative of temperature from a second plurality of temperature sensors located a distance proximal to the first plurality of temperature sensors. The method further includes determining temperature measurements from signals received from the first and second pluralities of temperature sensors and comparing each of the determined temperature measurements to one another. The method further includes determining an orientation of a distal tip of the ablation catheter relative to tissue in contact with the distal tip based at least in part on the comparison. In one embodiment, the method includes outputting the determined orientation on a display. The output may include textual information or one or more graphical images. Embodiments of the method may also include terminating the energy delivery or generating an output (e.g., an alarm) to signal to the user that the energy delivery should be terminated. In some embodiments, each of the first plurality of temperature sensors is spaced apart around the distal end of the ablation catheter, and each of the second plurality of temperature sensors is spaced apart around the circumference of the ablation catheter.

According to several embodiments, a system for rapidly determining an orientation of an ablation catheter relative to a target region comprises: an ablation catheter comprising an elongate body having a plurality of temperature measuring devices distributed along a distal end of the elongate body and at least one electrode member at the distal end of the elongate body; an energy source configured to apply ablation energy to the electrode member sufficient to ablate target tissue; and at least one processing device. The at least one processing device is configured to, upon execution of certain instructions stored on the computer-readable medium, determine an orientation of the contact surface of the at least one electrode member relative to the target tissue based on the first set of orientation criteria at a plurality of points in time within the first time period.

The contact surface of the at least one electrode member may be an outer distal surface of the at least one electrode member (e.g., a tip electrode member having a flat or rounded outer distal surface). In some embodiments, at least one electrode member is a distal electrode member of a unitized electrode assembly configured for high resolution mapping and radiofrequency energy delivery, the unitized electrode assembly comprising a distal electrode member and a proximal electrode member separated by a gap, such as a unitized electrode assembly described herein. In some embodiments, the at least one processing device is configured to determine the orientation of the contact surface of the at least one electrode member relative to the target tissue based on the second set of orientation criteria at a plurality of time points within a second time period beginning after the end of the first time period. The second set of orientation criteria may be different from the first orientation criteria. In embodiments involving two sets of orientation criteria, the first time period may correspond to a temperature ramp-up phase of temperature rise, while the second time period corresponds to a steady-state phase in which the temperature remains at a steady peak temperature without significant deviation. For example, the first period of time may be between 1 and 20 seconds, between 5 and 13 seconds, between 3 and 15 seconds, or between 5 and 10 seconds after the initial application of ablation energy, as well as overlapping ranges thereof or any value within that range. In some embodiments, the plurality of time points within the first time period and the second time period occur per second; however, other frequencies are possible for the two time periods (e.g., every 100ms, every 500ms, every 1500ms, every 2 seconds, every 3 seconds, every 4 seconds, every 5 seconds). In some embodiments, the frequency of the time points within the second period is longer than the frequency of the time points within the first period.

In some embodiments, the first set of orientation criteria includes time-dependent conditions and/or static conditions, and the second set of orientation criteria consists only of static conditions. The first set of orientation criteria in the temperature ramp-up phase may include a comparison of time-based characteristics of the temperature responses of at least two of the plurality of temperature measurement devices (e.g., a rate of change of temperature over a period of time or a time taken to ramp up from a starting temperature to a certain temperature). For example, the comparison of the time-based characteristics of the temperature responses may include a different comparison between the time-based characteristics of the temperature responses of a proximal set of temperature measurement devices and the time-based characteristics of the temperature responses of a distal set of temperature measurement devices. The at least one processing device may be configured to determine an orientation from a plurality of orientations or alignments, candidates, or options based on the comparison. For example, if the average proximal temperature rise is greater than the average distal temperature rise by a certain factor, this may be an indication that the electrode-tissue orientation is oblique. As another example, a time-related threshold may be used to help determine the orientation during the temperature ramp-up phase. For example, the largest proximal temperature rise may be subtracted from the smallest distal temperature rise, and this value may be compared to a time-dependent threshold. If the threshold is exceeded, it may be an indication that the orientation is a tilt. The second set of orientation criteria may include a comparison of temperature measurements of at least two of the plurality of temperature measurement devices.

Both the first set of orientation criteria and the second set of orientation criteria may involve a first test for a first orientation and if the orientation for the first orientation is not met, a second orientation is tested. If the orientation criteria for the second orientation are not satisfied, the at least one processing device may determine that the ablation catheter is in the third orientation by default if there are only three orientation options. Both the first set of orientation criteria and the second set of orientation criteria may involve testing the orientations in the same order (e.g., tilted, then parallel, then perpendicular) or in a different order. The orientation criteria may vary depending on the order of testing of the orientation options. In some embodiments, the temperature may be continuously increased during a desired period of time, and thus only one set of orientation criteria is used.

According to several embodiments, a system for determining an orientation of an ablation catheter relative to a target region comprises: an ablation catheter comprising an elongate body having a plurality of temperature measurement devices distributed along a distal end of the elongate body; an energy source configured to apply ablation energy sufficient to ablate target tissue to at least one energy delivery member positioned along a distal end of an ablation catheter; and at least one processing device. The at least one processing device is configured to, upon execution of specific instructions stored on the computer-readable medium: obtaining a temperature measurement from each of a plurality of temperature measurement devices at a plurality of points in time; determining, at each point in time, a time-based characteristic of a temperature response of each of the plurality of temperature measurement devices from the obtained temperature measurement; and determining, at each point in time, an orientation of the distal end of the elongate body from one of a plurality of orientation options based at least in part on a comparison of time-based characteristics of temperature responses of at least two of the plurality of temperature measurement devices.

The time-based characteristic of the temperature response may be a rate of change of the temperature measurement between the current point in time and a previous point in time, or an elapsed time between the starting temperature value and a predefined or predetermined increased temperature value. In some embodiments, the time-based characteristic of the temperature response is a difference between a temperature measurement at a current point in time and a temperature measurement at a previous point in time. In some embodiments, the plurality of time points are spaced apart at regular time intervals (e.g., every second). The temperature measurement may be a moving average. In some embodiments, the temperature measurement at the previous point in time is a starting temperature value obtained within five seconds after the initial application of ablation energy by the energy source; however, times other than five seconds may be used (e.g., within ten seconds, within eight seconds, within six seconds, within four seconds, within three seconds, within two seconds, at one second, or within one second). The starting temperature value may be an average of temperature values obtained over a period of time (e.g., an average of temperature values obtained every 100ms from 0 to 1 second after initiating energy delivery).

In various embodiments, the plurality of temperature measurement devices consists of two spaced apart groups of temperature measurement devices. In one embodiment, the temperature measurement device consists of six thermocouples. The six thermocouples may include: a first group of three co-planar thermocouples, and a second group of three co-planar thermocouples spaced proximally of the first group of three thermocouples. Other numbers of temperature measurement devices may be used as desired and/or required.

In several embodiments, the initial orientation is advantageously determined rapidly (e.g., less than 20 seconds, less than 15 seconds, less than 10 seconds, less than 5 seconds) after application of the ablation energy by the energy source. According to several embodiments, the orientation can be determined quickly because the comparison of the temperature response of the temperature measurement device is based on the rate of change rather than on the spread or difference of values after reaching steady state. The plurality of orientation options may include two or three orientations. If two orientation options are possible, this option may consist of a parallel orientation and a perpendicular orientation. If three orientation options are possible, the options may consist of a parallel orientation, a perpendicular orientation, and a tilted (or angled) orientation. In an embodiment involving three orientation options, the at least one processing device is configured to first determine whether the orientation is a tilt orientation based on an orientation criterion defined for the tilt orientation. If the tilt orientation criterion is met, the orientation is determined to be tilt. If the tilt orientation criterion is not satisfied, the at least one processing device is then configured to determine whether the orientation is in a parallel orientation based on the orientation criterion defined for the parallel orientation. If the parallel orientation criterion is met, the orientation is determined to be parallel. If the parallel orientation criterion is not met, the at least one processing device determines by default that the ablation catheter must be in a vertical orientation. Other orders may be used. For example, if only two orientation options are possible, then a perpendicular or parallel condition may be tested first.

According to several embodiments, the at least one processing device is configured to generate an output indicative of the determined orientation. The output may include a graphical icon of the electrode in the determined orientation and/or other visual indicators identifying the determined orientation from the plurality of orientation options. For example, the output may include a graphical user interface including three radio buttons, each radio button being accompanied by a text label for a respective one of the plurality of orientation options, and the visual indicator may indicate or mark the radio button corresponding to the determined orientation.

The orientation criteria may include one or more of the following: a comparison of a relationship between an average rate of change of temperature measurement values of the first plurality of temperature measurement devices and an average rate of change of temperature measurement values of the second plurality of temperature measurement devices, a comparison of a relationship between a maximum rate of change of temperature measurement values of the first plurality of temperature measurement devices and a maximum rate of change of temperature measurement values of the second plurality of temperature measurement devices, a comparison of a relationship between a maximum rate of change of temperature measurement values of the first plurality of temperature measurement devices and a minimum rate of change of temperature measurement values of the second plurality of temperature measurement devices, a comparison of a relationship between a minimum rate of change of temperature measurement values of the first plurality of temperature measurement devices and a maximum rate of change of temperature measurement values of the second plurality of temperature measurement devices, a comparison of a rate of change of temperature measurement values from a previous point in time to a current point in time between at least two of the first plurality of temperature measurement devices, and/or a comparison of a rate of change of temperature measurements from a previous point in time to a current point in time between at least two of the second plurality of temperature measurement devices.

In some embodiments, determining the temperature measurement at each of the plurality of time points for each of the plurality of temperature sensors comprises calculating a moving average at each of the plurality of time points based on the current temperature measurement and one or more previous temperature measurements. Calculating a rate of change between the determined temperature value at each of the plurality of time points and the starting temperature value for each of the plurality of temperature sensors may comprise: the starting temperature value is subtracted from the moving average and divided by the elapsed time from the start of the time period to the current point in time. In some embodiments, the starting temperature value may be determined by: the method further includes receiving signals indicative of temperature from a plurality of temperature sensors distributed along a distal end of the ablation catheter at a first plurality of points in time in a first time period, determining, for each of the plurality of temperature sensors, a temperature measurement at each of the first plurality of points in time, and then calculating a starting temperature value for each of the plurality of temperature sensors based on the determined temperature measurements.

In some embodiments, the plurality of temperature sensors comprises: a first plurality of temperature sensors (e.g., a first co-planar group of three thermocouples or thermistors) located at the distal tip of the ablation catheter, and a second plurality of temperature sensors (e.g., a second co-planar group of three thermocouples or thermistors) located a distance proximal to the first plurality of temperature sensors. In some embodiments, determining the orientation of the distal end of the ablation catheter relative to the target surface based on a comparison of the calculated rates of change of at least two of the plurality of temperature sensors includes determining whether the calculated rates of change satisfy one or more orientation criteria for the respective orientations (e.g., oblique, parallel, or perpendicular). The orientation criteria may be different for each of the orientation options. At least some of the orientation criteria are time-dependent. According to several embodiments, the orientation criteria are empirically determined based on previous data.

According to several embodiments, a method of determining an orientation of a distal end of an ablation catheter relative to a target region comprises: receiving signals indicative of temperature from a plurality of temperature sensors distributed along a distal end of an ablation catheter at a first plurality of points in time over a first period of time; determining, for each of a plurality of temperature sensors, a temperature measurement at each of a first plurality of points in time; determining, at each of a first plurality of time points, an orientation of a distal end of the ablation catheter relative to the target surface based on a first set of orientation criteria applied to the determined temperature measurements; receiving signals indicative of temperature from a plurality of temperature sensors at a second plurality of points in time within a second time period after the first time period; determining, for each of a plurality of temperature sensors, a temperature measurement at each of a second plurality of points in time; and determining an orientation of the distal end of the ablation catheter relative to the target surface at each of the second plurality of time points based on the second set of orientation criteria applied to the determined temperature measurements. In several embodiments, the second set of orientation criteria is different from the first set of orientation criteria. For example, the first set of orientation criteria may include a comparison of time-based characteristics of temperature responses of at least two of the plurality of temperature sensors, and the second set of orientation criteria may include a comparison of temperature measurements of at least two of the plurality of temperature sensors. The first time period may correspond to a temperature ramp-up phase and the second time period may correspond to a steady-state phase. The first set of orientation criteria and the second set of orientation criteria may be determined empirically.

According to several embodiments, a method of determining an orientation of a distal end of an ablation catheter relative to a target region comprises: receiving signals indicative of temperature from a plurality of temperature sensors distributed along a distal end of an ablation catheter at a first plurality of points in time in a first time period; determining, for each of a plurality of temperature sensors, a temperature measurement at each of a first plurality of points in time; determining a starting temperature value for each of a plurality of temperature sensors based on the determined temperature measurements; receiving signals indicative of temperature from a plurality of temperature sensors at a second plurality of points in time in a second time period after the first time period; determining, for each of a plurality of temperature sensors, a temperature measurement at each of a second plurality of points in time; calculating a rate of change between the determined temperature value at each of the second plurality of points in time and a starting temperature value for each of the plurality of temperature sensors; and determining, at each of the second plurality of time points, an orientation of the distal end of the ablation catheter relative to the target surface based on a comparison of the calculated rates of change of at least two of the plurality of temperature sensors. In some embodiments, the method further comprises: the method further includes receiving signals indicative of temperature from the plurality of temperature sensors during a third time period after the second time period, determining a temperature measurement for each of the plurality of temperature sensors, and determining an orientation of the distal end of the ablation catheter relative to the target surface based on a comparison of the temperature measurements for at least two of the plurality of temperature sensors.

According to several embodiments, a system includes at least one signal source configured to deliver at least a first frequency and a second frequency to a pair of electrodes or electrode portions of a combined electrode or electrode assembly. The system also includes a processing device configured to: obtaining impedance measurements while the signal source applies the first frequency and the second frequency to the pair of electrodes, processing electrical (e.g., voltage, current, impedance) measurements obtained at the first frequency and the second frequency, and determining whether the pair of electrodes contacts tissue based on the processing of the electrical (e.g., impedance) measurements. The pair of electrodes may be positioned along the medical device (e.g., at a distal portion of the ablation catheter). The pair of electrodes may comprise radiofrequency electrodes, and the at least one signal source may comprise one, two or more sources of radiofrequency energy.

The signal source may include a first signal source configured to generate, deliver, or apply a signal having a frequency configured for tissue ablation to the pair of electrodes and a second signal source configured to generate, deliver, or apply a signal having a frequency suitable for contact sensing and/or tissue type determination (e.g., whether tissue is ablated or still living) to the pair of electrodes. The first and second signal sources may be integrated within an energy delivery module (e.g., an RF generator) or within an elongate body or handle of a medical device (e.g., an ablation catheter). In some embodiments, the second signal source is within a contact sensing subsystem, which may be a separate and distinct component from the energy delivery module and the medical device, or may be integrated within the energy delivery module or the medical device. In one embodiment, only one signal source is used, which is capable of applying signals having a frequency suitable for ablation or other therapy and signals having a frequency suitable for contact sensing or tissue type determination functions. The frequency suitable for contact sensing or tissue type determination may be within or outside the treatment frequency range. For example, in one non-limiting embodiment, the system includes an energy source configured to generate, deliver, or apply a signal to at least one pair of electrode members (and also to a ground pad or reference electrode) to deliver energy having a frequency configured for tissue ablation or other therapy, and a signal source configured to generate, deliver, or apply a signal to the pair of electrode members (and not to the ground pad or reference electrode) having a frequency suitable for contact sensing and/or tissue type determination (e.g., whether tissue is ablated or still viable). The signal generated by the signal source may comprise a constant current AC excitation signal or an AC voltage excitation signal. The excitation signal may advantageously be outside the frequency range of the ablation frequency and/or the electrographic mapping frequency. Both the energy source and the signal source may be integrated within an energy delivery module (e.g., an RF generator), or one of the sources (e.g., the signal source) may be incorporated within an elongate body or handle of a medical device (e.g., an ablation catheter). In some embodiments, the signal source is within a contact sensing subsystem, which may be a separate and distinct component from the energy delivery module and the medical device, or may be integrated within the energy delivery module or the medical device. In some embodiments, a single source is used that is configured to apply signals having a frequency suitable for ablation or other therapy and configured to apply signals having a frequency suitable for contact sensing or tissue type determination functions. Signals having a therapeutic frequency (e.g., a frequency suitable for ablating cardiac tissue) may also be delivered to the ground pad or the reference electrode.

In some embodiments, the system consists essentially of or includes a medical instrument (e.g., an energy delivery device), one or more energy sources, one or more signal sources, and one or more processing devices. A medical device (e.g., an energy delivery catheter) may include an elongate body having a proximal end and a distal end, and a pair of electrodes or electrode portions (e.g., a combination or composite (such as a split-tip) electrode assembly) located at the distal end of the elongate body. In one embodiment, the pair of electrodes includes or consists essentially of a first electrode on the elongate body and a second electrode positioned adjacent to (e.g., proximal to) the first electrode. The first and second electrodes may be configured to contact tissue of a subject and provide energy to the tissue to heat (e.g., ablate or otherwise treat) the tissue at a depth from a surface of the tissue. In one embodiment, the pair of electrodes includes an electrically insulating gap between the first electrode and the second electrode, the electrically insulating gap including a gap width separating the first electrode and the second electrode. A separator (e.g., a capacitor or an insulating material) may be located within the electrically insulating gap.

One or more signal sources may be configured to deliver signals within a range of frequencies (e.g., frequencies within a radio frequency range). In some embodiments, the processing device is configured to execute specific program instructions stored on a non-transitory computer-readable storage medium to: obtaining an impedance or other electrical measurement when a signal source applies energy of different frequencies within the frequency range to the pair of electrodes, processing the impedance or other electrical measurement obtained at the first and second frequencies, and determining whether at least one of the pair of electrodes (e.g., the most distal electrode) contacts tissue based on the processing of the impedance or other electrical measurement. According to several embodiments, the impedance measurement constitutes a bipolar contact impedance between the pair of electrodes or between the electrode members of the unitized electrode assembly, rather than an impedance between the electrodes and the target tissue. According to several embodiments, impedance or other electrical measurements do not involve passing current to one or more patches or reference electrodes located at a location external to the medical instrument or at a location remote from the target tissue (e.g., at a location on the skin at the neck, torso, and/or legs of the patient).

In some embodiments, the medical device consists essentially of, or comprises, a radiofrequency ablation catheter and first and second electrodes or electrode portions comprising a radiofrequency electrode. The signal source(s) may include a Radio Frequency (RF) generator. In one embodiment, the frequency range delivered by the signal source(s) (e.g., one or more signal sources contacting the sensing subsystem) includes a range of at least between 1kHz and 5MHz (e.g., between 5kHz and 1000kHz, between 10kHz and 500kHz, between 5kHz and 800kHz, between 20kHz and 800kHz, between 50kHz and 5MHz, between 100kHz and 1000kHz, and overlapping ranges thereof). The signal source(s) may also be configured to deliver frequencies below and above this range. The frequency may be at least five or at least ten times greater than the electrographic mapping frequency so as not to interfere with the high resolution mapping images or functions obtained by the first and second electrodes or electrode portions. In one embodiment, the different frequencies at which the impedance measurements are obtained consist of only two discrete frequencies. In another embodiment, the different frequencies include two or more discrete frequencies. In some embodiments, the processing device is configured to obtain the impedance measurement while applying an entire frequency sweep from a minimum frequency to a maximum frequency of the frequency range to the pair of electrodes or the portion of electrodes. As an example, the frequency range is between 5kHz and 1000 kHz. The second frequency may be different from (e.g., higher or lower than) the first frequency. According to several embodiments, the frequency used for contact sensing or determination is outside (e.g., below) the frequency range of the ablation frequency.

The system may include an ablation energy source (e.g., a signal source such as an RF generator) configured to deliver a signal to the pair of electrodes (and possibly also to a ground pad or reference electrode) to generate energy sufficient to ablate or otherwise treat tissue, such as cardiac tissue. In one embodiment, the processing device is configured to adjust one or more energy delivery parameters of the ablation energy based on determining whether at least one of the pair of electrodes is in contact with the tissue, and/or to terminate energy delivery based on determining whether at least one of the pair of electrodes is in contact with the tissue or the contact has been lost. In some embodiments, the source of ablation energy and the at least one signal source comprise a single source. In other embodiments, the signal source comprises a first source and the ablation energy source comprises a second source separate and distinct from the first source. In some embodiments, this processing is performed in the time domain. In some embodiments, this processing is performed in the frequency domain. Portions of this processing may be performed in both the time domain and the frequency domain.

In some embodiments, the processing device is configured to execute specific program instructions stored on a non-transitory computer-readable storage medium to generate an output indicative of contact. The processing device may be configured to cause the generated output to be displayed on a display (e.g., an LCD or LED monitor) in communication with the processing device. In various embodiments, the output includes textual information, quantitative information (e.g., numerical information, a binary assessment of whether contact is present), and/or qualitative information (e.g., color or other information indicative of the level of contact).

According to several embodiments, a system comprises: a signal source configured to deliver a signal having a range of frequencies; and a processing device configured to execute specific program instructions stored on a non-transitory computer readable storage medium to: obtaining impedance (e.g., bipolar contact impedance) or other electrical measurements when a signal source applies energy at different frequencies to a pair of electrodes (e.g., a combination electrode or a compound (e.g., split-tip) electrode assembly), comparing the impedance measurements obtained at the energy at the different frequencies, and determining whether tissue in contact with at least one of the pair of electrodes has been ablated. In some embodiments, the contact determination is made in a frequency range between 5kHz and 1000 kHz. In one embodiment, the different frequencies are made of two discrete frequencies, or in other embodiments, the different frequencies may include two or more discrete frequencies. The processing device may be configured to obtain impedance measurements while applying a full sweep of frequencies from a minimum frequency to a maximum frequency of the frequency range (e.g., 5kHz to 1000kHz) to the pair of electrodes. In some embodiments, one component of the impedance measurement (e.g., the impedance magnitude) is obtained at a first frequency, and a second component of a different impedance measurement (e.g., the phase angle) is obtained at a second frequency. Comparisons of impedance magnitude measurements between the pair of electrodes at two or more different frequencies (e.g., derivatives of impedance with frequency, increments or slopes of impedance with frequency) may also be obtained. The processing device may calculate a weighted combination of the various impedance measurements at two or more different frequencies, and the processing device may use the weighted combination to determine an overall contact level or state. The impedance measurement may be obtained directly or may be calculated based on an electrical parameter measurement, such as a voltage and/or current measurement. According to several embodiments, the impedance measurement comprises a bipolar impedance measurement.

In some embodiments, the processing device is configured to execute specific program instructions stored on the non-transitory computer-readable storage medium to generate an output indicative of the tissue type based on determining whether tissue in contact with at least one of the pair of electrodes has been ablated. The processing device may be configured to cause the generated output to be displayed on a display in communication with the processing device. The output may include one or more of textual information, color or other qualitative information, and numerical information. In various embodiments, the processing device is configured to adjust one or more energy delivery parameters based on the determination of whether tissue in contact with the pair of electrodes has been ablated, and/or to terminate energy delivery based on the determination of whether tissue in contact with the pair of electrodes has been ablated.

According to several embodiments, a system for determining whether a medical instrument is in contact with tissue based at least in part on an impedance measurement comprises: a signal source configured to deliver signals having different frequencies to a pair of electrodes of a medical instrument; and a processing device configured to process the resulting waveform formed across the pair of electrodes to obtain impedance measurements at the first frequency and the second frequency and to determine a ratio between the amplitudes of the impedance at the second frequency and the first frequency. If the determined ratio is below a predetermined threshold indicative of contact, the processing device, when executing the stored instructions on the computer-readable medium, is configured to generate a first output indicative of contact. If the determined ratio is above a predetermined threshold, the processing device is configured to generate a second output indicative of no contact when executing the stored instructions on the computer readable medium. In one embodiment, the signal source comprises a source of radio frequency energy. The first and second frequencies may be between 5kHz and 1000 kHz. In some embodiments, the signal source is configured to generate a signal having a frequency suitable for tissue ablation. In other embodiments, the system includes a second signal source (or ablation energy source) configured to generate a signal having a frequency suitable for tissue ablation. Frequencies suitable for tissue ablation may be between 400kHz and 600kHz (e.g., 400kHz, 450kHz, 460kHz, 480kHz, 500kHz, 550kHz, 600kHz, 400 kHz-500 kHz, 450 kHz-550 kHz, 500 kHz-600 kHz, or overlapping ranges thereof). In various embodiments, the predetermined threshold is a value between 0.5 and 0.9. Processing the waveform may include obtaining voltage and/or current measurements and calculating impedance measurements based on the voltage and/or current measurements or directly obtaining impedance measurements.

A method of determining whether a medical instrument is in contact with a target region (e.g., tissue) based at least in part on an electrical measurement (e.g., impedance measurement) may include: the method includes applying a signal having a first frequency and a second frequency to a pair of electrodes or electrode portions of the medical instrument, processing the resulting waveforms to obtain impedance measurements at the first frequency and the second frequency, and determining a ratio between the second frequency and an amplitude of the impedance at the first frequency. If the determined ratio is below a predetermined threshold indicative of contact, the method includes generating a first output indicative of contact. If the determined ratio is above a predetermined threshold, the method includes generating a second output indicating no contact. The method may further include applying a signal adapted to cause ablation energy to be delivered by the pair of electrodes or electrode portions sufficient to ablate a target region (e.g., cardiac tissue or other body tissue).

According to several embodiments, a system for determining a contact state of a distal end portion of a medical instrument with a target region (e.g., tissue) based at least in part on electrical measurements includes a signal source configured to generate at least one signal having a first frequency and a second frequency to be applied to a pair of electrode members of a unitized electrode assembly. The signal source may be a component of a contact sensing or detection subsystem or an energy delivery module, such as a radio frequency generator. The system also includes a processor or other computing device configured to, upon execution of particular program instructions stored in the memory or in the non-transitory computer-readable storage medium, cause the signal source to generate and apply at least one signal to the pair of electrode members. The signal may be a single multi-tone waveform or signal, or a plurality of waveforms or signals having a single frequency.

The processor may be configured to process the resulting waveforms formed across the pair of electrode members to obtain a first electrical measurement at a first frequency and to process the resulting waveforms formed across the pair of electrode members to obtain a second electrical measurement at a second frequency of the plurality of frequencies. The processor is further configured to: determine an impedance magnitude based on a first electrical measurement (e.g., a voltage and/or current measurement), determine an impedance magnitude and phase based on a second electrical measurement, and calculate a contact indication value indicative of a state of contact between a distal end portion of the medical instrument and the target region based on a criterion that combines: an impedance magnitude based on the first electrical measurement, a ratio of the impedance magnitudes based on the first electrical measurement and the second electrical measurement, and a phase based on the second electrical measurement. The first and second electrical measurements may comprise voltage and/or current measurements or direct impedance measurements between the pair of electrode members. In some embodiments, the first and second electrical measurements do not include a direct measurement of an electrical parameter or a degree of coupling between the electrode and the tissue, but rather a measurement between the two electrode members. The impedance measurement may be calculated based on the voltage and/or current measurements, or may be obtained or measured directly by an instrument or device configured to output the impedance measurement. The impedance measurements may include complex impedance measurements (e.g., impedance magnitude and phase angle measurements or resistance and reactance measurements) made up of real and imaginary components. According to several embodiments, the impedance measurement comprises a bipolar contact impedance measurement between two electrode members.

In some embodiments, the criteria include a weighted combination of an impedance magnitude based on the first electrical measurement, a ratio of impedance magnitudes based on the first electrical measurement and the second electrical measurement, and a phase based on the second electrical measurement. In some embodiments, the criteria include an "if-then" case condition criteria, such as described in conjunction with FIG. 11 and FIG. 11A. In various embodiments, only one impedance measurement or calculation (e.g., only impedance magnitude, only slope between impedance magnitude values, or only phase) or only two types of impedance measurements or calculations are used to determine the contact state.

According to several embodiments, a system for determining whether a medical instrument is in contact with a target region (e.g., tissue) based at least in part on an impedance measurement consists essentially of or includes: a signal source configured to generate one or more signal sources having a first frequency and a second frequency to a pair of electrodes (e.g., located at a distal end of a medical instrument, catheter, or stylet); and a processing device configured to execute specific program instructions stored in the non-transitory computer readable storage medium to process the resulting waveforms formed across the pair of electrodes to obtain impedance measurements at the first frequency and the second frequency. If the impedance magnitude at the first and/or second frequency is above a predetermined threshold indicative of contact, the processing device is configured to generate a first output indicative of contact when executing the stored instructions on the computer-readable storage medium. If the impedance magnitude at the first and/or second frequency is below a predetermined threshold indicative of contact, the processing device is configured to generate a second output indicative of no contact when executing the stored instructions on the computer-readable storage medium. Processing the waveform may include obtaining voltage and/or current measurements and calculating impedance measurements based on the voltage and/or current measurements or directly obtaining impedance measurements.

A method of determining whether a medical instrument is in contact with a target region (e.g., tissue) based at least in part on an impedance measurement includes: delivering at least one signal (e.g., a multi-tone waveform) having a first frequency and a second frequency to a pair of electrodes or electrode portions; and processing the resulting waveforms formed across the pair of electrodes to obtain impedance measurements at the first and second frequencies. If the impedance magnitude at the first frequency and/or the second frequency is above a predetermined threshold indicative of contact, the method includes generating a first output indicative of contact. If the impedance magnitude at the first frequency and/or the second frequency is below a predetermined threshold indicative of contact, the method includes generating a second output indicative of no contact. The method may further include applying a signal adapted to cause ablation energy to be delivered by the pair of electrodes or electrode portions sufficient to ablate or otherwise treat the heart or other body tissue.

Methods of determining whether a medical instrument is in contact with a target region (e.g., tissue) based at least in part on an impedance measurement may include: applying a signal comprising a multi-tone waveform having a first frequency and a second frequency to a pair of electrodes; processing the resulting waveform to obtain impedance measurements at the first frequency and the second frequency; comparing the values of the impedance measurements at the first and second frequencies to a known impedance of the blood or the blood and saline mixture (or other known tissue impedance); comparing the values of the impedance measurements at the first and second frequencies with each other; and generating an output indicative of whether the medical instrument is in contact with the tissue based on each of the comparisons. A system for determining whether a medical instrument is in contact with tissue based at least in part on an impedance measurement may include: a signal source configured to generate a multi-tone waveform or signal having a first frequency and a second frequency to a pair of electrodes (e.g., at the distal end of a combination electrode (such as a split tip electrode) catheter); and a processing device. The processing device may be configured, upon execution of the stored instructions on the computer-readable storage medium, to process the resulting waveform to obtain impedance measurements at the first and second frequencies, compare values of the impedance measurements at the first and second frequencies to a known impedance of the blood or the blood and saline mixture, compare values of the impedance measurements at the first and second frequencies to one another, and/or generate an output indicative of whether the medical instrument is in contact with the tissue based on each of the comparisons. The method may further include applying a signal adapted to cause ablation energy to be delivered by the pair of electrodes or electrode portions sufficient to ablate or otherwise treat the heart or other body tissue.

According to several embodiments, a method of determining whether a medical instrument comprising a pair of electrodes or electrode portions is in contact with a target region (e.g., tissue) based at least in part on an impedance measurement includes: applying at least one signal having a plurality of frequencies (e.g., a multi-tone waveform) to a pair of electrodes of a medical instrument; and processing the resulting waveforms formed across the pair of electrodes to obtain impedance measurements at a first frequency and a second frequency of the plurality of frequencies. If the change in the impedance measurement over the frequency range has a model whose parameter values are indicative of contact, the method includes generating a first output indicative of contact. If the change in the impedance measurement over the frequency range has a model whose parameter values indicate no contact, the method includes generating a second output indicating no contact. The model may include a fitting function or a circuit model, such as that shown in FIG. 5B. The method may further include applying a signal adapted to cause ablation energy to be delivered by the pair of electrodes or electrode portions sufficient to ablate or otherwise treat the heart or other body tissue.

A system for determining whether a medical instrument is in contact with tissue based at least in part on an impedance measurement, comprising: a signal source configured to generate at least one signal having a first frequency and a second frequency to a pair of electrodes; and a processing device. The processing device may be configured, upon execution of the stored instructions on the computer-readable storage medium, to apply at least one signal having a plurality of frequencies to a pair of electrodes of the medical instrument and process a resulting waveform formed across the pair of electrodes to obtain impedance measurements at a first frequency and a second frequency of the plurality of frequencies. The processor is configured to generate a first output indicative of contact if a change in the impedance measurement over the frequency range follows a model whose parameter values are indicative of contact. The processor is configured to generate a second output indicative of no contact if the change in the impedance measurement over the frequency range follows a model whose parameter values are indicative of no contact. Processing the waveform to obtain the impedance measurement may include obtaining a voltage and/or current measurement and calculating the impedance measurement based on the voltage and/or current measurement or directly obtaining the impedance measurement.

According to several embodiments, a method of determining whether tissue has been ablated by an ablation catheter comprising a pair of electrodes is provided. The method comprises the following steps: one or more signals (e.g., multi-tone waveforms) having a first frequency and a second frequency are applied to a pair of electrodes along an ablation catheter, and the resulting waveforms formed across the pair of electrodes are processed to obtain impedance measurements at the first frequency and the second frequency. The method may include evaluating absolute changes in impedance and slopes or ratios between impedances. If the first impedance measurement at the first and/or second frequency is greater than the known impedance level of the blood, and if the ratio of the second impedance measurement to the first impedance measurement is above a predetermined threshold, the method includes generating a first output indicative of the ablated tissue. If the first impedance measurement at the first and/or second frequency is greater than the known impedance level of the blood, and if the ratio of the second impedance measurement to the first impedance measurement is below a predetermined threshold, the method includes generating a second output indicative of living tissue. Processing the waveform to obtain the impedance measurement may include obtaining a voltage and/or current measurement and calculating the impedance measurement based on the voltage and/or current measurement or directly obtaining the impedance measurement. The method may further include applying a signal adapted to cause ablation energy to be delivered by the pair of electrodes or electrode portions sufficient to ablate or otherwise treat the heart or other body tissue.

In some embodiments, the phase of the impedance measurement at the first frequency and/or the second frequency is compared to a known phase response of the blood or the blood and saline mixture, and the phase of the impedance measurement at the first frequency and/or the second frequency is used in conjunction with the amplitude value of the impedance measurement to output an output indicative of whether the medical instrument is in contact with the tissue. A system for determining whether tissue has been ablated by an ablation catheter comprising a pair of electrodes or electrode portions may comprise: a signal source configured to generate at least one signal having a first frequency and a second frequency to a pair of electrodes along an ablation catheter; and a processing device. The processing device may be configured to, upon execution of stored instructions on the computer-readable storage medium, process the resulting waveforms formed across the pair of electrodes to obtain impedance measurements at the first frequency and the second frequency. If the first impedance measurement at the first and/or second frequency is greater than the known impedance level of the blood, and if the ratio of the second impedance measurement to the first impedance measurement is above a predetermined threshold, the processing device is configured to generate a first output indicative of the ablated tissue. If the ratio of the second impedance measurement to the first impedance measurement is below a predetermined threshold, the processor is configured to generate a second output indicative of living (e.g., non-ablated) tissue. Processing the waveform to obtain the impedance measurement may include obtaining a voltage and/or current measurement and calculating the impedance measurement based on the voltage and/or current measurement or directly obtaining the impedance measurement.

Processing the resulting waveform may include applying a transform (e.g., a fourier transform) to the waveform to obtain an impedance measurement. In some embodiments, the first frequency and the second frequency are in a range between 5kHz and 1000 kHz. In one embodiment, the second frequency is higher than the first frequency. Impedance measurements may be obtained simultaneously or sequentially. The second frequency may be at least 20kHz higher than the first frequency. In one embodiment, the first frequency is between 10kHz and 100kHz (e.g., between 10kHz and 30kHz, between 15kHz and 40kHz, between 20kHz and 50kHz, between 30kHz and 60kHz, between 40kHz and 80kHz, between 50kHz and 90kHz, between 60kHz and 100kHz, overlapping ranges thereof, 20kHz, or any value between 10kHz and 100 kHz) and the second frequency is between 400kHz and 1000kHz (e.g., between 400kHz and 600kHz, between 450kHz and 750kHz, between 500kHz and 800kHz, between 600kHz and 850kHz, between 700kHz and 900kHz, between 800kHz and 1000kHz, overlapping ranges thereof, 800kHz, or any value between 400kHz and 1000 kHz). The predetermined threshold may have a value between 0.5 and 0.9. In some embodiments, generating the first output and generating the second output further comprises causing the first output or the second output to be displayed on a display (e.g., via one or more display drivers). The output may include textual information indicative of the contact status, quantitative measurements, and/or qualitative assessments. In some embodiments, the output includes an amount of contact force (e.g., grams of force) corresponding to the level of contact.

A method of determining whether a medical instrument having a pair of electrodes or electrode portions is in contact with a target region (e.g., tissue) based at least in part on an impedance measurement may include: a first impedance measurement is obtained at a first frequency within a frequency range, a second impedance measurement is obtained at a second frequency within the frequency range, and a third impedance measurement is obtained at a third frequency within the frequency range. If the change in the impedance measurement over the frequency range is above a predetermined threshold indicative of contact, the method includes generating a first output indicative of contact. If the change in the impedance measurement over the frequency range is below the predetermined threshold, the method includes generating a second output indicative of no contact. The impedance measurement may be calculated based on voltage and/or current measurements, or may be a directly measured impedance measurement. The method may further include applying a signal adapted to cause ablation energy to be delivered by the pair of electrodes or electrode portions sufficient to ablate or otherwise treat the heart or other body tissue.

The frequency range may be between 5kHz and 5MHz (e.g., between 5kHz and 1000kHz, between 1MHz and 3MHz, between 2.5MHz and 5MHz, or overlapping ranges thereof). In one embodiment, the first frequency is between 10kHz and 100kHz (e.g., between 10kHz and 30kHz, between 15kHz and 40kHz, between 20kHz and 50kHz, between 30kHz and 60kHz, between 40kHz and 80kHz, between 50kHz and 90kHz, between 60kHz and 100kHz, overlapping ranges thereof, 20kHz, or any value between 10kHz and 100 kHz), and the second frequency is between 400kHz and 1000kHz (e.g., between 400kHz and 600kHz, between 450kHz and 750kHz, between 500kHz and 800kHz, between 600kHz and 850kHz, between 700kHz and 900kHz, between 800kHz and 1000kHz, overlapping ranges thereof, 800kHz, or any value between 400kHz and 1000kHz), and the third frequency is between 20kHz and 800 kHz. The predetermined threshold may be a value between 0.5 and 0.9. In some embodiments, generating the first output and generating the second output includes causing the first output or the second output to be displayed on a display. The output may include textual information indicative of the contact. In one embodiment, the output includes a quantitative measurement and/or a qualitative assessment of the contact.

In some embodiments, the distal end portion of the medical device includes a high resolution electrode assembly including a first electrode portion and a second electrode portion (e.g., a composite electrode assembly or a combination radio frequency electrode) spaced apart from and insulated from the first electrode portion. The control unit may include a contact detection subsystem or module configured to receive signals from the high-resolution electrode assembly, and a control unit (e.g., a processor) or separate processor of the contact detection subsystem or module may be configured (e.g., specifically programmed with instructions stored in or on a non-transitory computer-readable medium) for determining a level of contact or a state of contact with tissue (e.g., cardiac tissue) based on the signals received from the high-resolution electrode assembly, and adjusting a reaction force provided by a reaction force (operation force) motor based at least in part on the determined level of contact or state of contact. The control unit may further include a power delivery module configured to apply radio frequency power to the high resolution electrode assembly at a level sufficient to enable ablation of tissue in contact with at least a portion of the distal end portion of the medical device.

In some embodiments, the control unit (e.g., processor) is configured to generate an output indicative of the contact level for display (e.g., via one or more display drivers) on a display coupled to the control unit. In various embodiments, the output is based on a contact function determined based on one or more criteria combining a plurality of electrical parameter measurements (such as voltage measurements, current measurements, or impedance measurements). In one embodiment, the contact function is determined by adding a weighted combination of impedance (e.g., bipolar impedance) measurements measured directly or calculated based on voltage and/or current measurements. In one embodiment, the contact function is based on one or more "if-then" case condition criteria. In one embodiment, the impedance measurement includes one or more of: an impedance magnitude determined by the contact detection subsystem at the first frequency, a ratio of the impedance magnitudes at the first frequency and the second frequency, and a phase of the complex impedance measurement at the second frequency. The second frequency may be higher than the first frequency (e.g., at least 20kHz higher than the first frequency). In some embodiments, the first frequency and the second frequency are between 5kHz and 1000 kHz. In one embodiment, the first frequency is between 10kHz and 100kHz (e.g., between 10kHz and 30kHz, between 15kHz and 40kHz, between 20kHz and 50kHz, between 30kHz and 60kHz, between 40kHz and 80kHz, between 50kHz and 90kHz, between 60kHz and 100kHz, overlapping ranges thereof, 20kHz, or any value between 10kHz and 100 kHz) and the second frequency is between 400kHz and 1000kHz (e.g., between 400kHz and 600kHz, between 450kHz and 750kHz, between 500kHz and 800kHz, between 600kHz and 850kHz, between 700kHz and 900kHz, between 800kHz and 1000kHz, overlapping ranges thereof, 800kHz, or any value between 400kHz and 1000 kHz); however, other frequencies may be used as desired and/or required. In some embodiments, the frequency at which impedance measurements are obtained is outside of the treatment (e.g., ablation) frequency range. In some embodiments, a filter (such as a band pass filter) is used to isolate the treatment frequency range from the impedance measurement frequency range.

In some embodiments, the handle of the medical instrument further comprises a motion detection element (e.g., at least one of an accelerometer and a gyroscope). In some embodiments, the first motor is configured to be actuated only when the motion detecting element is detecting motion of the handle.

According to several embodiments, a method of determining a contact state of a distal portion of a medical instrument with a target region (e.g., tissue) includes: at least one signal having a plurality of frequencies is applied to a pair of electrodes or electrode portions of a unitized electrode assembly positioned along a distal end portion of a medical device. The method comprises the following steps: processing the resulting waveform formed across the pair of electrodes to obtain a first impedance measurement at a first frequency of the plurality of frequencies; and processing the resulting waveform formed across the pair of electrodes to obtain a second impedance measurement at a second frequency of the plurality of frequencies. The method further comprises the following steps: determining a magnitude of the first impedance measurement; determining an amplitude and a phase of the second impedance measurement; and applying a contact function (e.g., via execution of a computer program stored on a non-transitory computer storage medium) to calculate a contact indication value indicative of a state of contact between a distal portion of the medical instrument and the target region (e.g., cardiac tissue). The contact function may be determined by adding a weighted combination of the magnitude of the first impedance measurement, the ratio of the magnitudes of the first and second impedance measurements, and the phase of the second impedance measurement. In various embodiments, the first frequency and the second frequency are different. In one embodiment, the second frequency is higher than the first frequency.

The method may further include generating an output corresponding to the contact indication value for display on a display monitor (e.g., via one or more display drivers). In some embodiments, the output comprises a qualitative and/or quantitative output. The output may include a numerical value between 0 and 1, or between 0 and 1.5, where a value greater than 1 indicates excessive contact. In some embodiments, the output includes a percentage value or number corresponding to the amount of contact force (e.g., grams of contact force). The output may include one or more of a color and/or pattern and/or gauge, bar, or scale indicative of the contact status. The method may further include applying a signal adapted to cause ablation energy to be delivered by the pair of electrodes or electrode portions sufficient to ablate or otherwise treat the heart or other body tissue.

According to several embodiments, a system for determining a contact state of a distal portion of a medical instrument with a target region (e.g., tissue) based at least in part on electrical parameter measurements consists essentially of or includes a signal source configured to generate at least one signal having a first frequency and a second frequency to be applied to a pair of electrode members (e.g., two electrode members separated by a gap) of a unitized electrode assembly. The system also consists essentially of or includes a processing device configured to: (a) causing a signal source to generate and apply at least one signal to the pair of electrode members, (b) processing the resulting waveforms formed across the pair of electrode members to obtain first electrical measurements at a first frequency, (c) processing the resulting waveforms formed across the pair of electrode members to obtain second electrical measurements at a second frequency of the plurality of frequencies, (d) determining an impedance magnitude based on the first electrical measurements, (e) determining an impedance magnitude and phase based on the second electrical measurements, and (f) calculating a contact indication value indicative of a state of contact between a distal end portion of the medical instrument and the target region based on criteria combining: an impedance magnitude based on the first electrical measurement, a ratio of the impedance magnitudes based on the first and second electrical measurements, and a phase based on the second electrical measurement. The electrical measurements may include voltage, current, and/or other electrical parameter measurements from which an impedance measurement (such as impedance magnitude or phase) may be calculated, or the impedance measurement may include a directly obtained impedance measurement. The criteria may include a weighted combination of impedance magnitude based on the first electrical measurement, a ratio of impedance magnitudes based on the first and second electrical measurements, and a phase based on the second electrical measurement, or the criteria may include an "if-then" condition criteria.

In some embodiments, the system further comprises a medical device, which may be a radio frequency ablation catheter. The first frequency and the second frequency may be different. In some embodiments, the second frequency is higher than the first frequency. In some embodiments, the second frequency is lower than the first frequency. In some embodiments, the first frequency and the second frequency are between 5kHz and 1000kHz (e.g., between 5kHz and 50kHz, between 10kHz and 100kHz, between 50kHz and 200kHz, between 100kHz and 500kHz, between 200kHz and 800kHz, between 400kHz and 1000kHz, or overlapping ranges thereof). In various embodiments, the two frequencies are separated in frequency by at least 20 kHz.

In some embodiments, the processor is further configured to, upon execution of particular instructions stored in or on the computer-readable medium, generate an output corresponding to the contact indication value for display on the display monitor. In some embodiments, the output comprises a numerical value between 0 and 1. In some embodiments, the output includes a qualitative output (such as a color and/or pattern indicative of the contact status). In some embodiments, the output comprises one or more of a gauge, a bar, a meter, or a scale. In one embodiment, the output includes a virtual gauge having a plurality of regions (e.g., two, three, four, five, or more than five regions or segments) indicative of varying contact levels or contact states. The multiple regions may be represented in different colors. Each of the plurality of regions may correspond to a different range of values indicative of varying levels of contact.

According to several embodiments, a system for displaying on a patient monitor a contact status of a distal tip of a medical instrument with a target region (e.g., body tissue) includes a processor configured to generate an output for display on the patient monitor. The output may be generated on a graphical user interface on the patient tip. In one embodiment, the output includes a graph showing a contact function indicative of a state of contact between a distal tip of the medical instrument and body tissue calculated by the processing device based at least in part on impedance measurements obtained by the medical instrument. The graph may be a rolling waveform. The output also includes a gauge separate from the map indicating a real-time contact status corresponding to a real-time value of the contact function displayed by the map. The gauge includes a plurality of regions indicative of varying contact conditions. In some embodiments, each of the plurality of regions is optionally displayed in a different color or scale to provide a qualitative indication of the real-time contact status. In one embodiment, the gauge consists of three regions or sections. The three regions may be colored red, yellow and green. In another embodiment, the gauge consists of four regions or sections. The four regions may be colored red, orange, yellow and green. Each of the plurality of regions may correspond to a different range of values indicative of the current contact state. The gauge may include a pointer indicating a level on the gauge corresponding to the real-time value of the contact function. The real-time value may range between 0 and 1 or between 0 and 1.25 or between 0 and 1.5. Values above 1 may generate a "contact alert" to the clinician to prevent excessive contact that may result in perforation of the tissue. For example, the gauge may include a contact indicator of the quality of the tissue-electrode contact calculated based on the bipolar impedance amplitude, the bipolar impedance-frequency slope, and the bipolar impedance phase.

The output may also include other graphs or waveforms of individual components of the impedance measurement (e.g., impedance magnitude and phase) at multiple frequencies or a comparison (e.g., slope) between two impedance measurements (e.g., impedance magnitude at two different frequencies).

In some embodiments, the contact function is calculated based on a weighted combination of: a magnitude of a first impedance measurement at a first frequency, a ratio of the magnitude of the first impedance measurement and a magnitude of a second impedance measurement at a second frequency different from the first frequency, and a phase of the second impedance measurement at the second frequency. In one embodiment, the second frequency is higher than the first frequency. In another embodiment, the second frequency is lower than the first frequency. The first frequency and the second frequency may be between 5kHz and 1000 kHz. In some embodiments, the system further comprises a patient monitor.

According to several embodiments, a system for assessing a level of contact between a distal portion of an ablation catheter having a pair of spaced-apart electrode members of a unitized electrode assembly and a target region (e.g., tissue) includes a signal source configured to generate a signal having at least a first frequency and a second frequency to be applied to the pair of spaced-apart electrode members. The system also includes a processor configured to, upon execution of certain program instructions stored on a computer readable storage medium, measure a network parameter at an input of a network measurement circuit comprising a plurality of hardware components between a signal source and the pair of spaced apart electrode members. The processor may also be configured (e.g., programmed, constructed, or designed, among other things) to: determining a composite effect on the measured network parameter value caused by a hardware component of the network measurement circuit, removing the composite effect to yield a corrected network parameter value between the pair of spaced apart electrode members, and determining the contact level based at least in part on the corrected network parameter value.

In some embodiments, the processor is configured to generate for display an output indicative of the contact level. The signal source may be located within the radiofrequency generator or within the ablation catheter. The processor may be configured to measure the network parameter at least two frequencies (e.g., two frequencies, three frequencies, four frequencies, or more than four frequencies). In some embodiments, the frequency is between 5kHz and 1000 kHz. In embodiments involving two frequencies, the second frequency may be at least 20kHz higher than the first frequency. For example, the first frequency may be between 10kHz and 100kHz and the second frequency between 400kHz and 1000 kHz. The third frequency may be higher than the first frequency and lower than the second frequency (e.g., the third frequency may be between 20kHz and 120 kHz).

The network parameters may include scattering parameters or other electrical parameters (e.g., voltage, current, impedance). The network parameter values may comprise, for example, voltage and current values or impedance values measured directly or determined from voltage and/or current values. The impedance values may include impedance magnitude values and impedance phase values. Impedance amplitude values may be obtained at two or more frequencies, and slopes may be determined between the amplitude values at different frequencies. The impedance phase values may be obtained at one or more frequencies.

According to several embodiments, a method of evaluating a contact level determination of a distal portion of an ablation catheter having a pair of spaced apart electrode members comprises: a network parameter is measured at an input of a network parameter circuit of the hardware component between the signal source and the pair of spaced apart electrode members. The method further comprises the following steps: determining a composite effect on the measured network parameter value determined from the network parameter caused by the hardware component, removing the composite effect to produce a corrected network parameter value between the pair of spaced apart electrode members, and determining the level of contact based at least in part on the corrected network parameter value.

Measuring the network parameter may include measuring the network parameter at a plurality of frequencies. In some embodiments, determining the combined effect on the measured network parameter values caused by the hardware components of the network parameter circuit comprises measuring the network parameter associated with each individual hardware component. In some embodiments, determining the combined effect on the measured network parameter values caused by the hardware components of the network parameter circuit comprises: the network parameters of the individual hardware components are combined into an overall network parameter at a plurality of frequencies. Removing the combined effect so as to isolate the actual network parameter values between the pair of spaced apart electrode members may comprise: the total network parameter is de-embedded from the measured input reflection coefficient to obtain an actual reflection coefficient corresponding to the actual network parameter value. In some embodiments, the method is performed automatically by a processor. The method may further include applying a signal adapted to cause ablation energy sufficient to ablate or otherwise treat the heart or other body tissue to be delivered by the pair of spaced apart electrode members.

According to several embodiments, a system includes a signal source (e.g., a source of radiofrequency energy or an excitation signal) configured to deliver a signal having at least a first frequency and a second frequency to a pair of electrode members (e.g., a pair of spaced apart bipolar electrode members) of a unitized electrode assembly positioned along a distal portion of a medical device (e.g., a radiofrequency ablation catheter). Embodiments of the system also include a processing device (e.g., a special purpose processor) configured to, when executing certain program instructions stored on a computer-readable storage medium: causing a signal source to generate a signal and apply the signal to the pair of electrode members; obtaining an electrical measurement between the pair of electrode members while a signal having at least a first frequency and a second frequency is applied to the pair of electrode members (e.g., a directly measured bipolar contact impedance measurement, or a bipolar contact impedance measurement calculated or otherwise determined from voltage and/or current measurements); processing electrical measurements obtained at a first frequency and a second frequency; and determining whether the unitized electrode assembly is in contact with tissue based on the processing of the electrical measurements. The processing device is configured to generate an output indicative of the contact. The output may include any type of output described herein (e.g., visual, audible), and may be output on a display in communication with the processing device. Embodiments of the system may include a contact sensing subsystem including a signal source and a processing device. The system may also include an ablation energy source configured to generate and apply power to the unitized electrode assembly to ablate the target region, as described herein. The processing device may be configured (e.g., specifically programmed) to: adjusting one or more energy delivery parameters of the ablation energy based on the determination of whether the unitized electrode assembly is in contact with the tissue, and/or terminating energy delivery based on the determination of whether the unitized electrode assembly is in contact with the tissue. In some embodiments, the source of ablation energy and the source of signal comprise a single source. In some embodiments, the signal source comprises a first source and the ablation energy source comprises a second source separate and distinct from the first source. In some embodiments, the contact sensing subsystem is located within the energy delivery device. In some embodiments where the signal source and the ablation energy source are separate sources, the contact sensing subsystem is located within a housing that also houses the ablation energy source.

Embodiments of the system optionally include the medical instrument itself. The medical device may consist essentially of or comprise an ablation catheter comprising an elongate body having a proximal end and a distal end, and wherein the energy delivery apparatus comprises a unitized electrode assembly. The unitized electrode assembly includes a first electrode member positioned along the elongate body (e.g., at the distal tip) and a second electrode member positioned adjacent to the first electrode member (e.g., spaced apart by a gap sufficient to electrically insulate the two electrode members). The two electrode members may be positioned, shaped, sized, and/or designed (e.g., configured) to contact tissue of a subject. The unitized electrode assembly further comprises an electrically insulating gap between the first electrode member and the second electrode member, the electrically insulating gap comprising a gap width separating the first electrode member and the second electrode member.

In some embodiments, the processing device of the system is configured to determine the impedance magnitude based on a first electrical measurement obtained from the signal at the first frequency, and to determine the impedance magnitude and the impedance phase angle value based on a second electrical measurement obtained from the signal at the second frequency. In some embodiments, the processing device is configured to calculate a contact indication value indicative of a contact status between the distal portion of the medical instrument and the target region based on a criterion combining: the impedance magnitude value based on the first electrical measurement, the ratio of the impedance magnitude value based on the first electrical measurement and the impedance magnitude value based on the second electrical measurement, and the impedance phase based on the second electrical measurement. The criteria may include a weighted combination of impedance magnitude based on the first electrical measurement, a ratio of impedance magnitude values based on the first and second electrical measurements, and an impedance phase value based on the second electrical measurement, or the criteria may include an "if-then" condition criteria. In some embodiments, the signals generated and applied to the pair of electrode members do not travel to the patch electrodes away from the target area in order to facilitate bipolar contact measurements between the two electrode members.

As described herein, a processing device of an embodiment of a system may be configured to: measuring a network parameter at an input of a network measurement circuit comprising a plurality of hardware components between a signal source and the pair of electrode members; determining a composite effect on measured network parameter values caused by hardware components of the network measurement circuit; removing the combined effect to obtain a corrected network parameter value between the pair of electrode members; and determining a level of contact between the pair of electrode members and the tissue based at least in part on the corrected network parameter value. The first application frequency may be between 10kHz and 100kHz and the second application frequency may be between 400kHz and 1000 kHz. In some embodiments, the signal source is further configured to generate a signal having a third frequency to be applied to the pair of spaced apart electrode members, and the processing device is further configured to measure the network parameter at the third frequency. In some embodiments, the third frequency is higher than the first frequency and lower than the second frequency. In various embodiments, the third frequency is between 20kHz and 120 kHz. The network parameter may be a scattering parameter or an impedance parameter. The network parameter values may be impedance values consisting of bipolar impedance magnitude values, bipolar impedance phase values, and/or bipolar slope values between impedance magnitude values at different frequencies.

According to several embodiments, a kit comprises: a radio frequency generator comprising an ablation energy source; an ablation catheter including a pair of electrode members separated by a gap positioned along a distal portion of the ablation catheter; and a contact sensing subsystem including a signal source configured to generate and apply signals having at least two different frequencies to the pair of electrode members and a processor configured to determine a level of contact between the pair of electrode members and a target tissue based at least in part on electrical measurements between the pair of electrode members while the signals having at least two different frequencies are being applied.

The contact sensing subsystem of the kit may be housed within the radiofrequency generator, or may be a separate component from the radiofrequency generator. The kit may optionally include a cable for connecting the ablation catheter to the radio frequency generator and/or for connecting the ablation catheter to the contact sensing subsystem. The radio frequency generator may include an integrated display, and the contact sensing subsystem may be configured to generate an output to the display indicative of the level of contact.

According to some embodiments, the ablation system consists essentially of: a catheter, an ablation member (e.g., an RF electrode, a composite (e.g., split tip) electrode, another type of high resolution electrode, etc.), an irrigation conduit extending through the interior of the catheter to or near the ablation member, at least one electrical conductor (e.g., a wire, cable, etc.) for selectively activating the ablation member, and at least one heat transfer member that places at least a portion of the ablation member (e.g., a proximal portion of the ablation member) in thermal communication with the irrigation conduit, at least one thermal shunt member configured to effectively transfer heat away from the electrode and/or tissue being treated, and a plurality of temperature sensors (e.g., thermocouples) positioned along two different longitudinal locations of the catheter, wherein the temperature sensor is thermally isolated from the electrode and configured to detect a temperature of tissue at a depth.

According to several embodiments, a system for compensating for drift of electrode-tissue contact impedance values over time caused by changes in blood impedance includes or consists essentially of a signal source configured to deliver signals to a first set of electrodes positioned along a distal portion of a medical instrument (e.g., an RF ablation catheter) configured to be positioned in contact with a target body tissue (e.g., heart tissue) and at least one processing device. At least one processing device is communicatively coupled to the signal source.

In some embodiments, the at least one processing device is configured to, upon execution of specific program instructions stored on the non-transitory computer-readable storage medium: the method includes determining a reference impedance value (e.g., a bipolar impedance value) when applying a signal having at least one frequency (e.g., one frequency or two frequencies) to a second set of electrodes that are not in contact with the target body tissue, adjusting a contact impedance value (e.g., a bipolar impedance value) obtained when applying the signal having at least one frequency to the first set of electrodes based on the reference impedance value, and calculating a contact indication value (e.g., no contact, poor contact, medium contact, good contact) indicating a level of contact between a distal end portion of the medical instrument and the target body tissue using the adjusted contact impedance value.

In some embodiments, the signal source is configured to deliver signals having at least a first frequency to a first set of electrode members positioned along the distal end portion of the medical instrument configured to be in contact with the target body tissue and to a second set of electrode members that are less likely to be in contact with the target body tissue, and the at least one processing device is configured to, upon execution of specific program instructions stored on the non-transitory computer-readable storage medium: the method includes causing a signal source to generate and apply a signal to a second set of electrodes, determining at least one reference impedance value between the second set of electrodes while applying a signal having at least a first frequency to the second set of electrodes, causing the signal source to generate and apply a signal to the first set of electrodes, determining at least one contact impedance value between the first set of electrodes, adjusting the at least one contact impedance value based on the at least one reference impedance value, and calculating a contact indicator value indicative of a level of contact between a distal portion of the medical instrument and a target body tissue using the at least one adjusted actual impedance value.

The first set of electrodes may comprise a bipolar electrode pair. The bipolar electrode pair may be a proximal electrode member and a distal electrode member of a unitized electrode assembly configured for both high-resolution mapping and tissue ablation. The second set of electrodes may include a pair of reference electrodes (or three, four, or more electrodes) located at a position along the medical instrument proximal to the first set of electrodes. For example, the pair of electrodes may include a pair of spaced apart ring electrodes that are used for mapping in addition to reference measurements to correct for drift. In some embodiments, the second set of electrodes comprises a pair of reference electrodes or other measurement devices on a device separate from the medical instrument. The signal delivered by the signal source may have at least one frequency (e.g., one frequency, two different frequencies, three different frequencies) configured to facilitate an electrical measurement (e.g., a direct impedance measurement or an impedance value obtained from a voltage and/or current measurement) that is in turn used to facilitate an electrode-tissue contact assessment (e.g., a qualitative assessment of whether contact is made or the state or level of contact).

In some embodiments, the reference impedance value (e.g., a bipolar impedance value) is calculated from one or more electrical measurements (e.g., at least one voltage measurement and at least one current measurement) obtained using a pair of electrodes that are not in contact with the target body tissue. In some embodiments, the second set of electrodes is the same set of electrodes as the first set of electrodes, but the reference measurements or values are obtained at times when the first set of electrodes is not in contact with the target body tissue. In some embodiments involving a pair of spaced apart ring electrodes as the second set of electrodes, a distal one of the ring electrodes is separated from a proximal one of the first set of electrodes by a distance of between 2mm and 5mm, and a distance between a proximal edge of the distal one of the ring electrodes and a distal edge of the proximal one of the ring electrodes is between 1mm and 3 mm.

In some embodiments, the reference impedance value comprises: a first reference bipolar impedance value for the impedance magnitude at the first frequency, a second reference bipolar impedance value for the slope between the impedance magnitude at the first frequency and the impedance magnitude at the second frequency, and a third reference bipolar impedance value for the phase at the second frequency. In such embodiments, the at least one processing device may be configured to: the first bipolar contact impedance value is adjusted based on the first reference bipolar impedance value, the second bipolar contact impedance value is adjusted based on the second reference bipolar impedance value, and the third bipolar contact impedance value is adjusted based on the third reference bipolar impedance value. The at least one processing device may be further configured to calculate a contact indication value using the adjusted first, second, and third bipolar contact impedance values.

In some embodiments, the first set of electrodes comprises a pair of electrode members of a unitized electrode assembly. The unitized electrode assembly may include a first electrode member positioned along the elongate body and a second electrode member positioned adjacent the first electrode member, wherein the first and second electrode members are configured to contact tissue of a subject. An electrically insulating gap is located between the first electrode member and the second electrode member, the electrically insulating gap comprising a gap width separating the first electrode member and the second electrode member. A filtering element (e.g., a capacitor) may be located within the gap width.

The signal source may include a radio frequency energy source configured to generate a signal having a single frequency or a signal at a plurality of different frequencies (e.g., a first frequency and a second frequency). The first and second frequencies may be between 5kHz and 1000 kHz. In some embodiments, the second frequency is greater than the first frequency.

In some embodiments, a system for correcting or accounting for drift includes an ablation energy source configured to generate and apply power to a first set of electrodes (e.g., a unitized electrode assembly) for ablating target body tissue. The at least one processing device may be further configured to generate an output indicative of the level of contact based on the calculated contact indication value and cause the output to be displayed on a display in communication with the at least one processing device. The ablation energy source and the signal source may consist of a single energy source, and may be separate and distinct sources. In some embodiments, the system includes a contact sensing subsystem that includes (e.g., resides within or is communicatively coupled to) a signal source and/or at least one processing device. In some embodiments, the contact sensing subsystem is housed within a housing of the radiofrequency energy generator.

According to several embodiments, a method of compensating for (e.g., correcting for or accounting for) drift in electrode-tissue contact impedance values over time caused by changes in blood impedance (e.g., due to introduction of fluid during an ablation procedure) comprises or consists essentially of: determining a reference impedance value based on electrical measurements obtained using a pair of electrode members positioned along the medical instrument when the electrode members are in contact with blood; determining a bipolar contact impedance value using the pair of electrode members when the electrode members are positioned in contact with target tissue at the target tissue ablation site; and adjusting the bipolar contact impedance value based on the determined reference impedance value, resulting in an adjusted bipolar contact impedance value that compensates for drift in the bipolar contact impedance value caused by changes in blood impedance over time. The method may further include determining that the one or more measurement devices are not in contact with the tissue. In some embodiments, the step of adjusting the contact impedance value comprises determining a ratio (or other relationship) between the determined reference impedance value or a drift in the determined reference impedance value and the bipolar contact impedance value or a drift in the bipolar contact impedance value, and applying a correction factor or a scaling value based on the determined ratio (or other relationship).

According to several embodiments, a method of compensating for drift in electrode-tissue contact impedance values over time caused by changes in blood impedance comprises or consists essentially of: the method may include determining a reference impedance value based on electrical measurements obtained using one or more measurement devices in contact with blood but not tissue, determining a contact impedance value (e.g., a bipolar impedance value) using a pair of electrode members of a unitized electrode assembly located at a distal end portion of a medical device in contact with target tissue at a target tissue ablation site, and adjusting the contact impedance value based on the determined reference impedance value, resulting in an adjusted contact impedance value that compensates for drift in the contact impedance value caused by changes in blood impedance and/or resistivity over time. The electrical measurements include at least one voltage measurement and at least one current measurement. The step of determining a reference impedance value based on electrical measurements obtained using one or more measurement devices in contact with blood adjacent to the target tissue ablation site but not in contact with tissue may comprise: the method further includes positioning the pair of electrode members of the unitized electrode assembly at a location so as not to contact tissue, and determining a reference impedance value based on electrical measurements obtained using the pair of electrode members of the unitized electrode assembly. In some implementations, the one or more measurement devices include two spaced apart ring electrodes located at a position along the medical instrument proximal to the pair of electrode members of the unitized electrode assembly. The method may further include calculating a contact indication value indicative of a qualitative assessment of contact using the adjusted contact impedance value.

According to several embodiments, a method of compensating for a drift in an electrode-tissue contact impedance value (e.g., a bipolar impedance value) over time caused by a change in blood impedance includes or consists essentially of: the method includes determining a reference impedance value (e.g., a bipolar impedance value) using a pair of reference electrodes when the pair of reference electrodes are in contact with blood but not in contact with tissue, determining a contact impedance value (e.g., a bipolar impedance value) using a pair of electrode members of a unitized electrode assembly located at a distal portion of a medical device in contact with target tissue at a target tissue ablation site, and adjusting the contact impedance value based on the determined reference impedance value to yield an adjusted contact impedance value that compensates for drift in the contact impedance value caused by changes in blood resistivity or impedance over time.

In some embodiments, the step of determining the reference impedance value includes calculating the reference impedance value (e.g., a bipolar impedance value) from one or more electrical measurements (e.g., at least one voltage measurement and at least one current measurement) obtained using the pair of reference electrodes. The pair of reference electrodes may include two spaced apart ring electrodes located at a position along the medical instrument proximal to the pair of electrode members of the unitized electrode assembly. The distal electrode of the ring electrodes may be separated from the proximal electrode of the pair of electrode members of the unitized electrode assembly by a distance of between 2mm and 5 mm. The distance between the proximal edge of the distal one of the ring electrodes and the distal edge of the proximal one of the ring electrodes may be between 1mm and 3 mm.

In some embodiments, the step of determining the reference impedance value comprises: determining a first reference bipolar impedance value for an impedance magnitude at which a signal having a first frequency is applied to a pair of reference electrodes; determining a second reference bipolar impedance value for a slope between an impedance magnitude when a signal having a first frequency is applied to the pair of reference electrodes and an impedance magnitude when a signal having a second frequency is applied to the pair of reference electrodes; and determining a third reference bipolar impedance value for a phase at which a signal having a second frequency is applied to the pair of reference electrodes. In some embodiments, the step of determining a bipolar contact resistance value comprises: determining a first bipolar contact impedance value for an impedance magnitude at which a signal having a first frequency is applied to the unitized electrode assembly; determining a second bipolar contact impedance value for a slope between an impedance magnitude when a signal having a first frequency is applied to the unitized electrode assembly and an impedance magnitude when a signal having a second frequency is applied to the unitized electrode assembly; a third bipolar contact impedance value is determined for a phase at which a signal having a second frequency is applied to the unitized electrode assembly. In some embodiments, the step of adjusting the bipolar contact resistance value comprises: the method further includes adjusting the first bipolar contact impedance value based on the first reference bipolar impedance value, adjusting the second bipolar contact impedance value based on the second reference bipolar impedance value, and adjusting the third bipolar contact impedance value based on the third reference bipolar impedance value. The method may further include calculating a contact indication value using the adjusted first, second and third bipolar contact resistance values, or calculating a contact indication value indicative of a qualitative assessment of contact using the adjusted bipolar contact resistance values.

According to several embodiments, a method for facilitating assessment of a property of contact between a distal end portion (e.g., a tip electrode or other energy delivery member) of a medical instrument (e.g., an ablation catheter) and body tissue (e.g., cardiac tissue) includes: an output indicative of a property of contact between a distal portion (e.g., a tip electrode) of an ablation catheter or other medical device and body tissue is generated based on bipolar measurements (e.g., bipolar cardiac tissue voltage measurements, frequency measurements, and/or bipolar contact impedance measurements obtained between two electrode members of a composite tip electrode spaced apart by a gap distance and electrically coupled via a filtering element such as a capacitor) prior to applying power or energy (e.g., ablation RF power or energy) to the body tissue sufficient to treat or condition the tissue using the ablation catheter or other medical device. The method may further comprise: an output indicative of a property of contact between a distal portion of the ablation catheter and the body tissue is generated based on temperature readings obtained from a plurality of temperature sensors positioned along a distal tip of the ablation catheter. The plurality of temperature sensors may include: a first plurality of temperature sensors positioned along a distal surface of the distal tip electrode member, and a second plurality of temperature sensors located at or adjacent (e.g., near) a proximal end (e.g., edge) of the proximal electrode member.

In some embodiments, the step of generating an output indicative of a property of contact between the distal portion of the ablation catheter and the body tissue based on the temperature readings comprises: a graphical representation of the distal portion of the ablation catheter is generated for display on a display device (e.g., a display screen of the RF generator or another display device separate from the RF generator) operatively coupled to the ablation catheter. The graphical representation of the distal portion of the ablation catheter may be a two-dimensional or three-dimensional image or graphic. The graphical representation may be continuously updated to provide real-time information to the clinician to facilitate real-time contact assessment. For example, the graphical representation may be updated every millisecond, every few milliseconds, every 100 milliseconds, every 500 milliseconds, every second, or at other frequencies as desired and/or required.

In some implementations, the graphical representation of the distal portion of the ablation catheter includes separate zones corresponding to general areas on the ablation catheter surrounding each of the first plurality of temperature sensors and each of the second plurality of temperature sensors. In such implementations, the step of generating an output indicative of a property of contact between the distal portion of the ablation catheter and the body tissue based on the temperature readings may include: associating a color with each of the temperature readings and filling each of the zones with the color. In other implementations, the step of generating an output indicative of a property of contact between the distal portion of the ablation catheter and the body tissue based on the temperature readings comprises: temperature values at a plurality of locations along a distal portion of an ablation catheter are determined, and colors are associated with the temperature values at the plurality of locations and pixels having colors for the plurality of locations are generated. Such implementations may include: the temperature values are interpolated at locations between the plurality of locations, a color is associated with each of the interpolated temperature values, and a pixel having the color is generated. Associating a color with each of the temperature readings may include determining a stored color value (e.g., stored in a memory or a lookup table) associated with a value of each of the temperature readings.

In some embodiments, the method further comprises generating for display an output indicative of the determined orientation of the distal portion of the ablation catheter relative to the body tissue. The method may include generating an alarm if one of the temperature readings exceeds a threshold temperature. In some embodiments, the method comprises: storing in a memory an output indicative of a property of a contact at one or more instances in time at which ablation power having a frequency in a range of ablation frequencies was applied to the composite-tip electrode assembly, and/or storing in a memory a determined orientation indicative of the one or more instances in time.

In some embodiments, the ablation catheter includes a third electrode spaced proximally from the proximal electrode member of the composite-tip electrode assembly. In such embodiments, the step of generating an output indicative of a property of contact between the distal end portion of the ablation catheter and the body tissue based on the bipolar measurements between the electrode members may comprise: obtaining bipolar voltage measurements indicative of local tissue voltages between each of three pairs of combinations of the distal tip electrode member, the proximal electrode member, and the third electrode, and determining whether the orientation of the distal end portion of the ablation catheter relative to the body tissue is parallel or perpendicular based at least in part on the obtained bipolar voltage measurements. The output indicative of the property of contact between the distal end portion of the ablation catheter and the body tissue based on the bipolar measurements between the electrode members may include: a graphical representation of the distal portion of the ablation catheter in the determined orientation. Determining whether the orientation of the distal portion of the ablation catheter relative to the body tissue is parallel or perpendicular comprises: comparing bipolar voltage measurements between the distal tip electrode member and the proximal electrode member of the composite tip electrode assembly with bipolar voltage measurements between the proximal electrode member and the third electrode of the composite tip electrode assembly, wherein if the two bipolar voltage measurements are substantially equal, the orientations are determined to be parallel, otherwise the orientations are determined to be perpendicular. The method may further comprise, or alternatively comprise, converting the obtained voltage measurements from the time domain to the frequency domain to calculate a frequency measurement corresponding to each of the obtained voltage measurements, wherein the step of determining whether the orientation of the distal portion of the ablation catheter relative to the body tissue is parallel or perpendicular is based at least in part on the frequency measurements.

In some implementations, the method includes generating an output that displays a current maximum voltage measurement of the obtained voltage measurements, wherein the current maximum voltage measurement includes one of a maximum amplitude and a maximum pulse width or a composite thereof. The method may further comprise, or alternatively comprise: generating an output that displays a current maximum frequency measurement of the calculated frequency measurements; and/or generating an output indicative of the completion of lesion formation when the magnitude of the maximum voltage measurement is determined to no longer change over time (e.g., by no more than 10% over at least five seconds).

According to several embodiments, a method for displaying a visual representation to facilitate contact assessment during an ablation procedure includes: for a period of time that ablation energy is applied to tissue by the ablation catheter, temperature data is obtained from a first plurality of temperature sensors located at a distal tip of the ablation catheter and from a second plurality of temperature sensors spaced apart from the first plurality of temperature sensors along the ablation catheter. The method further comprises the following steps: a visual representation is generated for display on a display device operatively coupled to the ablation catheter, wherein the visual representation includes graphical information indicative of temperature data obtained from the first and second pluralities of temperature sensors. The graphical information may include color outputs indicative of temperature data for each of the first plurality of temperature sensors and each of the second plurality of temperature sensors. The visual representation may further indicate an orientation of the distal tip of the ablation catheter relative to the tissue determined based on the temperature data. In some embodiments, the method is performed continuously as ablation energy is applied to the tissue by the ablation catheter, thereby facilitating real-time contact assessment and lesion formation assessment by the clinician. The visual representation may be a graphical image of the distal portion of the ablation catheter. The graphical image may be a two-dimensional or three-dimensional image. In some implementations, the graphical image of the distal portion of the ablation catheter is adapted to rotate to indicate a real-time orientation of the ablation catheter relative to the tissue, wherein the orientation is determined based on the temperature data. The color output may vary in color for different values of the temperature data to provide a visual representation of the current temperature level associated with each of the temperature sensors. The method may include storing the visual representation or information underlying the visual representation in a memory for later access.

According to several embodiments, a method for indicating a property of contact between a distal end portion (e.g., a distal tip electrode) of an ablation catheter or other medical device and body tissue (e.g., heart tissue) includes determining whether ablation energy (or power) is being delivered to the body tissue by the ablation catheter. If it is determined that ablation energy (or power) is not being delivered, the method includes acquiring bipolar voltage measurements between pairs of spaced-apart electrodes positioned along a distal portion of the ablation catheter. For example, the spaced apart electrodes may include: a distal electrode member of the composite-tip electrode assembly located at the distal tip of the ablation catheter, a proximal electrode member of the composite-tip electrode assembly located along the ablation catheter and proximally spaced from the distal electrode member by a gap, and a third electrode member proximally spaced from the proximal electrode member of the composite-tip electrode assembly. The method further includes generating an output indicative of a property of contact between the distal portion of the ablation catheter and the body tissue based at least in part on the bipolar voltage measurements (e.g., a comparison of relative values between the respective bipolar voltage measurements). If it is determined that ablation energy has been delivered to the body tissue through the ablation catheter, the method includes: receiving signals from a plurality of temperature sensors spaced apart from one another along a length of an ablation catheter, the signals including real-time temperature data for each of the plurality of temperature sensors; calculating a temperature measurement for each of a plurality of temperature sensors from the real-time temperature data; and generating a graphical representation of the distal portion of the ablation catheter including an output indicative of a property of contact of the distal portion of the ablation catheter with the body tissue (e.g., an output indicative of the calculated temperature measurements of each of the temperature sensors).

Determining whether ablation energy is being delivered may include determining which mode an energy delivery module (e.g., an RF generator) is in based on a data flow menu or other means. In some embodiments, the plurality of temperature sensors comprises: a first plurality of temperature sensors positioned along a distal face of a distal electrode member of the composite tip electrode assembly, and a second plurality of temperature sensors positioned along or adjacent to an end of a proximal electrode member of the composite tip electrode assembly. The graphical representation of the distal portion of the ablation catheter may include a color output indicative of a current temperature associated with each of the temperature sensors based on the calculated temperature measurements, wherein the color output changes in color from light to dark as the temperature value of the calculated temperature measurements increases. The method may further include causing a graphical representation of the distal portion of the ablation catheter to be rotated to indicate a current orientation of the distal portion relative to the body tissue, wherein the current orientation is determined based on the calculated temperature measurements. The method may further include storing information indicative of the calculated temperature measurements at one or more time instances when ablation energy is delivered by the ablation catheter in a memory.

According to several embodiments, a method for indicating a property of contact between a distal tip of an ablation catheter and body tissue includes determining whether ablation energy is being delivered to the body tissue by the ablation catheter. If it is determined that ablation energy is not being delivered, the method includes obtaining a bipolar impedance value between two electrode members of the composite-tip electrode assembly, and outputting a contact indication value indicative of a level of contact based on the bipolar impedance value. If it is determined that ablation energy is being delivered to the body tissue by the ablation catheter, the method includes: receiving signals from a plurality of temperature sensors spaced apart from one another along a length of an ablation catheter, the signals including real-time temperature data for each of the plurality of temperature sensors; calculating a temperature measurement for each of a plurality of temperature sensors from the real-time temperature data; and outputting, for display on a display device, a graphical user interface including information indicative of the calculated temperature measurements of each of the temperature sensors. Determining whether ablation energy is being delivered may include determining which mode an energy delivery module (e.g., an RF generator) is in based on a data flow menu or other means.

In some embodiments, the bipolar impedance value includes components of a complex impedance (e.g., impedance magnitude and impedance phase angle or resistance and reactance) between two electrode members of a composite-tip electrode assembly. In some embodiments, the plurality of temperature sensors comprises: a first plurality of temperature sensors positioned along a distal face of a distal electrode member of the composite tip electrode assembly, and a second plurality of temperature sensors positioned along or adjacent to an end of a proximal electrode member of the composite tip electrode assembly.

In some implementations, the step of outputting for display on the display device a graphical user interface includes: generating a visual representation of a distal tip of the ablation catheter, the visual representation including separate zones corresponding to each of the temperature sensors, wherein each of the separate zones includes a color indicative of a current temperature associated with each of the temperature sensors based on the calculated temperature measurements. In other implementations, the graphical representation includes a single continuous electrode pattern that is pixelated and divided into grids, where each grid has a color indicative of temperature within an area of the grid. Interpolation algorithms or techniques may be used to determine temperature values at locations between locations of known temperature.

In some embodiments, the method includes causing a graphical representation of a distal portion of the ablation catheter to be rotated to indicate a current orientation of the distal tip relative to the body tissue, wherein the current orientation is determined based on the calculated temperature measurements. The step of outputting a graphical user interface for display on a display device may further comprise outputting a visual representation of the plane of the body tissue on the display. In some embodiments, the step of outputting a graphical user interface for display on a display device further comprises: outputting a visual representation indicative of a property of the predicted lesion underlying the visual representation of the plane of the body tissue based at least in part on the determined orientation of the distal tip relative to the body tissue and the calculated temperature measurement. The visual representation indicative of the nature of the predicted lesion may be an outline of the boundary of the predicted lesion. The method may include storing information indicative of the calculated temperature measurements at one or more time instances when ablation energy is delivered by the ablation catheter in a memory.

According to several embodiments, a method for indicating a property of contact between a distal tip of an ablation catheter and body tissue based at least in part on temperature measurements received from a plurality of temperature sensors spaced apart along a length of the ablation catheter comprises: receiving signals from a plurality of temperature sensors spaced apart from one another along a length of an ablation catheter; calculating a temperature measurement for each of the temperature sensors from the received signals; and outputting, for display, a graphical user interface including information indicative of the calculated temperature measurements of each of the temperature sensors, wherein the information indicative of the calculated temperature measurements facilitates determining a property of contact between a distal tip of the ablation catheter and the body tissue.

According to several embodiments, a system for generating an output to facilitate determining a property of contact between a medical instrument and body tissue during an ablation procedure comprises: an ablation catheter and a graphical user interface system including at least one processing device. The ablation catheter may include: a compound tip electrode comprising a distal tip electrode member and a proximal electrode member spaced apart from the distal tip electrode member by a gap distance; a first plurality of temperature sensors positioned along the distal face of the distal tip electrode member and configured to obtain data indicative of a temperature of each of the first plurality of temperature sensors; and a second plurality of temperature sensors positioned along the ablation catheter at or near the proximal end of the proximal electrode member and configured to obtain data indicative of a temperature of each of the second plurality of temperature sensors. The at least one processing device is configured to receive data indicative of the temperature of each of the first plurality of temperature sensors and each of the second plurality of temperature sensors and generate a graphical output for display on a display device operatively connected to the at least one processing device. The graphical output includes a visual representation indicative of real-time temperatures of each of the first plurality of temperature sensors and each of the second plurality of temperature sensors so as to facilitate evaluation of a property of contact between the composite tip electrode and the body tissue. The graphical output may include a visual representation (e.g., as determined using an interpolation algorithm or technique) indicative of the real-time temperature at locations along the composite tip electrode between the locations of the temperature sensors. In some embodiments, the graphical output further comprises a visual representation of an orientation of the distal portion of the ablation catheter relative to the body tissue, wherein the orientation is determined by the at least one processing device based on data indicative of the temperatures received from the first and second plurality of temperature sensors.

The at least one processing device may be configured to generate an alert upon determining that a real-time temperature of any of the first plurality of temperature sensors or the second plurality of temperature sensors is above a predetermined threshold temperature. In some embodiments, the first plurality of temperature sensors comprises or consists of three thermocouples spaced about the longitudinal axis of the ablation catheter, and the second plurality of temperature sensors comprises or consists of three thermocouples spaced about the longitudinal axis of the ablation catheter. The graphical output may be a two-dimensional or three-dimensional visual image representing the distal portion of the ablation catheter. The visual image may comprise separate discrete regions for each of the first plurality of temperature sensors and each of the second plurality of temperature sensors, or a single continuous image of the catheter tip that is pixelated to continuously display temperature values across all or a substantial portion of the catheter tip surface. In some embodiments, the visual representation of the real-time temperature of each of the first plurality of temperature sensors and each of the second plurality of temperature sensors includes a color corresponding to the real-time temperature of each respective temperature sensor. An interpolation algorithm or technique may be performed to interpolate the real-time temperatures at locations between the temperature sensors such that the temperatures are represented over the entire tip electrode or a substantial portion of the tip electrode. In some implementations, the color changes from light to dark in color as the temperature value increases. For example, a first color may be associated with a first range of lowest temperature values, a second color may be associated with a second range of moderate temperature values, and a third color may be associated with a third range of highest temperature values. In some implementations, the graphical output further includes: a first visual representation configured to indicate a real-time temperature of each of the zones corresponding to the first plurality of temperature sensors; and a second visual representation configured to indicate a real-time temperature of each of the zones corresponding to the second plurality of temperature sensors.

According to several embodiments, a graphical user interface system for displaying information to facilitate determining a property of contact between a medical instrument and body tissue during an ablation procedure includes at least one processing device configured to: receiving data indicative of a temperature of each of a first plurality of temperature sensors located at a distal tip of an ablation catheter; receiving data indicative of a temperature of each of a second plurality of temperature sensors located a distance proximal to the first plurality of temperature sensors along a length of the ablation catheter; generating a graphical output indicative of real-time temperatures of each of the first plurality of temperature sensors and each of the second plurality of temperature sensors based on the received data; and generating a graphical output indicative of an orientation of a distal tip of the ablation catheter relative to the body tissue. The graphical user interface system also includes a display device operatively coupled to the at least one processing device. The display device is configured to (i) display a graphical output indicative of the real-time temperature of each of the first and second plurality of temperature sensors, and (ii) display a graphical output indicative of the orientation of the distal tip of the ablation catheter relative to the body tissue.

In some implementations, the graphical output indicative of the orientation of the distal tip of the ablation catheter relative to the body tissue includes a two-dimensional image or a three-dimensional image representing the distal tip of the ablation catheter oriented relative to the visual representation of the tissue plane. The at least one processing device may be configured to generate an alert upon determining that a real-time temperature of any of the first plurality of temperature sensors or the second plurality of temperature sensors is above a predetermined threshold temperature. In some embodiments, the at least one processing device is configured to automatically adjust or terminate the ablation process upon determining that the real-time temperature of any of the first plurality of temperature sensors or the second plurality of temperature sensors is above a predetermined threshold temperature. The at least one processing device may be configured to store the generated graphical output at one or more time instances during the ablation procedure in a memory operatively coupled to the at least one processing device. In some implementations, the at least one processing device is configured to store real-time temperature values of one or more of the first plurality of temperature sensors and the second plurality of temperature sensors at one or more time instances during the ablation procedure in a memory operatively coupled to the at least one processing device.

According to several embodiments, a method for facilitating assessment of a property of contact between a distal tip of an ablation catheter and body tissue comprises: for a period of time that ablation energy is being applied to tissue by the ablation catheter, temperature data is obtained from a first plurality of temperature sensors located at a distal tip of the ablation catheter and from a second plurality of temperature sensors spaced apart from the first plurality of temperature sensors along the ablation catheter. The method further comprises the following steps: a temperature value is determined at the location of each of the first plurality of temperature sensors and at the location of each of the second plurality of temperature sensors based on the temperature data. The method further comprises the following steps: interpolated temperature values are calculated for a plurality of locations along the distal tip of the ablation catheter between at least one of the first plurality of temperature sensors and at least one of the second plurality of temperature sensors. The method may further comprise: a visual representation of the distal tip of the ablation catheter is generated, the visual representation including graphical information indicative of temperature values at the location of each of the first plurality of temperature sensors and at the location of each of the second plurality of temperature sensors and indicative of interpolated temperature values. In some implementations, the graphical information includes color output. The visual representation may further indicate a real-time orientation of the distal tip of the ablation catheter relative to the tissue, the real-time orientation being determined based on the temperature values determined by the first and second plurality of temperature sensors.

In some embodiments, the method further comprises: based on the determined temperature values and/or the interpolated temperature values, a percentage of a surface area of the distal tip of the ablation catheter in contact with the tissue is determined (e.g., calculated). For example, determining the percentage of surface area of the distal tip of the ablation catheter in contact with the tissue may include: the percentage of the surface area of the distal tip of the ablation catheter that is greater than the predetermined threshold temperature is determined based on the temperature values (determined directly from the temperature measurements and/or interpolated from known temperature measurements). The method may further comprise: an index indicative of lesion volume is calculated based at least in part on a duration (e.g., a duration of an ablation procedure at a particular instance in time) and a determined percentage of a surface area of a distal tip of an ablation catheter in contact with tissue at the instance in time. The method may further include generating an output indicative of the index for display. The output may be a digital output and/or a qualitative output (e.g., color or color change). In some embodiments, the method comprises: automatically terminating the application of the radiofrequency energy using the ablation catheter when the index is equal to or above a predetermined value. The method may include generating a user alert when the index equals or exceeds a predetermined value. The alert may be one of an audible alert, a visual alert, and a tactile (e.g., vibratory) alert.

According to several embodiments, a method of facilitating assessment of lesion formation based at least in part on temperature measurements along an electrode of an ablation catheter comprises: obtaining temperature data from a plurality of temperature sensors positioned along an electrode of an ablation catheter; determining a temperature value at the location of each of the plurality of temperature sensors based on the temperature data; calculating interpolated temperature values for a plurality of locations along the electrode between the plurality of temperature sensors; calculating a percentage of a surface area of the electrode that is equal to or higher than a predetermined temperature indicative of lesion formation based on the determined temperature value and the interpolated temperature value; calculating an index indicative of lesion volume based at least in part on the duration and the calculated percentage of the surface area of the electrode that is equal to or higher than the predetermined temperature; and generating an output of the index for display.

The step of obtaining temperature data from a plurality of temperature sensors positioned along an electrode of an ablation catheter may comprise: temperature data is obtained from at least one temperature sensor (e.g., one, two, or three thermocouples) located at the proximal end of the electrode and temperature data is obtained from at least one temperature sensor (e.g., one, two, or three thermocouples) located at the distal end of the electrode. In some embodiments, the step of calculating interpolated temperature values for a plurality of locations along the electrode between the plurality of temperature sensors comprises: bilinear interpolation or other interpolation algorithms or techniques are performed.

According to several embodiments, a method of facilitating assessment of lesion formation comprises: the method includes generating an output indicative of a maximum local tissue voltage measurement obtained between pairs of electrodes axially spaced along a distal portion of an ablation catheter, displaying the output on a display, and updating the display in real-time. The maximum local tissue voltage measurement may be a composite measurement based on a combination of voltage amplitude and pulse width. The method may further or alternatively comprise: the tissue voltage measurement in the time domain is converted to a frequency measurement in the frequency domain and an output indicative of the maximum frequency measurement is generated. Lesion formation may be determined by observing the output generated over time, and delivery of ablation energy may be terminated by the clinician when lesion formation is determined.

Even though only a single processor is described, any of the methods described in the summary above or the detailed description below, or portions thereof, may be performed by one or more processing devices. Any of the drift correction methods described herein can be automatically performed by at least one processing device of a contact sensing subsystem of an energy delivery system. The processing device(s) (e.g., processor or controller) may be configured to perform the operations recited herein when executing instructions stored in memory or in a non-transitory storage medium. The terms "processor," "processing device," and "controller" may be substituted with various forms of words, and are not limited to a single device, but may include multiple processors, processing devices, or controllers in communication with one another (e.g., operating in parallel). The methods outlined above and set forth in further detail below may describe certain actions taken by a practitioner; however, it should be understood that they may also include instructions for these actions by another party. For example, an action such as "terminate energy delivery" includes "instruct to terminate energy delivery". Other aspects of embodiments of the invention will be discussed in the following portions of the specification. With respect to the figures, elements from one figure may be combined with elements from other figures.

Drawings

These and other features, aspects, and advantages of the present application are described with reference to the drawings of certain embodiments, which are intended to illustrate and not to limit the concepts disclosed herein. The drawings are provided for purposes of illustrating the concepts of at least some of the embodiments disclosed herein and may not be drawn to scale.

Fig. 1 schematically illustrates one embodiment of an energy delivery system configured to selectively ablate or otherwise heat target tissue of a subject;

FIG. 2 illustrates a side view of a system catheter including a high resolution tip design according to one embodiment;

FIG. 3 shows a side view of a system catheter including a high resolution tip design according to another embodiment;

FIG. 4 shows a side view of a system catheter including a high resolution tip design according to yet another embodiment;

fig. 5 shows an embodiment of a catheter of the system comprising two high resolution part electrodes, each consisting of separate parts circumferentially distributed on the catheter shaft;

fig. 6 schematically shows an embodiment of a high-pass filter element consisting of coupling capacitors. The filtering element may be incorporated into a catheter of a system that includes a high resolution tip design;

fig. 7 schematically shows an embodiment of four high-pass filter elements comprising coupling capacitors. The filtering elements may be operatively coupled to separate electrode portions of the system catheter electrode, such as those shown in fig. 5, over an operating RF frequency range;

FIG. 8 illustrates an embodiment of an EKG obtained from the high resolution tip electrode system disclosed herein that is configured to detect whether an ablation procedure has been adequately performed;

fig. 9 illustrates a perspective view of a catheter of an ablation system including an electrode and a thermal shunt network for facilitating heat transfer to an irrigation conduit during use, in accordance with an embodiment;

FIG. 10 shows a partial exposed view of the system of FIG. 9;

fig. 11 illustrates a perspective view of a catheter of an ablation system including an electrode and a thermal shunt network for facilitating heat transfer to an irrigation conduit during use, in accordance with another embodiment;

fig. 12 illustrates a cross-sectional view of a catheter of an ablation system including an electrode and a thermal shunt network for facilitating heat transfer to an irrigation conduit during use, in accordance with an embodiment;

FIG. 13 illustrates a partial cross-sectional perspective view of an embodiment of a catheter of an ablation system including an open irrigation cooling system;

FIG. 14 illustrates a partial cross-sectional perspective view of one embodiment of a catheter of an ablation system including a closed irrigation cooling system;

FIG. 15 shows a partial cross-sectional perspective view of another embodiment of a catheter of the ablation system;

fig. 16A illustrates a side perspective view of a distal end of one embodiment of a composite (e.g., split-tip) RF ablation system including a heat transfer (e.g., thermal shunt) member;

FIG. 16B shows a partial cross-sectional perspective view of the system of FIG. 16A;

fig. 16C illustrates a partial cross-sectional perspective view of another embodiment of an ablation system including a composite electrode and a heat transfer (e.g., thermal shunt) member;

fig. 17A illustrates a side perspective view of a distal end of one embodiment of a composite (e.g., split tip) RF ablation system including a heat transfer (e.g., thermal shunt) member and a fluid outlet extending through a proximal electrode or slug (slug);

FIG. 17B shows a partial cross-sectional perspective view of the system of FIG. 17A;

fig. 18A shows a perspective view of a distal portion of an open irrigated ablation catheter having a plurality of temperature measurement devices according to one embodiment;

fig. 18B and 18C show perspective and cross-sectional views, respectively, of a distal portion of an open irrigated ablation catheter having a plurality of temperature measurement devices according to another embodiment;

fig. 18D shows a perspective view of a distal portion of an ablation catheter having a plurality of temperature measurement devices according to another embodiment;

fig. 18E and 18F illustrate perspective and cross-sectional views, respectively, of a distal portion of an ablation catheter showing isolation of a distal temperature measurement device from an electrode tip, according to one embodiment.

Fig. 19A shows a perspective view of a distal portion of a closed irrigated ablation catheter having a plurality of temperature measurement devices according to one embodiment;

fig. 19B and 19C show perspective and cross-sectional views, respectively, of a distal portion of a closed irrigated ablation catheter having a plurality of temperature measurement devices according to another embodiment;

fig. 19D shows a perspective view of a distal portion of an open irrigated ablation catheter including a non-split tip or other non-composite design according to one embodiment;

fig. 20 shows a cross-sectional perspective view of an embodiment of a catheter comprising a layer or coating along the exterior of a thermal shunt member or portion.

Fig. 21A schematically illustrates a distal portion of an open irrigated ablation catheter in contact with tissue to be ablated in a vertical orientation and a lesion formed using the ablation catheter according to one embodiment;

fig. 21B schematically illustrates a distal portion of an open irrigated ablation catheter in contact with tissue to be ablated in a parallel orientation and a lesion formed using the ablation catheter according to one embodiment;

FIG. 22A is a graph illustrating that the temperature of the damage peak can be correlated to the temperature of the temperature measurement device by a correction factor or function, according to one embodiment;

FIG. 22B is a graph showing estimated peak temperatures determined by an embodiment of an ablation catheter having multiple temperature measurement devices as compared to actual tissue measurements at various depths within tissue;

fig. 23A and 23B show graphs showing temperature measurements obtained by a plurality of temperature measurement devices for embodiments of ablation catheters in parallel and angled orientations, respectively;

fig. 23C illustrates an embodiment of a process of determining an orientation of a distal end of an ablation catheter based, at least in part, on temperature measurements obtained by a plurality of temperature measurement devices of an embodiment of the ablation catheter;

23D and 23E illustrate an embodiment of a process for determining the orientation of the distal end of an ablation catheter;

23F-1, 23F-2, and 23F-3 illustrate example embodiments of an output indicative of a determined orientation;

FIG. 24 schematically illustrates one embodiment of variable frequencies applied to the high resolution tip or compound electrode design of FIG. 2 to determine whether the tip electrode is in contact with tissue;

FIG. 25A is a graph showing normalized electrical resistance of blood/saline and tissue over a range of frequencies;

FIG. 25B is a diagram of a four tone (four tone) waveform for impedance measurement;

FIG. 25C is a graph of impedance versus frequency with tones (tones) at four frequencies;

FIG. 25D schematically illustrates one embodiment of a contact sensing subsystem configured to perform a contact sensing function while simultaneously taking Electrogram (EGM) measurements, in accordance with one embodiment;

FIG. 26A shows the zero crossings of the frequency spectrum and is used to show that switching between frequencies can be designed to occur at the zero crossings to avoid interference of the EGM frequencies;

FIG. 26B schematically illustrates one embodiment of a circuit model for describing the behavior of the impedance of tissue or blood/saline combination as measured across two electrodes or electrode portions;

figure 26C schematically illustrates one embodiment of a circuit configured to switch between the contact sensing circuitry in a standby mode and the radio frequency energy delivery circuitry in a therapy mode, in accordance with one embodiment;

FIG. 27 schematically illustrates one embodiment of a circuit configured to perform a contact sensing function while delivering radio frequency energy, in accordance with one embodiment;

FIG. 28 is a graph of the impedance of an LC circuit element over a range of frequencies;

FIG. 29 is a graph showing resistance or impedance magnitude, value of ablated tissue, living tissue, and blood over a range of frequencies;

FIG. 30 is a graph showing the phase of impedance values for ablated tissue, living tissue, and blood over a range of frequencies;

FIG. 31 illustrates one embodiment of a sensing algorithm that utilizes impedance magnitude, ratio of impedance magnitude at two frequencies, and impedance phase data to determine contact status and tissue status;

FIG. 32 illustrates an embodiment of a contact criteria process, and FIG. 32A illustrates an embodiment of a sub-process of the contact criteria process of FIG. 32;

FIG. 33 illustrates an embodiment of a graphical user interface indicating display of an output of tissue contact of a high resolution combined electrode device;

FIG. 34A shows a schematic diagram of possible hardware components of a network measurement circuit;

FIG. 34B shows a schematic diagram of an embodiment of an auto-calibration circuit configured to calibrate (e.g., automatically) a network measurement circuit to eliminate the effect of one or more hardware components present in the circuit;

FIG. 34C shows a schematic representation of one embodiment of an equivalent circuit model for a hardware component present in an impedance measurement circuit;

FIG. 35 illustrates an embodiment of an EKG obtained from the high resolution tip electrode system disclosed herein that is configured to detect whether an ablation procedure has been adequately performed;

fig. 36A and 36B illustrate different embodiments of target anatomical regions being ablated and graphical representations of ablation data and/or information;

figure 37A illustrates one embodiment of a graphical representation configured to provide data and/or information related to a particular ablation along a target portion of a subject's anatomy;

fig. 37B illustrates another embodiment of a graphical representation configured to provide data and/or information related to a particular ablation along a target portion of the anatomy of a subject;

fig. 38 and 39 illustrate another embodiment of a graphical representation configured to provide data and/or information related to a particular ablation along a target portion of a subject's anatomy;

40A and 40B illustrate different embodiments of 3D tissue maps that have been enhanced by the obtained high resolution data;

fig. 41A shows an embodiment of an ablation catheter in which a first set of electrodes at the distal tip of the ablation catheter are in contact with tissue and a second set of electrodes spaced proximally of the first set of electrodes are not in contact with tissue; and

fig. 41B schematically illustrates an embodiment of an electrical circuit connection between an electrode member of the ablation catheter of fig. 41A and a contact sensing subsystem or module of an energy delivery system.

FIG. 42A is a flow diagram of a hybrid contact evaluation method according to one embodiment.

FIG. 42B is a flow diagram of a hybrid contact evaluation method according to one embodiment.

Fig. 43A, 43B, 44A, 44B, 44C, and 44D illustrate an embodiment of a screen display or graphical user interface that provides a graphical output of real-time information that facilitates intuitive tip-to-tissue contact assessment during an ablation or other treatment session. Color versions of the screen displays of fig. 44A-44D are also provided.

Fig. 45 shows a distal portion of an embodiment of an ablation catheter having a plurality of spaced-apart electrodes configured to facilitate mixed contact assessment before and during delivery of ablation energy.

Fig. 46A, 46B, 47A, and 47B illustrate an embodiment of a screen display or graphical user interface that provides a graphical output of real-time information that facilitates intuitive tip-to-tissue contact assessment before and during ablation or other treatment progression, according to a hybrid contact assessment implementation using the ablation catheter of fig. 45.

Fig. 48 illustrates a partial perspective view of one embodiment of a catheter of an ablation system.

Fig. 49A and 49B illustrate an embodiment of a graphical representation of an electrode assembly configured to provide data and other information to a user.

FIG. 50 illustrates one embodiment of a graphical representation of an electrode assembly configured to provide data and other information to a user.

51A-51D illustrate various embodiments of graphical representations of electrode assemblies configured to provide data and other information to a user.

FIG. 52 illustrates one embodiment of a graphical representation of an electrode assembly configured to provide data and other information to a user.

Fig. 53A-53F illustrate various embodiments of graphical representations of electrode assemblies configured to provide data and other information to a user.

Fig. 54A-54D illustrate various embodiments of graphical representations of electrode assemblies configured to provide data and other information to a user.

Detailed Description

According to some embodiments, successful electrophysiological procedures require accurate knowledge about the anatomical substrate being targeted. In addition, it may be desirable to evaluate the outcome of an ablation procedure within a short period of time after it is performed (e.g., to confirm that a desired clinical outcome is achieved). Typically, ablation catheters include only regular mapping electrodes (e.g., ECG electrodes). However, in some embodiments, it may be desirable for such catheters to incorporate high-resolution mapping capabilities. In some embodiments, the high-resolution mapping electrodes may provide more accurate and detailed information about the anatomical substrate and about the results of the ablation process. For example, such high resolution mapping electrodes may allow an Electrophysiology (EP) practitioner to assess the morphology of an electrogram, its amplitude and width, and/or determine changes in pacing thresholds. According to some arrangements, morphology, amplitude, and/or pacing threshold are accepted as reliable EP markers that provide useful information about the outcome of ablation. Thus, a high resolution electrode is defined as any electrode(s) capable of delivering ablation or other energy to tissue that is capable of transferring heat to/from such tissue while obtaining accurate mapping data of adjacent tissue, and includes, but is not limited to, composite (e.g., split tip) RF electrodes, other closely oriented electrodes or electrode portions, and/or the like.

According to some embodiments, the present application discloses devices, systems and/or methods that include one or more of the following features: high resolution electrodes (e.g., split tip electrodes), a thermal shunt concept to help dissipate heat away from the electrodes and/or tissue of the subject being treated, a plurality of temperature sensors positioned along the exterior of the device to, among other things, determine the temperature at a depth of the subject, and contact sensing features to help determine whether the device is contacting the target tissue and to help determine the extent to which the device is contacting the target tissue.

Several embodiments of the invention are particularly advantageous as they include one, several or all of the following advantages: (i) providing the ability to obtain accurate tissue mapping data using the same electrode that delivers ablation energy, (ii) reducing proximal edge heating, (iii) reducing the likelihood of charring (char) or thrombosis, (iv) providing feedback that can be used to adjust the ablation process in real time, (v) providing non-invasive temperature measurements, (vi) eliminating the need for radiometers (radiometries); (vii) providing tissue temperature monitoring and feedback during irrigated or non-irrigated ablation; (viii) providing various forms of output or feedback to a user; (ix) provide a safer, more reliable ablation procedure, (x) confirmation of actual tissue contact is easily probed; (xi) Confirmation of contact with ablated and non-ablated (living) tissue is easily explorable; (xii) Low cost because the present invention does not require any special sensors; (xiii) No use of distal patch electrode(s) for tissue contact sensing or detection is required; (xiii) More reliable contact indication or assessment; and/or (xiv) ablation duration is reduced for the entire ablation treatment process and/or for each ablation location (e.g., less than 80%, less than 75%, less than 70%, less than 65%, less than 60% compared to existing ablation catheter systems).

High resolution electrode

Fig. 1 schematically illustrates one embodiment of a treatment (e.g., energy delivery) system 10, the treatment system 10 being configured to selectively ablate, stimulate, condition, and/or otherwise heat or treat a target tissue (e.g., cardiac tissue, pulmonary veins, other vessels or organs, etc.) although certain embodiments disclosed herein are described with reference to ablation systems and methods, any system and method may be used to stimulate, condition, heat, and/or affect tissue with or without partial or complete ablation, as desired or required. As shown, the system 10 may include a medical instrument 20 (e.g., a catheter), the medical instrument 20 including one or more energy delivery members 30 (e.g., radiofrequency electrodes) along a distal end of the medical instrument 20. The medical device may be sized, shaped, and/or otherwise configured to be passed endoluminally (e.g., intravascularly) through a subject being treated. In various embodiments, the medical device 20 includes a catheter, shaft, wire, and/or other elongate device. In other embodiments, rather than positioning the medical instrument intravascularly, the medical instrument is positioned extravascularly via laparoscopic or open surgical procedures. In various embodiments, the medical device 20 includes a catheter, shaft, wire, and/or other elongate device. In some embodiments, one or more temperature sensing devices or systems 60 (e.g., thermocouples, thermistors, radiometers, etc.) may be included at the distal end of the medical instrument 20, or along the elongate axis of the medical instrument 20 or in the handle of the medical instrument 20. The term "distal end" or "distal tip" does not necessarily denote a distal tip. The distal end or distal tip may mean the distal tip or distal portion of the medical instrument 20. As used herein, the term "proximal" refers to a direction toward an end of a medical device adapted to be held by a clinician, and as used herein, the term "distal" refers to a direction away from the clinician toward an end of the medical device adapted to be positioned within the body of a subject in use. The medical device 20 may optionally include a mapping electrode (e.g., a proximal ring electrode).

In some embodiments, the medical instrument 20 is operably coupled to one or more devices or components. For example, as shown in fig. 1, the medical device 20 may be coupled to a delivery module 40 (such as an energy delivery module). According to some arrangements, the energy delivery module 40 includes an energy generating device 42, the energy generating device 42 configured to selectively energize (energize) and/or otherwise activate the energy delivery member(s) 30 (e.g., radio frequency electrodes) positioned along the medical instrument 20. In some embodiments, for example, the energy generating device 42 includes one or more signal sources, such as a radio frequency generator, an ultrasonic energy source, a microwave energy source, a laser/light source, another type of energy source or generator, and the like, and combinations thereof in other embodiments, the energy generating device 42 is replaced with a fluid source, such as a cryogenic fluid or other fluid that regulates temperature, or the energy generating device 42 is used in addition to a fluid source, such as a cryogenic fluid or other fluid that regulates temperature. Likewise, a delivery module (e.g., delivery module 40) as used herein may also be a cryogenic device or other device configured for thermal regulation.

With continued reference to the schematic diagram of fig. 1, energy delivery module 40 may include one or more input/output devices or components 44, such as a touch screen device, a screen or other display, a controller (e.g., buttons, knobs, switches, dials, etc.), a keypad, a mouse, a joystick, a touchpad, or other input device, etc. Such devices may allow a physician or other user to input information to system 10 and/or receive information from system 10. In some embodiments, the output device 44 may include a touch screen or other display that provides tissue temperature information, contact information, other measurement information, and/or other data or indicators (e.g., on one or more graphical user interfaces generated by the processor 46) that may be used to adjust a particular treatment session. The input/output devices or components 44 may include an electrophysiology monitor and/or a mapping or navigation system. In some embodiments, the input devices or components are integrated into the output devices or components. For example, a touch screen input interface or input keypad or knob or switch may be integrated into the display monitor or energy delivery module 40 (e.g., generator or control unit).

According to some embodiments, energy delivery module 40 includes a processor 46 (e.g., a processing or control device), which processor 46 is configured to adjust one or more aspects of treatment system 10. Delivery module 40 may also include a memory unit or other storage device 48 (e.g., a non-transitory computer-readable medium), which memory unit or other storage device 48 may be used to store operating parameters and/or other data related to the operation of system 10. In some embodiments, processor 46 includes or is in communication with a contact sensing and/or tissue type detection module or subsystem. The contact sensing subsystem or module may be adapted to determine whether the energy delivery member(s) 30 of the medical instrument 20 are in contact with tissue (e.g., contact sufficient to provide effective energy delivery). In some embodiments, the processor 46 is configured to determine whether tissue in contact with the one or more energy delivery member(s) 30 has been ablated or otherwise treated. In some embodiments, the system 10 includes a contact sensing subsystem 50. The contact sensing subsystem 50 may be communicatively coupled to the processor 46 and/or include a separate controller or processor and memory or other storage medium. The contact sensing subsystem 50 may perform both contact sensing and tissue type determination functions. The contact sensing subsystem 50 may be a separate, stand-alone sub-component of the system (as schematically shown in fig. 1), or may be integrated into the energy delivery module 40 or the medical instrument 20. Additional details regarding the touch sensing subsystem are provided below. The tissue type detection module or subsystem may be adapted to determine whether the tissue is live or ablated. In some embodiments, the processor 46 is configured to automatically adjust the delivery of energy from the energy generating device 42 to the energy delivery member 30 of the medical instrument 20 based on one or more operating schemes. For example, the energy provided to energy delivery member 30 (and thus the amount of heat transferred to or from the target tissue) may be adjusted based on, among other things, the detected temperature of the tissue being treated, whether it is determined that the tissue has been ablated, or whether energy delivery member 30 is determined to be in "sufficient" contact or contact above a threshold level with the tissue to be treated.

According to some embodiments, the energy delivery system 10 may include one or more temperature detection devices, such as reference temperature devices (e.g., thermocouples, thermistors, radiometers, etc.) and/or the like. For example, in some embodiments, the device further includes one or more temperature sensors or other temperature measurement devices to help determine (e.g., detect) a peak (e.g., high or peak, low or trough, etc.) temperature of the tissue being treated (e.g., at a depth (e.g., relative to the tissue surface)) to detect the orientation of the treatment or monitoring portion of the medical instrument (e.g., the distal portion of the catheter including the high resolution electrode assembly). In some embodiments, temperature sensors (e.g., thermocouples) located at, along, and/or near the ablation member (e.g., RF electrodes) can help determine whether contact is being made (and/or the degree to which such contact is being made) between the ablation member and the target tissue. In some embodiments, such peak temperatures may be determined without the use of a radiometer. Additional details regarding the use of temperature sensors (e.g., thermocouples) to determine peak tissue temperatures and/or to confirm or assess tissue contact are provided herein.

Referring to fig. 1, the energy delivery system 10 includes an irrigation fluid system 70 (or is configured to be placed in fluid communication with the irrigation fluid system 70). In some embodiments, such a fluid system 70 is at least partially separate from the energy delivery module 40 and/or other components of the system 10, as shown in fig. 1. However, in other embodiments, the irrigation fluid system 70 is at least partially incorporated into the energy delivery module 40. The irrigation fluid system 70 may include one or more pumps or other fluid transfer devices configured to selectively move a fluid (e.g., a biocompatible fluid such as saline) through one or more lumens or other channels of the catheter 20. Such fluids may be used to selectively cool energy delivery member 30 during use (e.g., transfer heat away from energy delivery member 30). In other embodiments, the system 10 does not include the flushing fluid system 70.

Fig. 2 illustrates one embodiment of a distal end of a medical instrument (e.g., a catheter or other elongate member) 20. As shown, the medical instrument (e.g., catheter) 20 may include a high resolution combined electrode (e.g., split tip) design such that there are two adjacent electrodes or two adjacent electrode members or portions 30A, 30B separated by a gap G. According to some embodiments, the relative lengths of the different electrodes or electrode portions 30A, 30B may vary, as depicted in the configuration of fig. 2. For example, the length of the proximal electrode 30B can be between 1 and 20 times the length of the distal electrode 30A (e.g., 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-16, 16-17, 17-18, 18-19, 19-20, values between the aforementioned ranges, etc.), as desired or required. In other embodiments, the length of the proximal electrode 30B can be greater than 20 times (e.g., 20-25, 25-30, greater than 30 times, etc.) the length of the distal electrode 30A. In still other embodiments, the distal electrode 30A and the proximal electrode 30B are approximately equal in length. In some embodiments, the distal electrode 30A is longer (e.g., 1 to 20 times longer, such as, for example, 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-16, 16-17, 17-18, 18-19, 19-20, values between the aforementioned ranges, etc.) than the proximal electrode 30B.

In some embodiments, the distal electrode or electrode portion 30A has a length of 0.5mm-0.9 mm. In some embodiments, the length of the distal electrode or electrode portion 30A is between 0.1mm and 1.51mm (e.g., 0.1-1.0, 0.1-0.2, 0.2-0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6, 0.6-0.7, 07.0-0.8, 0.8-0.9, 0.9-1.0, 1.0-1.1, 1.1-1.2, 1.2-1.3, 1.3-1.4, 1.4-1.51mm, values between the foregoing ranges, etc.). In other embodiments, the length of the distal electrode or electrode portion 30A is greater than 1mm or 1.51mm, as desired or required. In some embodiments, the proximal electrode or electrode portion 30B has a length of 2 to 4mm (e.g., 2-2.5, 2.5-3, 3-3.5, 3.5-4mm, lengths in between the foregoing, etc.). However, in other embodiments, the proximal electrode portion 30B is greater than 4mm (e.g., 4-5, 5-6, 6-7, 7-8, 8-9, 9-10mm, greater than 10mm, etc.) or less than 1mm (e.g., 0.1-0.5, 0.5-1, 1-1.5, 1.5-2mm, lengths between the foregoing ranges, etc.), as desired or required. In embodiments where the high resolution electrodes or portions are positioned on the catheter shaft, the length of the electrodes may be 1 to 5mm (e.g., 1-2, 2-3, 3-4, 4-5mm, lengths in between, etc.). However, in other embodiments, the electrodes or electrode portions may be longer than 5mm (e.g., 5-6, 6-7, 7-8, 8-9, 9-10, 10-15, 15-20mm, lengths in between the foregoing, lengths greater than 20mm, etc.), as desired or required.

According to several embodiments, the use of a high resolution combined electrode or composite tip (e.g., a split tip) design may allow a user to simultaneously ablate or otherwise thermally treat a target tissue and map (e.g., using high resolution mapping) in a single configuration. Thus, such a system may advantageously allow for accurate high resolution mapping during a procedure (e.g., to confirm that a desired level of treatment is occurring). In some embodiments, a high resolution tip design comprising two electrodes or electrode portions 30A, 30B may be used to record high resolution bipolar electrograms. For this purpose, two electrodes or electrode portions 30A, 30B may be connected to the inputs of the EP recorder. In some embodiments, the relatively small separation distance (e.g., gap G) between the electrodes or electrode portions 30A, 30B enables high resolution mapping.

In some embodiments, the medical device (e.g., catheter) 20 may include three or more electrodes or electrode portions (e.g., separated by gaps), as desired or required. Additional details regarding such arrangements are provided below. According to some embodiments, regardless of how many electrodes or electrode portions are positioned along the catheter tip, the electrodes or electrode portions 30A, 30B are radiofrequency electrodes and comprise one or more metals such as, for example, stainless steel, platinum-iridium, gold-plated alloys, and the like.

According to some embodiments, as shown in fig. 2, the electrodes or electrode portions 30A, 30B are spaced apart (e.g., longitudinally or axially) from one another using a gap (e.g., an electrically insulating gap). In some embodiments, the length of the gap G (or the separation distance between adjacent electrodes or electrode portions) is 0.5 mm. In other embodiments, the gap G or separation distance is greater than or less than 0.5mm, such as, for example, 0.1-1mm (e.g., 0.1-0.2, 0.2-0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6, 0.6-0.7, 0.7-0.8, 0.8-0.9, 0.9-1.0mm, values between the foregoing ranges, less than 0.1mm, greater than 1mm, etc.), as desired or required.

According to some embodiments, as depicted in fig. 2, the separators 34 are positioned within the gap G between adjacent electrodes or electrode portions 30A, 30B. The separator may comprise one or more electrically insulating materials such as, for example, Teflon (Teflon), Polyetheretherketone (PEEK), polyetherimide resins (e.g., ultem (tm)), diamond (e.g., industrial grade diamond), ceramic materials, polyimide, and the like.

As described above with respect to the gap G separating adjacent electrodes or electrode portions, the length of the insulating separator 34 may be 0.5 mm. In other embodiments, the length of the separator 34 can be greater than or less than 0.5mm (e.g., 0.1-0.2, 0.2-0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6, 0.6-0.7, 0.7-0.8, 0.8-0.9, 0.9-1.0mm, values between the foregoing ranges, less than 0.1mm, greater than 1mm, etc.), as desired or required.

According to some embodiments, as discussed in more detail herein, to successfully ablate or otherwise successfully heat or treat target tissue of a subject with a high resolution tip electrode design (such as the one depicted in fig. 2), the two electrodes or electrode portions 30A, 30B are electrically coupled to one another at an RF treatment (e.g., ablation) frequency or range of RF treatment frequencies. Thus, two electrodes or electrode portions may advantageously act (e.g., behave) as a single longer electrode at RF treatment frequencies or treatment frequency ranges (e.g., frequencies between 400kHz and 600 kHz), while two electrodes or electrode portions behave as separate electrodes at frequencies used for mapping purposes (e.g., frequencies less than 1 kHz). For clarity, a filtering element such as discussed below may have such a value: such that at an ablation or other treatment frequency, the filtering element effectively shorts out the two electrodes or electrode portions, thereby causing the two electrodes or electrode portions to appear as a single compound tip electrode during ablation or treatment, and the filtering element effectively presents an open circuit between the two electrodes or electrode portions such that they appear as electrically separate, distinct electrodes for mapping purposes (e.g., EGM mapping or recording). As shown, one of the electrode portions 30A (e.g., the distal electrode) can be electrically coupled to an energy delivery module 40 (e.g., an RF generator). As discussed herein, module 40 may include one or more components or features such as, for example, an energy generation device configured to selectively energize and/or otherwise activate energy members (e.g., RF electrodes), one or more input/output devices or components, a processor (e.g., a processing or control device) configured to adjust one or more aspects of the therapy system, memory, or the like.

Fig. 3 and 4 illustrate different embodiments of catheter systems 100, 200 incorporating high resolution tip designs. For example, in fig. 3, an electrode (e.g., a radio frequency electrode) along a distal end of the electrode includes a first or distal electrode or electrode portion 110 and a second or proximal electrode or electrode portion 114. As shown and discussed in greater detail herein with respect to other configurations, the high resolution tip design 100 includes a gap G between the first and second electrodes or electrode portions 110, 114. In some configurations, the second or proximal electrode or electrode portion 114 is generally longer than the first or distal electrode or electrode portion 110. For example, the length of the proximal electrode 114 may be between 1 and 20 times the length of the distal electrode 110 (1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-16, 16-17, 17-18, 18-19, 19-20, values between the aforementioned ranges, etc.), as desired or required. In other embodiments, the length of the proximal electrode may be greater than 20 times (e.g., 20-25, 25-30, greater than 30 times, etc.) the length of the distal electrode. In still other embodiments, the distal electrode and the proximal electrode are about the same length. However, in some embodiments, distal electrode 110 is longer (e.g., 1 to 20 times longer, such as, for example, 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-16, 16-17, 17-18, 18-19, 19-20, values between the aforementioned ranges, etc.) than proximal electrode 114.

As shown in fig. 3 and noted above, regardless of their exact design, relative length diameters, orientations, and/or other characteristics, the electrodes or electrode portions 110, 114 may be separated by a gap G. The gap G may comprise a relatively small electrically insulating gap or space. In some embodiments, the electrically insulating separator 118 may be positioned closely between the first and second electrodes or electrode portions 110, 114. In certain embodiments, the divider 118 may have a length of about 0.5 mm. However, in other embodiments, the length of the separator 118 can be greater than or less than 0.5mm (e.g., 0.1-0.2, 0.2-0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6, 0.6-0.7, 0.7-0.8, 0.8-0.9, 0.9-1.0mm, values between the foregoing ranges, less than 0.1mm, greater than 1mm, etc.), as desired or required. The spacers may comprise one or more electrically insulating materials (e.g., materials having a conductivity less than about 1000 or less than that of a metal or alloy (e.g., 500-. The separator may comprise one or more electrically insulating materials, for example, teflon, Polyetheretherketone (PEEK), polyoxymethylene, acetal resin or polymers, or the like.

As shown in fig. 3, the separator 118 may be cylindrical in shape and may have the same or similar diameter and configuration as the adjacent electrodes or electrode portions 110, 114. Thus, in some embodiments, the outer surface formed by electrodes or electrode portions 110, 114 and separator 118 may be substantially uniform or smooth. However, in other embodiments, the shape, size (e.g., diameter), and/or other characteristics of the separator 118 may be different from one or more of the adjacent electrodes or electrode portions 110, 114, as desired or required for a particular application or use.

Fig. 4 illustrates an embodiment of a system 200 having three or more electrodes or electrode portions 210, 212, 214, the electrodes or electrode portions 210, 212, 214 separated by respective gaps G1, G2. The use of such additional gaps, and thus additional electrodes or electrode portions 210, 212, 214 that are physically separated (e.g., by gaps) but in close proximity to one another, may provide additional benefits to the high resolution mapping capabilities of the system. For example, the use of two (or more) gaps may provide more accurate high-resolution mapping data related to the tissue being treated. Such multiple gaps may provide information about the directionality of cardiac signal propagation. In addition, high-resolution mapping with high-resolution electrode portions involving multiple gaps may provide a more expanded view of lesion progression during an ablation procedure, as well as higher confidence that no living tissue strands are left within a target treatment volume. In some embodiments, a high resolution electrode having a plurality of gaps may optimize the ratio of mapped tissue surface to ablated tissue surface. Preferably, the ratio is in the range of 0.2 to 0.8 (e.g., 0.2-0.3, 0.3-0.4, 0.4-.5, 0.5-0.6, 0.6-0.7, 0.7-0.8, ratios between the foregoing, etc.). Although fig. 4 shows an embodiment with a total of three electrodes or electrode portions 210, 212, 214 (and thus two gaps G1, G2), the system may be designed or otherwise modified to include additional electrodes or electrode portions, and thus additional gaps. For example, in some embodiments, an ablation or other treatment system may include 4 or more (e.g., 5, 6, 7, 8, more than 8, etc.) electrodes or electrode portions (and thus, 3 or more gaps, e.g., 3, 4, 5, 6, 7 gaps, more than 7 gaps, etc.), as desired or required. In such a configuration, gaps (and/or electrical separators 218a, 218b) may be positioned between adjacent electrodes or electrode portions according to the embodiments shown in fig. 2-4.

As depicted in fig. 3 and 4, the irrigation tubes 120, 220 may be routed (route) within the interior of the catheter (not shown for clarity). In some embodiments, the irrigation tube 120, 220 may extend from a proximal portion of the catheter (e.g., where the irrigation tube 120, 220 may be placed in fluid communication with a fluid pump) to a distal end of the system. For example, in some arrangements, as shown in the side views of fig. 3 and 4, the irrigation tube 120, 220 extends and is in fluid communication with one or more fluid ports 211, the one or more fluid ports 211 extending radially outward through the distal electrode 110, 210. Thus, in some embodiments, the treatment system includes an open-flush design in which saline and/or other fluids are selectively delivered through the catheter (e.g., within the fluid tube 120, 220) and radially outward through the one or more outlet ports 111, 211 of the electrodes 110, 210. Delivery of such saline or other fluid may assist in removing heat away from the electrodes and/or the tissue being treated. In some embodiments, such an open irrigation system may help prevent overheating of the target tissue, particularly tissue contacted along the electrodes. An open flush design is incorporated into the system shown schematically in fig. 2. For example, as depicted in fig. 2, the distal electrode or electrode portion 34 may include a plurality of outlet ports 36 through which saline or other irrigation fluid may exit.

According to some embodiments, the catheter may include a high resolution tip electrode design that includes one or more gaps in a circumferential direction (e.g., radial) in addition to or instead of the longitudinal direction. One embodiment of a system 300 including one or more electrodes 310A, 310B is shown in fig. 5. As shown, in an arrangement including two or more electrodes, the electrodes 310A, 310B may be longitudinally or axially offset from one another. For example, in some embodiments, the electrodes 310A, 310B are positioned along or near the distal end of the catheter. In some embodiments, the electrodes 310A, 310B are positioned along an exterior portion of a catheter or other medical device. However, in other configurations, one or more of the electrodes may be positioned along different portions of the catheter or other medical instrument (e.g., along at least an interior portion of the catheter), as desired or required.

With continued reference to fig. 5, each electrode 310A, 310B may include two or more portions 320A, 322A and/or 320B, 322B. As shown, in some embodiments, each portion 320A, 322A and/or 320B, 322B may extend half way (e.g., 180 degrees) around the diameter of the catheter. However, in other embodiments, the circumferential extent of each portion may be less than 180 degrees. For example, each portion may extend between 0 and 180 degrees (e.g., 15, 30, 45, 60, 75, 90, 105, 120 degrees, degrees in between the foregoing, etc.) around the circumference of the conduit along which it is mounted. Thus, in some embodiments, the electrode may comprise 2, 3, 4, 5, 6 or more circumferential portions, as desired or required.

According to various embodiments disclosed herein, regardless of the design and orientation of the circumferential electrode portions, an electrical insulation gap G may be provided between adjacent portions to facilitate the ability to use the electrodes for high resolution mapping. Further, as shown in the embodiment of fig. 5, two or more (e.g., 3, 4, 5, more than 5, etc.) electrodes 310A, 310B having two or more circumferential or radial portions may be included in a particular system 300, as desired or required.

In alternative embodiments, the various embodiments of the high resolution tip designs disclosed herein, or variations thereof, may be used with non-irrigation systems or closed irrigation systems (e.g., systems that circulate saline and/or other fluids through or within one or more electrodes to selectively remove heat therefrom). Thus, in some arrangements, the conduit may comprise two or more irrigation tubes or pipes. For example, one tube or other conduit may be used to deliver fluid to or near the electrode, while a second tube or other conduit may be used to return fluid through the catheter in the opposite direction.

According to some embodiments, the high resolution tip electrode is designed to balance the current load between individual electrodes or electrode portions. For example, if the therapy system is not carefully configured, the electrical load may be delivered primarily to one or more of the electrodes or electrode portions of the high resolution tip system (e.g., a shorter or smaller distal electrode or electrode portion). This can lead to undesirable uneven heating of the electrodes and, therefore, uneven heating (e.g., ablation) of adjacent tissue of the subject. Thus, in some embodiments, one or more load balancing configurations may be used to help ensure that heating along various electrodes or electrode portions of the system will generally be balanced. As a result, a high resolution tip design may advantageously function like a longer single electrode as compared to two or more electrodes receiving unequal electrical loads (and thus delivering unequal heat or therapeutic levels to the target tissue of the subject).

One embodiment of a configuration that may be used to balance the current load delivered to each of the electrodes or electrode portions in a high resolution tip design is schematically illustrated in FIG. 6. As shown, one of the electrodes (e.g., distal electrode) 30A may be electrically coupled to an energy delivery module 40 (e.g., RF generator). As discussed herein, module 40 may include one or more components or features such as, for example, an energy generation device configured to selectively energize and/or otherwise activate energy members (e.g., RF electrodes), one or more input/output devices or components, a processor (e.g., a processing or control unit) configured to adjust one or more aspects of the therapy system, memory, or the like. Further, such modules may be configured to operate manually or automatically, as desired or required.

In the embodiment schematically depicted in fig. 6, the distal electrode 30A is energized using one or more conductors 82 (e.g., wires, cables, etc.). For example, in some arrangements, the exterior of the irrigation tube 38 includes and/or is otherwise coated with one or more electrically conductive materials (e.g., copper, other metals, etc.). Thus, as shown in fig. 6, one or more conductors 82 may be placed in contact with such electrically conductive surfaces or portions of the irrigation tube 38 to electrically couple the electrode or electrode portion 30A to an energy delivery module (e.g., energy delivery module 40 of fig. 1). However, one or more other devices and/or methods of placing the electrode or electrode portion 30A in electrical communication with the energy delivery module may be used. For example, one or more wires, cables, and/or other conductors may be coupled directly or indirectly to the electrodes without the use of irrigation tubing.

With continued reference to fig. 6, one or more band pass filtering elements 84, such as capacitors, filtering circuits (see, e.g., fig. 16), and the like, may be used to electrically couple the first or distal electrode or electrode portion 30A to the second or proximal electrode or electrode portion 30B. For example, in some embodiments, the band pass filtering element 84 comprises a capacitor that electrically couples the two electrodes or electrode portions 30A, 30B when a radio frequency current (e.g., a radio frequency current or power having a frequency suitable for ablation or other treatment of tissue) is applied to the system. In one embodiment, the capacitor 84 comprises a 100nF capacitor that introduces a series impedance below about 3 Ω at 500kHz, which 500kHz is the target frequency for RF ablation, according to some arrangements. However, in other embodiments, the capacitance of the capacitor(s) or other band pass filtering element 84 incorporated into the system may be greater than or less than 100nF (e.g., 5nF to 300nF), depending on the operating RF frequency, as desired or required. In some embodiments, the capacitance of the filtering element 84 is selected based on a target impedance at a particular frequency or range of frequencies. For example, in some embodiments, the system may be operated at a frequency of 200kHz to 10MHz (e.g., 200-. Thus, the capacitor coupling adjacent electrodes or electrode portions to each other may be selected based on a target impedance for a particular frequency. For example, a 100nF capacitor provides a coupling impedance of about 3 Ω at an operating ablation frequency of 500 kHz.

In some embodiments, a 3 Ω series impedance across the electrodes or electrode portions 30A, 30B is sufficiently low so as to not adversely affect the resulting tissue heating profile when the system is in use, when compared to the impedance of the conductor 82 (e.g., wire, cable, etc.), which may be about 5-10 Ω, and the impedance of the tissue, which may be about 100 Ω. Thus, in some embodiments, the filtering element is selected such that the series impedance across the electrode or electrode portion is lower than the impedance of the conductor that supplies the RF energy to the electrode. For example, in some embodiments, the insertion impedance of the filtering element is 50% or less of the impedance of the conductor 82, or 10% or less of the equivalent tissue impedance.

In some embodiments, filtering elements (e.g., capacitors, filtering circuits, such as those described herein with reference to fig. 16, etc.) may be located at various locations of the device or companion system. For example, in some embodiments, the filtering element is located on or within the catheter (e.g., near the distal end of the catheter, near the electrodes, etc.). However, in other embodiments, the filtering element is separate from the catheter. For example, the filtering element may be positioned within or along a handle to which the catheter is secured, within a generator or other energy delivery module, within a separate processor or other computing device or component, and/or the like.

Similarly, referring to the schematic of fig. 7, a filtering element 384 may be included in the electrode 310, the electrode 310 including the circumferentially arranged portions 320, 322. In fig. 7, the filtering element 384 allows the entire electrode 310 to be excited in the RF frequency range (e.g., when the electrode is activated for ablation). One or more RF wires or other conductors 344 may be used to deliver power from a generator or source to the electrodes. In addition, separate conductors 340 may be used to electrically couple the electrodes 310 for mapping purposes.

In embodiments where the high resolution tip design (e.g., fig. 4) includes three or more electrodes or electrode portions, additional filtering elements (e.g., capacitors) may be used to electrically couple the electrodes or electrode portions to one another. Such capacitors or other filtering elements may be selected to create a heating profile that is generally uniform along the entire length of the high-resolution tip electrode. As noted in more detail herein, for any of the embodiments disclosed herein or variations thereof, the filtering element may include something other than a capacitor. For example, in some arrangements, the filtering element includes an LC circuit (e.g., a resonant circuit, an oscillating circuit, a tuning circuit, etc.). Such embodiments may be configured to allow simultaneous application of RF energy and measurement of EGM recordings.

As discussed above, the relatively small gap G between adjacent electrodes or electrode portions 30A, 30B may be used to facilitate high-resolution mapping of the target tissue. For example, with continued reference to the schematic diagram of FIG. 6, separate electrodes or electrode portions 30A, 30B may be used to generate an electrogram that accurately reflects the local electrical potentials of the tissue being treated. Thus, a physician or other practitioner using the treatment system can more accurately detect the effect of energy delivery to the target tissue before, during, and/or after the procedure. For example, the more accurate electrogram data produced by such a configuration may enable a physician to detect any gaps or portions of the target anatomical region that are not properly ablated or otherwise treated. In particular, the use of a high resolution tip design may enable a cardiac electrophysiologist to more accurately assess the morphology of the resulting electrogram, its amplitude and width, and/or determine a pacing threshold. In some embodiments, morphology, amplitude, and pacing thresholds are accepted, and reliable EP markers provide useful information about the outcome of ablation or other thermal treatment processes.

According to some arrangements, the high resolution tip electrode embodiments disclosed herein are configured to provide local high resolution electrograms. For example, an electrogram obtained using high resolution tip electrodes according to embodiments disclosed herein may provide electrogram data (e.g., graphical output) 400a, 400b, as shown in fig. 8. As depicted in fig. 8, the local electrograms 400a, 400b generated using the high resolution tip electrode embodiments disclosed herein include amplitudes a1, a 2.

With continued reference to fig. 8, the amplitudes of the electrograms 400a, 400b obtained using the high resolution tip electrode system may be used to determine whether the target tissue in the vicinity of the high resolution tip electrode has been sufficiently ablated or otherwise treated. For example, according to some embodiments, the amplitude a1 of the electrogram 400a in untreated tissue (e.g., tissue that has not been ablated or otherwise heated) is greater than the amplitude a2 of the electrogram 400b that has been ablated or otherwise treated. Thus, in some embodiments, the amplitude of the electrogram may be measured to determine whether tissue has been treated. For example, the electrogram amplitude a1 of untreated tissue in the subject may be recorded and used as a baseline. Future electrogram amplitude measurements may be obtained and compared to the baseline amplitude in an attempt to determine whether tissue has been ablated or otherwise treated to a sufficient or desired degree.

In some embodiments, a comparison is made between the baseline amplitude (a1) relative to the electrogram amplitude (a2) at the tissue location being tested or evaluated. The ratio of a1 to a2 can be used to provide a quantitative measure for assessing the likelihood that ablation has been completed. In some arrangements, if the ratio (i.e., a1/a2) is above some minimum threshold, the user may be informed that the tissue that obtained the a2 amplitude has been properly ablated. For example, in some embodiments, sufficient ablation or treatment may be confirmed when the a1/a2 ratio is greater than 1.5 (e.g., 1.5-1.6, 1.6-1.7, 1.7-1.8, 1.8-1.9, 1.9-2.0, 2.0-2.5, 2.5-3.0, values in between the foregoing, greater than 3, etc.). However, in other embodiments, confirmation of ablation may be obtained when the ratio of A1/A2 is less than 1.5 (e.g., 1-1.1, 1.1-1.2, 1.2-1.3, 1.3-1.4, 1.4-1.5, values in between the foregoing).

For any of the embodiments disclosed herein, a catheter or other minimally invasive medical device may be delivered to a target anatomical location (e.g., an atrium, pulmonary vein, other cardiac location, renal artery, other vessel or lumen, etc.) of a subject using one or more imaging techniques. Accordingly, any of the ablation systems disclosed herein may be configured for use with (e.g., separate from or at least partially integrated with) an imaging device or system, such as, for example, fluoroscopy techniques, intracardiac echocardiography (ICE) techniques, etc.

Thermal shunt

Fig. 9 illustrates one embodiment of a system 1100 that includes an electrode 1130 (e.g., a unitary RF electrode, a composite (e.g., split tip) electrode having two, three, or more portions, other types of electrodes, etc.) located at or near the distal end of a catheter 1120. . Additionally, as with any other embodiments disclosed herein, the system can further include a plurality of ring electrodes 1170 to assist in performing a treatment procedure (e.g., mapping of tissue near a treatment site, monitoring of a subject, etc.). Although embodiments of the various systems and related methods disclosed herein are described in the context of radio frequency-based ablation, heat transfer concepts (including thermal shunt embodiments) (alone or in combination with other embodiments described herein (e.g., compound electrode concepts, temperature sensing concepts, etc.) may also be implemented in other types of ablation systems, such as, for example, those systems that use microwave emitters, ultrasound transducers, cryoablation members, and/or the like to target tissue of a subject.

Referring to the corresponding partial exposure views of the distal end of the catheter shown in fig. 9 and 10, one or more heat transfer members or other heat transfer components or features (including any of the thermal shunt embodiments disclosed herein) may be used to facilitate heat transfer from the electrode or the vicinity of the electrode to the irrigation conduit 1108 extending through the interior of the catheter 1120. For example, in some embodiments, as depicted in fig. 10, one or more heat transfer disks or members 1140, 1142 (e.g., heat spreader disks or members) may be positioned along the length of the electrode 1130. In some arrangements, the disks or other heat transfer members 1140, 1142 (including any of the thermal shunt embodiments disclosed herein) comprise separate components that may or may not be in contact with each other. However, in other embodiments, the heat transfer disks or other heat transfer members 1140, 1142 comprise a unitary or monolithic structure, as desired or required. The disks 1140, 1142 may be in direct or indirect thermal communication with the irrigation conduit 1108, the irrigation conduit 1108 passing at least partially through an interior portion of the catheter (e.g., along a longitudinal centerline). For example, the disks 1140, 1142 may extend to and contact the outer surface of the irrigation pipe and/or another interior portion of the catheter (e.g., for non-irrigation components or portions of embodiments that do not include active cooling using open or closed irrigation). However, in other embodiments, as shown in fig. 11, the disks 1140, 1142 may be in thermal communication (e.g., directly via contact or indirectly) with one or more other heat exchange components or members (including any thermal shunt components or members) located between the disks and the flush tube.

The heat sink includes both: (i) heat retention transferors (in which heat is confined to/retained by a component); and (ii) a thermal shunt (which may also be referred to as a heat transfer member) for shunting or transferring heat from, for example, the electrode to the flushing channel. In one embodiment, a heat retention sink (heat retention sink) is used to retain heat for a period of time. Preferably, a heat diverter (heat transfer member) is used instead of a heat retainer. In some embodiments, a thermal shunt (heat transfer member) provides more efficient dissipation of heat and improved cooling, thus providing protection to, for example, tissue that is considered non-target tissue. For any of the embodiments disclosed herein, one or more thermal shunt components may be used to efficiently and safely transfer heat away from the electrode and/or the heated tissue. In some embodiments, the device or system may be configured to adequately transfer heat away from the electrode without any additional components or features (e.g., using only the thermal shunt configuration disclosed herein).

In any of the embodiments disclosed herein, the ablation system can include one or more irrigation conduits extending at least partially along (e.g., through an interior portion of) a catheter or other medical device configured for placement within a subject. The irrigation conduit(s) may be part of an open irrigation system in which fluid is withdrawn through one or more exit ports or openings along the distal end of the catheter (e.g., at or near the electrodes) to cool the electrodes and/or adjacent target tissue. However, alternatively, the irrigation conduit(s) may be part of a closed irrigation system in which irrigation fluid is at least partially circulated through the catheter (e.g., as opposed to being expelled from the catheter) (e.g., in the vicinity of the electrode or other ablation member to selectively cool the electrode and/or adjacent tissue of the subject). For example, in some arrangements, the catheter includes at least two internal fluid conduits (e.g., a delivery conduit and a return conduit) to circulate the flush fluid to the distal end of the catheter and to effect a desired or necessary heat transfer with the distal end of the catheter, as desired or required. Further, in some embodiments, to facilitate heat transfer between heat transfer members or components (e.g., thermal shunt members or components) included in the ablation system, the system may include an irrigation conduit comprising one or more metals and/or other good heat transfer materials (e.g., copper, stainless steel, other metals or alloys, ceramics, polymers, and/or other materials having relatively good heat transfer properties, etc.). In still other embodiments, the catheter or other medical device of the ablation system does not include any active fluid cooling system (e.g., open or closed irrigation channels or other components extending therethrough), as desired or required. As discussed in more detail herein, such embodiments that do not include the use of active cooling through the fluid passage of the catheter may advantageously dissipate and/or dissipate heat away from the electrode(s) and/or tissue being treated with enhanced heat transfer components and/or designs.

In some embodiments, the irrigation conduit is in fluid communication only with an exit port located along the distal end of the elongate body. In some embodiments, the catheter includes only irrigation exit openings along the distal end of the catheter (e.g., along the distal end or the electrodes). In some embodiments, the system does not include any flushing openings along the heat transfer member (e.g., thermal shunt member), and/or, as discussed herein, the system does not include an active flushing system at all. Thus, in such embodiments, the use of a heat transfer member along the catheter (e.g., at or near the electrode or other ablation member) helps to more evenly distribute heat generated by the electrode or other ablation member and/or to aid in heat transfer with the surrounding environment (e.g., blood or other fluid traveling along the exterior of the ablation member and/or catheter).

With continued reference to fig. 10, the proximal end 1132 of the electrode 1130 includes one or more additional heat transfer members 1150, the one or more additional heat transfer members 1150 including any of the thermal shunt embodiments disclosed herein. For example, according to some embodiments, such additional heat transfer members 1150 (e.g., thermal shunt members) include one or more fins (fin), pins, and/or other members in thermal communication with the flush tube 108 extending through the interior of the conduit of the system. Thus, with the thermal transfer disks or other thermal transfer members 1140 (including thermal shunt members) positioned along the length of the electrodes 1130, when the electrodes are activated, heat can be transferred via these thermal transfer members 1150 and thus removed from the electrodes, adjacent portions of the catheter, and/or adjacent tissue of the subject.

In any of the embodiments disclosed herein, or variations thereof, the heat transfer members 1140, 1150 of the system 1100 placed in thermal communication with the flushing conduit 1108 can comprise one or more materials that include good heat transfer properties, including but not limited to good heat diverting properties. For example, in some embodiments, the thermal conductivity of the material(s) included in the heat transfer member and/or the entire heat transfer assembly (e.g., when considered as a unitary member or structure) is greater than 300W/m/deg.C (e.g., 300-. Possible materials with good thermal conductivity properties include, but are not limited to, copper, brass, beryllium, other metals and/or alloys, alumina, ceramics, other ceramics, industrial diamond (e.g., chemical vapor deposition industrial diamond), and/or other metallic and/or non-metallic materials.

According to certain embodiments in which the heat transfer member comprises a thermal shunt member, the thermal diffusivity of the material(s) included in the thermal shunt member and/or the entire shunt assembly (e.g., when considered as a unitary member or structure) is greater than 1.5cm²Per second (e.g., 1.5-2, 2-2.5, 2.5-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-20 cm)²A value between the aforementioned ranges, greater than 20cm²In seconds). Thermal diffusivity measures the ability of a material to conduct thermal energy relative to its ability to store thermal energy. Thus, even though a material may transfer heat efficiently (e.g., may have a relatively high thermal conductivity), it may not have good thermal diffusion properties due to its thermal storage properties. Unlike heat transfer, thermal shunting requires the use of materials that have high thermal conductivity properties (e.g., rapid transfer of heat through a mass or volume) and low thermal capacity (e.g., do not store heat). Possible materials with good thermal diffusivity and therefore good thermal shunting propertiesIncluding but not limited to industrial diamond (e.g., chemical vapor deposition industrial diamond), graphene, silica, other carbon-based materials, and/or the like.

The use of materials with good thermal diffusion properties may help ensure that heat may be efficiently transferred away from the electrodes and/or adjacent tissue during the course of treatment. Conversely, materials that have good thermal conductivity properties but do not have good thermal diffusion properties (such as, for example, copper, other metals or alloys, thermally conductive polypropylene or other polymers, etc.) will tend to retain heat. As a result, the use of such heat-storing materials may result in the temperature along the electrode and/or the tissue being treated being maintained at an undesirably elevated level (e.g., in excess of 75 degrees celsius), especially during relatively long ablation procedures, which may lead to charring, thrombosis, and/or other heat-related problems.

Industrial diamonds (e.g., chemical vapor deposition industrial diamonds) and other materials with the requisite thermal diffusion properties for use in thermal shunt networks include good thermal conduction characteristics, as disclosed in various embodiments herein. This good thermal conduction aspect results from the relatively high thermal conduction value (k) and the way in which the thermal shunt members of the network are arranged relative to each other and to the tissue within the tip. For example, in some embodiments, when RF energy is emitted from the tip and ohmic heating within the tissue generates heat, the exposed distal-most shunt member (e.g., 0.5mm from the distal-most side of the tip) can actively extract heat from the injury site. Thermal energy may advantageously be transferred through the shunt network in a relatively fast manner and dissipated through the shunt residing below the RF electrode surface, the thermal shunt network, through the proximal shunt member, and/or into the ambient environment. Heat shunted by the inner shunt member can be quickly transferred to an irrigation conduit extending through the interior of a catheter or other medical device. In other embodiments, heat generated by the ablation process may be shunted by both proximal and distal shunt members (e.g., shunt members exposed to the exterior of a catheter or other medical device, such as shown in many embodiments herein).

Further, as described above, a material having good heat diffusion properties for a thermal shunt network has not only necessary thermal conductivity properties but also a sufficiently low heat capacity value (c). This helps to ensure rapid dissipation of thermal energy from the tip to tissue interface and hot spots on the electrode without retaining heat in the thermal shunt network. Thermal conduction constitutes the primary heat dissipation mechanism that ensures rapid and efficient cooling of the tissue surface and the RF electrode surface. Conversely, heat transfer (e.g., having relatively high thermal conductivity characteristics but also having relatively high heat capacity characteristics) will store thermal energy. During long ablation procedures, this stored heat may exceed 75 degrees celsius. In this case, thrombus and/or char formation may undesirably occur.

The heat convection aspect of the various embodiments disclosed herein is twofold. First, the flush lumen of the catheter may absorb thermal energy transferred to it through the shunt network. Such thermal energy may then be flushed away from the distal end of the RF tip via the flush port. However, in a closed irrigation system, this thermal energy may be transferred back to the proximal end of the catheter where it may be removed. Second, the exposed shunt surface along the exterior of the catheter or other medical device may further assist in dissipating heat from the electrode and/or tissue being treated. Such heat dissipation may be achieved, for example, via the inherent convective cooling aspects of blood flowing over the surface of the electrodes.

Thus, the use of a material with good heat spreading properties, such as an industrial diamond (e.g., chemical vapor deposition industrial diamond), in the thermal shunt network may help ensure that heat is quickly and efficiently transferred away from the electrode and the treated tissue while maintaining the thermal shunt network cool (e.g., due to its low thermal capacity properties). This may create a safer ablation catheter and associated treatment method, as potentially dangerous heat is not introduced into the procedure via the thermal shunt network itself.

For example, in some embodiments, the temperature of the electrode is about 60 degrees celsius during the course of an ablation procedure that attempts to maintain the tissue of the subject at a desired temperature of about 60 degrees celsius. Further, the temperature of a conventional heat transfer member (e.g., copper, other metal or alloy, thermally conductive polymer, etc.) located near the electrodes is about 70 to 75 degrees celsius during this process. Conversely, the temperature of various portions or components of the thermal shunt network of the systems disclosed herein may be approximately 60 to 62 degrees celsius (e.g., 10% to 30% lower than a comparable thermally conductive system) for the same desired level of tissue treatment.

In some embodiments, the thermal shunt members disclosed herein draw heat from the ablated tissue and shunt it into the irrigation channel. Similarly, heat is extracted from potential hot spots formed at the edges of the RF electrode and shunted into the irrigation channel through a thermal shunt network. Heat can be advantageously released from the irrigation channel into the blood stream via convective cooling and dissipated. In a closed irrigation system, heat can be removed from the system without draining irrigation fluid into the subject.

According to some embodiments, various thermal shunt systems disclosed herein rely on heat conduction as the primary cooling mechanism. Accordingly, such embodiments do not require that a substantial portion of the thermal shunt network extend to the outer surface of the catheter or other medical device (e.g., for direct exposure to the blood stream). Indeed, in some embodiments, the entire shunt network may reside inside the catheter tip (i.e., where no portion of the thermal shunt network extends outside of the catheter or other medical instrument). Further, various embodiments disclosed herein do not require electrical isolation of the thermal shunt from the RF electrode or the irrigation channel.

According to some embodiments, the heat transfer disks and/or other heat transfer members 1140, 1150, 1250A (including thermal shunt members or components) included in a particular system may extend continuously and/or intermittently or partially to the flush tube 108, as desired or required for a particular design or configuration. For example, as shown in the embodiment of fig. 10, the proximal heat transfer member 1150 (e.g., thermal shunt member) can include one or more (e.g., 2, 3, 4, 5, more than 5, etc.) wings or portions 1154, 1254 extending radially outward from the base or inner member 1152, 1252. In some embodiments, such fins or radially extending portions 1154, 1254 are equally spaced from one another to more evenly transfer heat toward the flush conduit 1108 with which the heat transfer member 1150, 1250A is in thermal communication. However, alternatively, the heat transfer members 1150, 1250A, including but not limited to thermal shunt members, may comprise a substantially solid or continuous structure between the flush tube 1108 and the radially outer portion or region of the conduit.

According to some embodiments, the heat transfer member (e.g., fins) 1150 may extend proximally to a proximal end of the electrode(s) included along the distal end of the catheter. For example, as shown in fig. 10, the heat transfer member 1150 (e.g., thermal shunt member) may extend to the proximal end of the electrode 1130, near the proximal end of the electrode 1130, or beyond the proximal end of the electrode 1130. In some embodiments, the heat transfer member 1150 terminates at or near the proximal end 1132 of the electrode 1130. However, in other arrangements, the heat transfer member 1150 (including, but not limited to, a thermal shunt member) extends beyond the proximal end 1132 of the electrode 1130, and in some embodiments, the heat transfer member 1150 is in contact with and/or otherwise in direct or indirect thermal communication with a distally located heat transfer member comprising the thermal shunt member (e.g., a heat transfer disk or other heat transfer member located along or near the length of the electrode 1130), as desired or required. In other embodiments, the proximal heat transfer member (e.g., thermal shunt member) terminates proximally at the proximal end 1132 of the electrode or other ablation member.

In any of the embodiments disclosed herein, including the systems discussed in connection with fig. 9-12 that include enhanced heat transfer (e.g., thermal shunting) properties, the systems may include one or more temperature sensors or temperature detection components (e.g., thermocouples) for detection of tissue temperature at a depth. For example, in the embodiments shown in fig. 9 and 10, the electrodes and/or other portions of the distal end of the catheter may include one or more sensors (e.g., thermocouples, thermistors, etc.) and/or the like. Accordingly, signals received by the sensors and/or other temperature measurement components may be advantageously used to determine or approximately determine the extent to which the target tissue is being treated (e.g., heated, cooled, etc.). The temperature measurements may be used to control the ablation process (e.g., adjust power to the ablation member, terminate the ablation process, etc.) according to a desired or required protocol.

In some embodiments, the device further includes one or more temperature sensors or other temperature measurement devices to help determine the peak temperature (e.g., high or peak, low or valley, etc.) of the tissue being treated. In some embodiments, temperature sensors (e.g., thermocouples) located at, along, and/or near the ablation member (e.g., RF electrodes) can help determine whether contact is being made (and/or the degree to which such contact is being made) between the ablation member and the target tissue. In some embodiments, such peak temperatures may be determined without the use of a radiometer. Additional details regarding the use of temperature sensors (e.g., thermocouples) to determine peak tissue temperatures and/or to confirm or assess tissue contact are provided herein.

In some embodiments, for any of the systems disclosed herein (including but not limited to those shown herein) or variations thereof, one or more of the heat transfer members (including but not limited to a thermal shunt member) of the flush tube that facilitates heat transfer to the catheter are in direct contact with the electrode and/or the flush tube. However, in other embodiments, one or more of the heat transfer members (e.g., thermal shunt members) do not contact the electrodes and/or the flush tubes. Thus, in such embodiments, the heat transfer member is in thermal communication with the electrode and/or the irrigation conduit, but is not in physical contact with these components. For example, in some embodiments, one or more intermediate components, layers, coatings, and/or other members are positioned between a heat transfer member (e.g., a thermal shunt member) and an electrode (or other ablation member) and/or irrigation conduit.

Fig. 11 illustrates another embodiment of an ablation system 1200, the ablation system 1200 including an electrode (e.g., RF electrode, composite (e.g., split tip) electrode, etc.) or other ablation member 1230 positioned along or near the distal end of a catheter or other elongate member. In some embodiments, the inner portion 1236 of an electrode or other ablation member (not shown in fig. 11 for clarity) may include a separate inner heat transfer member 1250B, including any of the thermal shunt embodiments disclosed herein. Such a heat transfer member 1250B may supplement or replace any other heat transfer member located on, within, and/or near an electrode or other ablation member. For example, in the depicted embodiment, the system 1200 includes an internal heat transfer member 1250B and one or more disk-shaped or cylindrical heat transfer members 1240 (e.g., thermal shunt members) in the vicinity of the electrode 1230.

For any of the embodiments disclosed herein, at least a portion of the heat transfer member (including the thermal shunt member) in thermal communication with the irrigation conduit extends to the outer surface of the catheter adjacent to (and in some embodiments, in physical and/or thermal contact with) the electrode or other ablation member. Such a configuration may further enhance cooling of the electrode or other ablation member when the system is activated, particularly at or near the proximal end of the electrode or ablation member where heat may otherwise tend to be more concentrated (e.g., relative to other portions of the electrode or other ablation member). According to some embodiments, thermally conductive grease and/or any other thermally conductive material (e.g., thermally conductive liquid or other fluid, layer, member, coating, and/or portion) may be used to place a heat transfer (such as, for example, a thermal shunt member or thermal shunt network) in thermal communication with the flush tube, as desired or required. In such embodiments, such thermally conductive material places the electrode at least partially in thermal communication with the flush conduit.

With continued reference to fig. 11, a heat transfer member (e.g., a thermal shunt member) 1250B positioned along an interior portion of the electrode 1230 can include one or more fins, wings, pins, and/or other extension members 1254B. Such members 1254B may help enhance heat transfer with the flush tube 1208 (e.g., for a thermal shunt embodiment, thermal shunting to the flush tube 1208), may help reduce the overall size of the heat transfer member 1254B, and/or provide one or more additional advantages or benefits to the system 1200.

Another embodiment of an ablation system 1300 is shown in fig. 12, the ablation system 1300 including one or more heat transfer (e.g., thermal shunt) components or features 1350A, 1350B that facilitate overall heat transfer of an electrode or other ablation member during use. As shown, heat transfer (e.g., flow splitting) between one or more heat transfer members 1350B positioned along the interior of the electrode or other ablation member 1330 can be facilitated and otherwise enhanced by eliminating air gaps or other similar spaces between the electrode and the heat transfer members. For example, in the illustrated embodiment, one or more layers 1356 of electrically conductive material (e.g., platinum, gold, other metals or alloys, etc.) have been positioned between the interior of the electrode 1330 and the exterior of the heat transfer member 1350B. Such layer(s) 1356 may be applied continuously or intermittently between the electrode (or another type of ablation member or energy delivery member) and the adjacent heat transfer member(s), including but not limited to a thermal shunt member(s). Further, such layer(s) 1356 can be applied using one or more methods or processes, such as, for example, sputtering, other plating techniques, and/or the like. Such layer(s) 1356 may be used in any of the embodiments disclosed herein or variations thereof.

Fig. 13 illustrates a distal portion of a catheter or other medical device of an ablation system 1800, the ablation system 1800 including one or more heat transfer members 1850 (e.g., thermal shunt members), the one or more heat transfer members 1850 facilitating efficient transfer of heat generated by electrodes or other energy delivery members 1830. As shown in fig. 13, thermal shunt member 1850 is positioned proximate to (e.g., inside of) electrode 1830. Thus, as discussed in more detail herein, heat generated by the electrodes or other energy delivery members 1830 may be transferred via the one or more thermal shunt members 1850. As discussed above, the thermal shunt member advantageously comprises good thermal diffusion properties to transfer heat quickly without retaining heat. Thus, the likelihood of local hot spots (e.g., along the distal and/or proximal ends of the electrodes) may be prevented or reduced. In addition, heat dissipation or removal (e.g., away from the electrodes) may be more easily and/or faster achieved using the thermal shunt member 1850.

As discussed herein, for example, the thermal shunt member 1850 can comprise industrial diamond (e.g., chemical vapor deposition industrial diamond), graphene, silicon dioxide, or other carbon-based materials with good thermal diffusion properties, and/or the like. In some embodiments, the thermal shunt member 1850 comprises a combination of two, three, or more materials and/or portions, components, or members. In some embodiments, the thermal diffusivity of the material(s) included in the thermal shunt member and/or the entire thermal shunt network or assembly (e.g., when considered as a unitary member or structure) is greater than 1.5cm²Per second (e.g., 1.5-2, 2-2.5, 2.5-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-20 cm)²A value between the aforementioned ranges, greater than 20cm²In seconds).

The thermal shunt member 1850 (e.g., fins, rings, blocks, etc.) may be in direct or indirect contact with an electrode or other energy delivery member 1830. Regardless of whether direct physical contact is made between the electrode and one or more of the heat transfer shunts 1850, the heat shunt member 1850 may advantageously be in thermal communication with the electrode, thereby facilitating heat dissipation and/or heat transfer properties of the catheter or other medical device. In some embodiments, for example, one or more intermediate layers, coatings, members, and/or other components are positioned between the electrode (or other energy delivery member) and the thermal shunt member, as desired or required.

With continued reference to fig. 13, as discussed in other embodiments herein, the catheter or other medical device of the ablation system 1800 includes an open irrigation system configured to deliver a cooling fluid (e.g., saline) to and through the distal end of the catheter or other medical device. Such open irrigation systems may help remove heat from the electrodes or other energy delivery members during use. In some embodiments, the thermal shunt network and its good thermal spreading properties may help to quickly and efficiently transfer heat from the electrode and/or tissue being treated to the irrigation conduit or channel 1804 or lumen 1820 during use. For example, as depicted in fig. 13, the irrigation tube or channel 1804 extends through the interior of the catheter and is in fluid communication with one or more outlet ports 1811 along the distal member 1810 of the catheter. However, as discussed in more detail herein, the enhanced thermal shunt member may be incorporated into the design of a catheter or other medical instrument without the use of an open irrigation system and/or without an active fluid cooling system, as desired or required. In some embodiments, the flow of irrigation fluid (e.g., saline) through an irrigation tube or chamber of a catheter or other medical instrument may be modified to alter the thermal shunt occurring through the thermal shunt network. For example, in some embodiments, the flow rate of the flushing fluid through the catheter may be maintained below 5 ml/min (e.g., 1-2, 2-3, 3-4, 4-5 ml/min, flow rates between the aforementioned ranges, less than 1 ml/min, etc.) due to the good heat transfer properties of the thermal shunt network and its ability to retain no heat. In one embodiment, the flow rate of the irrigation fluid through the catheter is maintained at about 1 ml/min. In other embodiments, the flow rate of the irrigation fluid through the catheter may be between 5 and 15 milliliters per minute (e.g., 5-6, 6-7, 7-8, 8-9, 9-10, 11-12, 12-13, 13-14, 14-15 milliliters per minute, flow rates between the aforementioned rates, etc.) or greater than 15 milliliters per minute (e.g., 15-16, 16-17, 17-18, 18-19, 19-20 milliliters per minute, flow rates between the aforementioned rates, etc.), as desired or required. In some embodiments, this flush flow rate is significantly less than would otherwise be required in the following cases: if a non-thermal shunt member (e.g., metal, alloy, thermally conductive polymer, other conventional thermally conductive member, etc.) is being used to transfer heat away from the electrodes and/or tissue between treatments. For example, the required flow rate of irrigation fluid through the interior of a catheter with a thermal shunt member may be reduced by 20% to 90% (e.g., 20-25, 25-30, 30-35, 35-40, 40-45, 45-50, 50-55, 55-60, 60-65, 65-70, 70-75, 75-80, 80-85, 85-90%, percentages between the aforementioned ranges, etc.) when compared to systems using conventional heat transfer members or no heat transfer members at all (e.g., assuming the same heat is generated at the electrodes, the same anatomical location is being treated, and other parameters are the same). For example, in some commercially available RF ablation systems, a rinse flow rate of about 30 milliliters per minute (e.g., 25-35 milliliters per minute) is typically required to achieve a desired level of heat transfer from the electrode. As described above, in some arrangements, the systems disclosed herein that utilize thermal shunt networks can utilize a rinse flow rate of about 10 ml/min or less to effectively divert heat away from the electrodes. Thus, in such embodiments, the flush flow rate may be reduced by at least 60% to 70% relative to conventional and other commercially available systems.

Thus, as noted in more detail herein, the use of a thermal shunt material to shunt heat away from the electrode and/or adjacent tissue may also reduce the amount of irrigation fluid in the blood stream that is expelled to the subject in an open irrigation system. The use of thermal shunting in an ablation catheter may provide additional benefits to the ablation process since it is undesirable to drain irrigation fluid into the subject. For example, in some arrangements, draining excess saline or other cooling fluid to the heart, blood vessels, and/or other target areas of a subject can have negative physiological consequences to the subject (e.g., heart failure).

As described above, the use of thermal shunt components at or near the electrodes may also provide one or more additional benefits and advantages. For example, the use of thermal shunt components (e.g., as compared to conventional heat transfer components and members) requires significantly lower irrigation flow rates to effectively remove heat from the electrodes and surrounding tissue, and the irrigation fluid in such systems has little negative impact on any temperature sensors (e.g., sensor 1880 in fig. 13) located along or near the outside of the distal end of the catheter, allowing for more accurate temperature measurements. This is particularly important for systems such as the systems disclosed herein, in which the temperature sensor is configured to detect the temperature of adjacent tissue of the subject (e.g., the temperature of another component or portion of the treatment system that is not an electrode). Thus, a lower amount of fluid expelled at or near the sensor (e.g., as compared to systems that do not use thermal shunts, systems that include traditional heat transfer components, systems that rely primarily or critically on heat transfer between the electrode (and/or tissue) and blood traveling near the electrode (and/or tissue), other open irrigation systems, etc.) may increase the accuracy of temperature measurements obtained by sensors located at or near the distal end of a catheter or other medical instrument.

Moreover, since the irrigation fluid may be delivered at a lower flow rate characterized by a laminar flow profile (e.g., as opposed to a turbulent flow profile as may be required when the irrigation flow rate is higher), any disruptive hydrodynamic effects due to the higher flow rate may be advantageously avoided or at least reduced. Thus, laminar flow of fluid (and/or in combination with significantly lower flow rates of fluid as compared to higher flow systems) may contribute to the accuracy of temperature measurements of sensors located near the electrodes, the tissue being treated, and/or any other location along the distal end of a catheter or other medical instrument.

Furthermore, since the thermal shunt components located along or near the electrodes are very effective in transferring heat away from the electrodes and/or adjacent tissue of the subject being treated without retaining the transferred heat, the need to have longer electrodes and/or larger heat transfer members or portions may be advantageously eliminated. For example, conventional systems that utilize one or more heat transfer members (e.g., as opposed to and opposite a thermal shunt member) or systems that do not use any heat transfer members or components at all rely on heat transfer between the electrode and the surrounding environment (e.g., blood flowing past the electrode, a flushing fluid passing through the interior of the catheter, etc.) in an attempt to cool the electrode. As a result, the length, size, and/or other dimensions of the electrode or conventional heat transfer member need to be increased. This is done to increase the surface area for improved heat transfer between the electrodes and/or heat transfer member and the fluid (e.g., blood, irrigation fluid, etc.) that will provide heat transfer. However, in various embodiments disclosed herein, it is advantageously not necessary to provide electrodes and/or thermal shunt components or other components of the thermal shunt network with such increased surface area. Thus, the electrodes may be sized based on desired ablation/heating and/or mapping (e.g., high resolution) properties without having to be oversized based on heat transfer capabilities. Such oversizing can adversely affect the safety and effectiveness of the lesion formation process.

Thus, as discussed herein, in some embodiments, the size of the heat transfer member may be advantageously reduced (e.g., compared to the size of the heat transfer member in conventional systems). Heat generated during the course of treatment can be efficiently and quickly transferred away from the electrode and/or tissue being treated via the thermal shunt network without concern that such a network will retain the transferred heat. In some embodiments, heat may be diverted to the irrigation fluid passing through the interior of the catheter or other medical device. In other embodiments, heat may be transferred to the subject's surrounding bodily fluids (e.g., blood) via a thermal shunt member positioned along the exterior of a catheter or other medical device in addition to or instead of thermal shunting to the irrigation fluid.

According to some embodiments, the overall length (e.g., along the longitudinal direction) of the thermal shunt member extending to the exterior of the catheter or other medical instrument (such as, for example, in the configuration depicted in fig. 13-17B) may be 1 to 3mm (e.g., 1-1.5, 1.5-2, 2-2.5, 2.5-3mm, lengths between the foregoing, etc.). As described above, the thermal shunt member can effectively transfer heat away from the electrode and/or ablated tissue without retaining the heat despite the relatively short exposed length.

According to some embodiments, the total length (e.g., in the longitudinal direction) of the thermal shunt member extending along the interior of the catheter or other medical device (such as, for example, in the configuration depicted in fig. 13-17B) may be 1 to 30mm (e.g., 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-20, 20-25, 25-30mm, lengths between the aforementioned values, etc.). As noted above, despite a relatively short overall length, the thermal shunt member can effectively transfer heat from the electrode and/or ablated tissue to the fluid passing through the irrigation channel of the catheter or other medical device without retaining the heat.

According to some embodiments, the total length (e.g., in the longitudinal direction) of the thermal shunt member plus electrode extending along the interior of the catheter or other medical device (such as, for example, in the configuration depicted in fig. 13-17B) may be 1 to 30mm (e.g., 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-20, 20-25, 25-30mm, lengths between the foregoing, etc.). As noted above, despite a relatively short overall length, the thermal shunt member can effectively transfer heat from the electrode and/or ablated tissue to the fluid passing through the irrigation channel of the catheter or other medical device without retaining the heat.

As shown in fig. 13, the interior of the distal end of the catheter or other medical instrument may include a cooling chamber or region 1820 in fluid communication with the irrigation tube or channel 1804. As shown, the cooling chamber 1820 has a diameter or cross-sectional dimension that is larger than a diameter or cross-sectional dimension of the fluid conduit or passage 1804, according to some embodiments. For example, in some arrangements, the diameter or other cross-sectional dimension of the cooling chamber or region 1820 is about 1 to 3 times (e.g., 1 to 1.1, 1.1 to 1.2, 1.2 to 1.3, 1.3 to 1.4, 1.4 to 1.5, 1.5 to 1.6, 1.6 to 1.7, 1.7 to 1.8, 1.8 to 1.9, 1.9 to 2.0, 2.0 to 2.1, 2.1 to 2.2, 2.2 to 2.3, 2.3 to 2.4, 2.4 to 2.5, 2.5 to 2.6, 2.6 to 2.7, 2.7 to 2.8, 2.8 to 2.9, 2.9 to 3, values between the foregoing, etc.) the diameter or cross-sectional dimension of the fluid conduit or channel 1804, as desired or required. In other embodiments, the diameter or other cross-sectional dimension of the cooling chamber or region 1820 is about 3 times (e.g., 3 to 3.5, 3.5 to 4, 4 to 5, values in between, greater than 5, etc.) greater than the diameter or cross-sectional dimension of the fluid conduit or channel 1804. In other embodiments, the diameter or cross-sectional dimension of the cooling chamber or region 1820 is similar to or the same as (or smaller than) the diameter or cross-sectional dimension of the fluid conduit or passage 1804, as desired or required.

Fig. 14 shows a distal end of a catheter or other medical device of another embodiment of an ablation system 1900. As shown, the catheter includes one or more energy delivery members 1930 (e.g., a split-tip composite RF electrode, another type of electrode, another ablation member, etc.) along its distal end 1910. Similar to fig. 13, the depicted arrangement includes an active cooling system that uses one or more fluid conduits or channels that extend at least partially through the interior of a catheter or other medical instrument.

With continued reference to fig. 14, the catheter or medical device of the ablation system 1900 includes a closed irrigation system (e.g., a non-open irrigation system) in which a cooling fluid (e.g., saline) is circulated at least partially through the interior of the catheter (to and/or near the location of the electrodes or other energy delivery members) to transfer heat away from the electrodes or other energy delivery members. As shown, the system can include two separate tubes or channels 1904, 1906 that extend at least partially through the interior of a catheter or other medical instrument configured for placement within and/or near a target tissue of a subject. In some embodiments, one fluid conduit or channel 1904 is configured to deliver a fluid (e.g., saline) to the distal end of the catheter or device (e.g., adjacent to the electrode, ablation member, or other energy delivery member), while a separate tube or channel 1906 is configured to return cooling fluid delivered to or near the distal end of the catheter or other medical device proximally. In other embodiments, more than one channel or conduit delivers fluid to the distal end, and/or more than one channel or conduit returns fluid from the distal end, as desired or required.

In the embodiment of fig. 14, the fluid delivery conduit or channel 1904 is in fluid communication with a cooling chamber or region 1920 extending within the interior of the electrode or other energy delivery member 1930. In the depicted arrangement, the outlet 1905 of the fluid delivery conduit or channel 1904 is located at a position proximal to the distal end or inlet 1907 of the fluid return conduit or channel 1906. Thus, in the illustrated embodiment, the cooling chamber or region 1920 generally extends between the outlet 1905 of the fluid delivery conduit or passage 1904 and the inlet 1907 of the fluid return conduit or passage 1906. However, in other embodiments, the length, orientation, location, and/or other details of the cooling chamber or portion 1920 may be varied as desired or required. Further, in some embodiments, a catheter or other medical instrument may include a closed fluid cooling system (e.g., where a cooling fluid is circulated through the catheter or medical instrument) without including a separate cooling chamber or portion. Regardless of the exact orientation of the various fluid delivery and/or return lines (e.g., channels, conduits, etc.) of the catheter or medical instrument in the closed-loop fluid cooling system, the fluid will simply circulate through at least a portion of the catheter or other medical instrument (e.g., near and/or around the energized electrode or energy delivery member) to selectively and advantageously transfer heat away from the electrode or energy delivery member. Thus, in such embodiments, various fluid conduits or channels are in thermal communication with the electrodes or other energy delivery members.

In some embodiments, it is advantageous to transfer heat away from the electrodes (or other energy delivery members) of the ablation system, and thus from the target tissue of the subject, without the need to drain or vent a cooling fluid (e.g., saline) into the subject. For example, in some arrangements, draining saline or other cooling fluid to the heart, blood vessels, and/or other target areas of a subject can have negative physiological consequences (e.g., heart failure) for the subject. Thus, in some embodiments, it is preferred to treat a subject with an ablation system that: the ablation system includes a catheter or other medical device with a closed fluid cooling system or no active fluid cooling system throughout.

As with the embodiment of fig. 14 (and/or other embodiments disclosed herein), the depicted catheter includes one or more thermal shunt members 1950 in thermal communication with electrodes, ablation members, or other energy delivery members 1930 of the system 1900. As discussed above, the thermal shunt member 1950 may include industrial diamond, graphene, silicon dioxide, other carbon-based materials with good thermal diffusion properties, and/or the like. In some embodiments, the thermal diffusivity of the material(s) included in the thermal shunt member and/or the entire thermal shunt network or assembly (e.g., when considered as a unitary member or structure) is greater than 1.5cm²Per second (e.g., 1.5-2, 2-2.5, 2.5-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, etc.),10-11、11-12、12-13、13-14、14-15、15-20cm²A value between the aforementioned ranges, greater than 20cm²In seconds).

Fig. 15 illustrates yet another embodiment of a catheter or other medical device of an ablation system 2000, the ablation system 2000 can include one or more heat transfer members 2050 (e.g., thermal shunt members) along and/or near its distal end 2010. Unlike the arrangements of fig. 13 and 14 discussed herein, the depicted embodiment does not include an active fluid cooling system. In other words, a catheter or other medical device does not include any fluid conduits or channels. Rather, in some embodiments, as shown in fig. 15, the distal end of the catheter includes one or more inner members (e.g., inner structural members) 2070 along the interior thereof. Such an inner member 2070 may comprise a member or material having good heat diffusion characteristics. In some embodiments, the inner member 2070 includes the same or similar thermal diffusion properties or attributes as the thermal shunt member 2050, such as, for example, industrial diamond or graphene. In some embodiments, the material(s) included in the inner member 2070 and/or the entire thermal shunt network or assembly (e.g., when considered as a unitary member or structure) have a thermal diffusivity greater than 1.5cm²Per second (e.g., 1.5-2, 2-2.5, 2.5-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-20 cm)²A value between the aforementioned ranges, greater than 20cm²In seconds). However, in other embodiments, the inner member(s) do not include high thermal shunt materials and/or members. However, in other embodiments, the inner member 2070 does not include materials or members similar to those of the thermal shunt member 2050. For example, in some arrangements, the inner member(s) 2070 may comprise one or more components or members including a core having less than 1cm²Thermal diffusivity per second material(s).

With continued reference to the embodiment of fig. 15, a volume along the distal end of the catheter or medical device includes a structural member that at least partially occupies the volume. This is in contrast to other embodiments disclosed herein, wherein at least a portion of the distal end of the catheter or medical instrument includes a lumen (e.g., a cooling chamber) configured to receive a cooling fluid (e.g., saline) as such cooling fluid is delivered and/or circulated through the catheter or medical instrument.

In embodiments such as the embodiment shown in fig. 15, where no active fluid cooling is incorporated into the design of the catheter or other medical device of the ablation system 2000, the heat generated by the electrode (or other energy delivery member) 2030 and/or at the electrode (or other energy delivery member) 2030 may be more uniformly dissipated along the distal end of the catheter or medical device due to the heat dissipation properties of the heat transfer member 2050 (including, but not limited to, the heat shunt member (and/or inner member 2070, to the extent inner member 2070 also includes good heat shunt properties, e.g., a material with good heat spreading characteristics.). accordingly, the heat shunt member 2050 may help dissipate heat away from the electrode (or other energy delivery member) (e.g., via direct or indirect thermal contact with the electrode or other energy delivery member), to reduce the likelihood of any local hot spots (e.g., along the distal and/or proximal ends of the electrodes or other energy delivery members). Thus, with the aid of thermal shunt members 2050, heat can be more evenly distributed along a larger volume, area, and/or portion of the catheter. As discussed above, the use of a thermal shunt member can quickly and efficiently transfer heat away from the electrode and the tissue being treated during use. Relatively rapid heat transfer can be accomplished using materials that include good heat spreading properties without the negative effects of heat retention (e.g., which may otherwise lead to charring, thrombosis, and/or other heat related problems).

Further, in some embodiments, the flow of blood or other natural bodily fluids of the subject (within which the catheter or medical device is positioned) may facilitate the removal of heat from the electrodes or other energy delivery members. For example, the continuous flow of blood adjacent the exterior of the catheter during use may assist in the removal of heat from the distal end of the catheter. Such heat transfer may be further enhanced or otherwise improved by the presence of one or more thermal shunt members in thermal communication with the exterior of the conduit. For example, in some arrangements such as shown in fig. 15, one or more thermal shunt members 2050 can extend outside of a catheter or other medical device. Thus, when a catheter or medical device is inserted into a subject during use, heat can be advantageously transferred through thermal shunt member 2050 to blood (and/or other bodily fluids) moving near the catheter as the blood (and/or other bodily fluids) moves through the catheter or other medical device. Again, using a thermal shunt material with good thermal spreading properties will ensure that heat is not retained within such material, creating a safer ablation system and treatment process.

Fig. 16A and 16B illustrate another embodiment of a catheter or other medical device of an ablation system 2100, which ablation system 2100 may include one or more heat transfer members 2050 (e.g., thermal shunt members) along and/or near its distal end. Unlike other embodiments disclosed herein, the illustrated system includes a proximal electrode or electrode portion 2130, which proximal electrode or electrode portion 2130 extends deeper into the interior of the catheter. For example, as depicted in the side cross-sectional view of fig. 16B, the proximal electrode 2130 can extend outside or near the irrigation channel 2120. As discussed herein, the irrigation channel 2120 may comprise one or more metals, alloys, and/or other rigid and/or semi-rigid materials, such as, for example, stainless steel.

With continued reference to fig. 16A and 16B, the proximal electrode or proximal electrode portion 2130 can be part of a composite (e.g., split tip) electrode system according to various composite embodiments disclosed herein. Thus, in some embodiments, to make the split tip electrode configuration operate properly, the distal electrode 2110 is electrically isolated from the proximal electrode 2130. In the illustrated configuration, since the proximal electrode 2130 extends to or near the metallic (and thus electrically conductive) irrigation tube 2120, at least one electrically insulating layer, coating, member, portion, barrier, and/or the like 2128 may advantageously be positioned between the electrode 2130 and the irrigation tube 2120. In some embodiments, for example, the electrically insulating member 2128 comprises one or more layers of polyimide, other polymeric materials, and/or another electrically insulating material, as desired or required. Such an electrically insulating layer and/or other member 2128 may replace the diamond and/or another electrically insulating thermal shunt member, which may additionally be positioned around the irrigation tube 2120 to electrically isolate the distal electrode 2110 from the proximal electrode 2130.

The proximal and/or distal electrodes 2130, 2110 can include one or more metals and/or alloys according to any of the embodiments disclosed herein. For example, the electrodes may comprise platinum, stainless steel, and/or any other biocompatible metal and/or alloy. Thus, in some embodiments, the thicker proximal electrode 2130 that extends to or near the irrigation tube 2120 may be referred to as a "slug," e.g., a "platinum slug. As discussed, in such an arrangement, the need for internal diamonds and/or other thermal shunt members may be eliminated. Alternatively, in such embodiments, as shown in fig. 16B, the proximal and distal ends of a "slug" or thicker proximal electrode 2130 can be placed in thermal communication with one or more thermal shunt members (e.g., diamonds) to help shunt heat away from the electrode 2130 and/or the treated tissue of the subject. Thus, in some embodiments, the proximal surface and/or the distal surface of the proximal electrode or block 2130 can be placed in good thermal contact with an adjacent thermal shunt member, as desired or required.

With continued reference to fig. 16B, according to some embodiments, at least a portion 2222 of the irrigation tube 2120 is perforated and/or has one or more openings 2123. In some embodiments, such openings 2123 can place irrigation fluid carried within the interior of the irrigation channel 2120 in direct physical and thermal communication with an adjacent thermal shunt member (e.g., diamond, graphene, silicon dioxide, etc.) to quickly and efficiently transfer heat away from the electrode and/or tissue being treated. In some embodiments, direct physical and/or thermal communication between the flushing fluid and the flow diversion member facilitates providing improved heat transfer to the flushing fluid (e.g., saline) passing through the interior of the flushing passage 2120. In the illustrated embodiment, the openings 2123 along the perforated portion 2222 are generally circular in shape and are evenly distributed relative to one another (e.g., include a substantially even distribution or spacing relative to one another). However, in other arrangements, the size, shape, spacing, and/or other characteristics of the perforations along the channel 2120 or the openings 2123 of the direct contact region 2122 may vary as desired or required. For example, in some embodiments, the openings 2123 can be oval, polygonal (e.g., square or rectangular, triangular, pentagonal, hexagonal, octagonal, etc.), irregular, and/or the like. In some embodiments, the openings are slotted or elongated.

Regardless of their exact shape, size, orientation, spacing, and/or other details, the openings 2123 comprising the perforations of the channels 2120 or the direct contact regions 2122 may provide direct contact between the flushing fluid and the adjacent diamonds (and/or another thermal shunt member) 1150 of up to 30% to 70% (e.g., 30-35, 35-40, 40-45, 45-50, 50-55, 55-60, 60-65, 65-70%, percentages between the aforementioned ranges, etc.) of the surface area of the perforations of the channels 2120 or the direct contact regions 2122. In other embodiments, the openings 2123 of the perforated or direct contact region 2122 comprising the channels 2120 may provide direct contact between the rinsing fluid and the adjacent diamonds (and/or another thermal shunt member) 2150 up to less than 30% (e.g., 1-5, 5-10, 10-15, 15-20, 20-25, 25-30%, percentages between the aforementioned ranges, less than 1%, etc.) or more than 70% (e.g., 70-75, 75-80, 80-85, 85-90, 90-95, 95-99%, percentages between the aforementioned ranges, more than 99%, etc.) of the surface area of the perforated or direct contact region 2122 of the channels 2120, as desired or required. Such a perforated or direct contact region 2122 may be incorporated into any of the embodiments disclosed herein. Additionally, any of the embodiments disclosed herein (including, but not limited to, the systems of fig. 16A and 16B) may include more than one perforation or direct contact area 2122. For example, the embodiment of fig. 16A and 16B may include a second perforation or direct contact area along the distal end of the proximal mass or electrode 2130 and/or along any other portion adjacent to the thermal shunt member.

As shown in fig. 16B, a distal end of an irrigation tube (e.g., a flexible polyurethane or other polymer tubing) 2104 may be positioned at least partially within the interior of such a channel 2120, the irrigation tube 2104 in fluid communication with an irrigation channel 2120, the irrigation channel 2120 extending through the distal end of a catheter or other medical instrument. Such a configuration may be incorporated into any of the embodiments disclosed herein or variations thereof. In some embodiments, the distal portion of the irrigation tube 2104 is sized, shaped, and/or the distal portion of the irrigation tube 2104 is otherwise configured to be press-fit (press-fit) inside the distal channel 2120. However, in some embodiments, one or more other attachment devices or methods (such as, for example, adhesives, thermal bonding (bonding), fasteners, etc.) may be used to help secure the irrigation tube 2104 to the irrigation channel 2120, as desired or required.

Another embodiment of the distal end of a catheter or other medical instrument 2200 is shown in fig. 16C, the catheter or other medical instrument 2200 including proximal 2230 and distal 2210 electrodes and a thermal shunt feature. As shown, the proximal electrode or block 2230 extends toward the interior of the catheter (e.g., to or near the irrigation channels 2104, 2220). However, the depicted electrode 2230 is generally thinner (e.g., extends less far than the embodiment of fig. 16A and 16B) than the embodiment of fig. 16A and 16B. In the illustrated embodiment, one or more heated shunt members (e.g., diamond, graphene, silicon dioxide, etc.) having good thermal diffusion properties are positioned between the interior of the proximal electrode or block 2230 and the irrigation channels 2220. Thus, in such an arrangement, not only can heat generated at or along electrode 2230 and/or the subject's treated tissue be more quickly and efficiently transferred away from the electrode and/or tissue, but diamond or other electrically insulating thermal shunt member or network 2250 provides the necessary electrical insulation between metal (e.g., stainless steel) irrigation channel 2220 and the proximal electrode or block 2230. As described herein, such electrical isolation is helpful for complex (e.g., split tip) designs.

In fig. 17A and 17B, a distal portion 2300 of another embodiment of an ablation system is shown. As shown, the system includes a composite (e.g., split tip) design with a proximal electrode or block 2330 and a distal electrode 2310. In addition, the catheter or other medical instrument includes one or more heat transfer members 2350, the one or more heat transfer members 2350 including, but not limited to, a thermal shunt network (e.g., including diamond, graphene, silicon dioxide, and/or other materials having good thermal diffusion properties). According to some embodiments, as depicted in the illustrated arrangement, thermal shunt network 2350 may include a ring extending to the exterior of the catheter or instrument and/or one or more internal components positioned within (e.g., below) proximal electrode 2330, as desired or required. Additionally, as with other embodiments disclosed herein, one or more temperature sensors 2392, 2394 may be provided along one or more portions of the system (e.g., along or near the distal electrode 2310, along or near the proximal thermal shunt member, along or near the proximal electrode 2330, etc.) to help detect the temperature of the tissue being treated. As discussed in more detail, such temperature sensors (e.g., thermocouples) may also be used to detect the orientation of the tip to determine whether contact is being made between the tip and the tissue and/or the like (and/or to determine how much contact is being made between the tip and the tissue and/or the like).

With continued reference to the embodiment of fig. 17A and 17B, a catheter or other medical device may include a proximal link or member 2340. As shown, such a coupling or member 2340 is configured to be connected to a flush tube (e.g., polyurethane, other polymer or other flexible tubing, etc.) 2304 and placed in fluid communication with the flush tube 2304. For example, in the illustrated embodiment, the distal end of the irrigation conduit 2304 is sized, shaped, and the distal end of the irrigation conduit 2304 is otherwise configured to be inserted within the proximal end (e.g., recess) of the coupling 2340. In some embodiments, the flush tube 2304 is press fit into a recess of the coupling 2340. However, in other arrangements, instead of or in addition to a press-fit connection, one or more other attachment devices or methods may be used to secure the tube 2304 to the coupling 2340 (e.g., adhesives, welds, fasteners, etc.), as desired or required. Regardless of the exact mechanism of securement between the flush tube 2304 and the coupling 2340, fluid passing through the tube 2304 may enter the manifold 2342 of the coupling 2340. In some embodiments, the manifold 2342 may divide the flow of flushing fluid into two or more pathways 2344. However, in some embodiments, the coupling 2340 does not have a manifold. For example, flushing fluid entering the coupling 2340 may be directed along only a single fluid path, as desired or required.

In the embodiment of fig. 17A and 17B, the manifold (or other flow path dividing feature, apparatus, or component) 2342 of the coupling 2340 splits the flushing flow into three different fluid paths. As shown, each such fluid path may be placed in fluid communication with a separate fluid conduit or sub-conduit 2320. In some embodiments, such fluid conduits 2320 are equally spaced (e.g., radially) relative to a centerline of the catheter or other medical instrument. For example, the pipes 2320 may be spaced at 120 degrees or approximately at 120 degrees relative to each other. As shown, the conduit 2320 extends at least partially through the proximal thermal shunt member 2350 and the proximal block or electrode 2330. However, in other embodiments, the orientation, spacing, and/or other details of the manifolds 2342, 2344 and/or the fluid conduits 2320 may vary. Additionally, the number of fluid conduits 2320 originating from the manifold system may be greater than 3 (e.g., 4, 5, 6, 7, greater than 7, etc.) or less than 3 (e.g., 1, 2), as desired or required.

In some embodiments where the system includes an open irrigation system, as shown in the longitudinal cross-sectional view of fig. 17B, one or more irrigation fluid outlets 2332a, 2332B, 2332c may be provided along one or more of the fluid conduits 2320. As shown, such a fluid outlet 2332 can be disposed within the proximal electrode 2330. However, in other embodiments, such an outlet 2332 can be included within one or more other portions of the system (e.g., the thermal shunt member 2350, the distal electrode 2310, etc.) instead of or in addition to the proximal electrode 2330. Such configurations (e.g., configurations that include a manifold and/or openings through the proximal electrode) may be incorporated into any of the ablation system embodiments disclosed herein. When utilizing other irrigation system arrangements disclosed herein, heat can be shunted (e.g., from the electrodes, the tissue being treated, one or more other portions of the system, etc.) to the irrigation fluid passing through the conduits and/or fluid outlets to help quickly and efficiently dissipate (e.g., shunt) heat from the system during use. In some embodiments, as shown in fig. 17A and 17B, the relative size, shape, and/or other configuration of two or more of the fluid outlets 2332 may vary. For example, in some arrangements, to better balance the fluid hydraulics of the fluid passing through each conduit 2320 (e.g., to better balance the flow rate through each outlet 2332), the proximal fluid outlet may be smaller than one or more of the distal fluid outlets. However, in other embodiments, two or more (e.g., most or all) of the fluid outlets 2332 include the same shape, size, and/or other properties.

In some embodiments, the orientation of the fluid outlets may be inclined relative to the radial direction of the catheter or other medical device in which they are located. Such tilting or offsetting may occur with respect to any fluid outlet located along the distal end of a catheter or other medical instrument (e.g., a fluid outlet located along a distal electrode as shown in fig. 13, 16A and 16B and 16C, a fluid outlet located along a proximal electrode as shown in fig. 17A and 17B, etc.). The degree to which the outlet is tilted or offset (e.g., relative to the radial direction of the catheter or medical device, relative to a direction perpendicular to the longitudinal centerline of the catheter or medical device) may be varied as desired or required. For example, the fluid openings may be inclined or offset from the radial direction by 0 to 60 degrees (e.g., 0-5, 5-10, 10-15, 15-20, 20-25, 25-30, 30-35, 35-40, 40-45, 45-50, 50-55, 55-60 degrees, angles between the aforementioned ranges, etc.). In some embodiments, the fluid openings are inclined or offset more than 60 degrees (e.g., 60-65, 65-70, 70-75 degrees, angles between the aforementioned ranges, greater than 70 degrees, etc.) relative to the radial direction, as desired or required.

According to some embodiments, the fluid outlet or opening located along or near the distal electrode is tilted or offset distally (e.g., in a direction distal to the location of the corresponding fluid outlet or opening). In some embodiments, the fluid outlets or openings located along or near the proximal electrode are tilted or offset proximally (e.g., in a direction proximal of the location of the corresponding fluid outlet or opening). Thus, in some embodiments, irrigation fluid exiting at or near the distal electrode is delivered in a direction distal to the corresponding fluid outlet(s), while irrigation fluid exiting at or near the proximal electrode is delivered in a direction proximal to the corresponding fluid outlet(s). In some embodiments, such a configuration may help cool hot spots that may otherwise be created along or near the electrode. Such a configuration may also help dilute the blood in those areas to help reduce the likelihood of thrombus and/or clot formation.

Multiple temperature sensors

According to some embodiments, a medical instrument (e.g., an ablation catheter) may include a plurality of temperature measurement devices (e.g., thermocouples, thermistors, other temperature sensors) axially spaced at different locations along a distal portion of the medical instrument. The axial spacing advantageously facilitates measurement of meaningful spatial temperature gradients. Each of the temperature measurement devices may be isolated from each of the other temperature measurement devices to provide independent temperature measurements. The temperature measurement device may be thermally and/or electrically insulated or isolated from one or more energy delivery member(s) (e.g., radiofrequency electrodes) so as not to directly measure the temperature of the energy delivery member(s), thereby facilitating temperature measurement isolated from the thermal effect of the energy delivery member(s). The medical instrument may include a first plurality (e.g., set, array, set) of temperature-measurement devices (e.g., sensors) positioned at or near a distal tip or end of the medical instrument (e.g., within a distal electrode portion of a high resolution unitized electrode assembly or a composite electrode assembly) that may be spaced apart (e.g., circumferentially, radially) along a first cross-section of the medical instrument in an equidistant manner or a non-equidistant manner around the medical instrument. In one embodiment, the first plurality of temperature measurement devices are positioned symmetrically about a longitudinal axis of the distal end of the medical instrument. The medical instrument may also include a second plurality of temperature-measurement devices (e.g., sensors) spaced proximally from the first plurality of temperature-measurement devices along a second cross-section of the medical instrument (which is proximal to the first cross-section) allowing temperature measurements to be obtained at a plurality of spaced-apart locations. In some embodiments, the second plurality of temperature-measurement devices is positioned near a proximal end (e.g., edge) of an electrode or other energy delivery member (if the medical instrument (e.g., ablation catheter) includes a single electrode or other energy delivery member) or a proximal-most electrode or other energy delivery member (if the medical instrument includes multiple electrode members or other energy delivery members).

Temperature measurements obtained from a temperature measurement device (e.g., a sensor) may be advantageously used to determine, among other things, an orientation of a distal tip of a medical instrument relative to a tissue surface, an estimated temperature of a peak temperature zone of a lesion formed by the medical instrument (e.g., an ablation catheter), and/or an estimated location of the peak temperature zone of the lesion. In some embodiments, determinations made using temperature sensors or other temperature measurement devices may be used to adjust treatment parameters (e.g., target temperature, power, duration, orientation) in order to prevent charring or thrombus if used in a blood vessel, and/or to control lesion parameters (e.g., depth, width, location of peak temperature zone, peak temperature) to provide a more reliable and safer course of treatment (e.g., ablation). Thus, in implementing a control scheme that regulates the delivery of power or other parameters to an energy delivery member (e.g., RF electrode, microwave emitter, ultrasound transducer, cryogenic emitter, other emitter, etc.) positioned along the distal end of a medical device (e.g., catheter, probe, etc.), a target treatment level can be achieved without negatively affecting (e.g., overheating, overtreatment, etc.) the tissue of the subject (e.g., within and/or near the treatment volume).

The term peak temperature as used herein may include a peak or high temperature (e.g., a positive peak temperature) or a trough or low temperature (e.g., a negative peak temperature). As a result, determining a peak temperature (e.g., a maximum or minimum temperature or other extreme temperature) within the target tissue may result in a safer, more efficient, and more efficacious treatment process. In some embodiments, for example when performing cryoablation, the systems, devices, and/or methods disclosed herein may be used to determine a trough or lowest temperature point within a treatment (e.g., ablation) volume. In some embodiments, techniques of cooling tissue face similar clinical challenges of controlling tissue temperature within a range of efficacious and safe temperatures. Thus, the various embodiments disclosed herein may be used with techniques to cool or heat a target tissue.

Several embodiments of the invention are particularly advantageous as they include one, several or all of the following advantages: (i) reducing proximal edge heating, (ii) reducing the likelihood of charring or thrombosis, (iii) feedback that can be used to adjust the ablation process in real time, (iv) non-invasive temperature measurements, (v) determining the electrode-tissue orientation within a short time after initiating energy delivery; (vi) a safer and more reliable ablation procedure; and (vii) tissue temperature monitoring and feedback during irrigated or non-irrigated ablation.

Fig. 18A shows a perspective view of the distal portion of an open irrigated ablation catheter 3120A including a plurality of temperature measurement devices 3125 according to one embodiment. As shown, the embodiment of the ablation catheter 3120A of fig. 18A is an open irrigated catheter that includes a high resolution unitized electrode assembly or composite (e.g., split tip) electrode design. The composite electrode design includes a dome or hemispherical distal tip electrode member 3130, an insulating gap 3131, and a proximal electrode member 3135. The ablation catheter 3120A includes a plurality of irrigation ports 3140 and a heat transfer member 3145 (e.g., a thermal shunt member).

The temperature measurement devices 3125 include a first (e.g., distal) set of temperature measurement devices 3125A positioned in notches or holes formed in the distal electrode member 3130 and a second (e.g., proximal) set of temperature measurement devices 3125B positioned in slots, indentations, or openings formed in the heat transfer member 3145 near or adjacent to the proximal edge of the proximal electrode member 3135. The temperature measurement device 3125 may include a thermocouple, a thermistor, a fluorescence sensor, a resistance temperature sensor, and/or other temperature sensors. In various embodiments, the thermocouples comprise nickel alloys, platinum/rhodium alloys, tungsten/rhenium alloys, gold/iron alloys, precious metal alloys, platinum/molybdenum alloys, iridium/rhodium alloys, pure precious metals, type K, T, E, J, M, N, B, R, S, C, D, G, and/or P thermocouples. The reference thermocouple may be positioned at any location along the catheter 3120A (e.g., in the handle of the catheter 3120A or within a shaft or elongated member). In one embodiment, the reference thermocouple is thermally and/or electrically insulated from the electrode member(s). The electrode member(s) may be replaced with other energy delivery members.

In some embodiments, the temperature measurement device is thermally insulated from the electrode members or portions 3130, 3135 in order to isolate the temperature measurement from thermal effects of the electrode members (e.g., to facilitate measuring ambient temperature (such as tissue temperature) rather than measuring the temperature of the electrode members). As shown, the temperature measurement device 3125 may protrude or extend outwardly from the outer surface of the ablation catheter 3120A. In some embodiments, the temperature measurement device 3125 can protrude up to about 1mm from the outer surface (e.g., from about 0.1mm to about 0.5mm, from about 0.5mm to about 1mm, from about 0.6mm to about 0.8mm, from about 0.75mm to about 1mm, or overlapping ranges thereof). According to several embodiments, the dome shape of the distal tip electrode member 3130 and/or the outward protrusion or extension of the temperature measurement device 3125 may advantageously allow the temperature measurement device to be embedded deeper into tissue and away from the effects of the open irrigation provided by the irrigation port 3140. The proximal set of temperature measurement devices and the distal set of temperature measurement devices may protrude by the same amount or by different amounts (as a set and/or individually within each set). In other embodiments, the temperature measurement device 3125 is flush or embedded within an outer surface of the elongated body of the medical instrument (e.g., 0.0mm, -0.1mm, -0.2mm, -0.3mm, -0.4mm, -0.5mm from the outer surface). In some embodiments, the distal temperature measurement device 3125A protrudes or extends distally from the distal outer surface of the distal electrode member, and the proximal temperature measurement device 3125B is flush within the lateral outer surface of the elongate body of the ablation catheter 3120A.

Referring to fig. 18D, at least some of the positioned portions of the temperature measurement device 3125 in the ablation catheter 3120C may have a larger outer diameter or other outer cross-sectional dimension than adjacent portions of the ablation catheter 3120C in order to facilitate deeper burial of at least some of the temperature measurement device within tissue and further isolate the temperature measurement from thermal effects of the electrode member or fluid (e.g., saline or blood). As shown in fig. 18D, the portion of the proximal group 3125B of the ablation catheter 3120C that includes the temperature measurement device includes a protrusion, ring, or ridge 3155 having a larger outer diameter than the adjacent portion.

In some embodiments, the temperature measurement device 3125 is adapted to be advanced outwardly and retracted inwardly. For example, the temperature measurement device 3125 can be in a retracted position (within the outer surface or protruding slightly outward) during insertion and movement of the ablation catheter to the treatment position to reduce the outer profile and facilitate insertion to the treatment position, and can be advanced outward while at the treatment position. The features described above in connection with the ablation catheter 3120C of fig. 18D may be used with any of the other ablation catheters described herein.

Returning to fig. 18A, the proximal and distal sets of temperature measurement devices 3125 may each include or consist of two, three, four, five, six, or more than six temperature measurement devices. In the illustrated embodiment, the proximal and distal sets of temperature measurement devices 3125 are each made up of three temperature measurement devices, which may provide a balance between volume coverage and reduced part count. The number of temperature measurement devices 3125 may be selected to balance accuracy, complexity, volume coverage, tip-to-tissue apposition (apposition) variation, cost, number of components, and/or size constraints. As shown in fig. 18A, the temperature measurement devices 3125 can be equally spaced about the circumference of the ablation catheter 3120A, or equally angularly spaced (e.g., symmetrically) from each other about a central longitudinal axis extending from the proximal end to the distal end of the ablation catheter. For example, when three temperature measurement devices are used, they may be spaced apart by about 120 degrees, and when four temperature measurement devices are used, they may be spaced apart by about 90 degrees. In other embodiments, the temperature measurement devices 3125 are not equally spaced.

As shown in the embodiment of fig. 18A, the temperature measurement devices 3125 of each group may be positioned along the same cross-section (e.g., coplanar) of the ablation catheter 3120A. For example, the distal temperature measurement devices 3125A may be positioned to extend outwardly from the dome-shaped surface the same distance, and the proximal temperature measurement devices 3125B may each be spaced the same distance from the distal tip of the ablation catheter 3120A. As shown in the embodiment of fig. 18A, the distal temperature measurement device 3125A extends from the distal outer surface of the distal electrode member in an axial direction that is parallel or substantially parallel to the central longitudinal axis of the distal portion of the ablation catheter 3120A, and the proximal temperature measurement device 3125B extends radially outward from the outer surface of the ablation catheter 3120A. In other embodiments, the distal temperature measurement device 3125A may not be positioned in or on the distal outer surface of the distal tip, but rather may be positioned on a side surface to extend radially outward (similar to the proximal temperature measurement device 3125B shown). In some embodiments, the temperature measurement devices 3125 are not spaced within each group in two separate groups of co-planar temperature measurement devices, but are otherwise spatially distributed.

As shown in the embodiment of fig. 18A, the distal temperature measurement device 3125A may be positioned distal of the insulating gap 3131 and/or the irrigation port 3140, and the proximal temperature measurement device 3125B may be positioned proximal of a proximal edge of the proximal electrode member 3135 within the heat transfer member 3145. In other embodiments, the proximal temperature measurement device 3125B may be positioned distal to a proximal edge of the proximal electrode member 3135 (e.g., within a notch or hole formed within the proximal electrode member 3135 (similar to the notch or hole formed in the distal tip electrode member shown in fig. 18A)). In other embodiments, the distal temperature measurement device 3125A and/or the proximal temperature measurement device 3125B may be positioned at other locations along the length of the ablation catheter 3120A. In some embodiments, each distal temperature measurement device 3125A is axially aligned with one of the proximal temperature measurement devices 3125B and the spacing between the distal temperature measurement device 3125A and the proximal temperature measurement device is uniform or substantially uniform.

The irrigation ports 3140 may be spaced (equidistant or otherwise) around the circumference of the shaft of the ablation catheter 3120A. The irrigation port 3140 communicates with a fluid source, such as the fluid source provided by the irrigation fluid system 70 of fig. 1. The irrigation ports facilitate an open irrigation and provide cooling to any blood surrounding electrode members 3130, 3135 and 3130, 3135. In some embodiments, the ablation catheter 3120A includes three, four, five, six, seven, eight, or more than eight exit ports 3140. In various embodiments, the exit port 3140 is spaced between 0.005 and 0.015 inches from the proximal edge of the distal electrode member 3130 in order to provide improved cooling of the heat transfer member 3145 at the tissue interface; however, other spacings may be used as desired and/or required. In other embodiments, the exit ports 3140 are linearly and/or circumferentially spaced along the proximal electrode member 3135 (e.g., as shown in fig. 18E).

Fig. 18B and 18C show perspective and cross-sectional views, respectively, of the distal portion of an open irrigated ablation catheter 3120B having multiple temperature measurement devices in accordance with another embodiment. The ablation catheter 3120B may include any or all of the structural components, elements, and features of the ablation catheter 3120A described above, and the ablation catheter 3120A may include any or all of the structural components, elements, and features described in connection with fig. 18B and 18C. The ablation catheter 3120B includes a flat tip electrode member 3130 instead of the dome-shaped tip electrode member shown in fig. 18A. In other words, the distal outer surface is flat or planar, rather than rounded or hemispherical. According to several embodiments, the distal temperature measurement device 3125A is positioned in or on a flat or planar surface, but not on a curved, annular, or arcuate surface of the distal tip electrode member that connects the distal outer surface and the lateral outer surface of the distal tip electrode member.

As best shown in fig. 18C, the thermal transfer member 3145 is in thermal contact with one or both of the electrode members 3130, 3135. The heat transfer member 3145 can extend to, near, or beyond the proximal end of the proximal electrode member 3135. In some embodiments, heat transfer member 3145 terminates at or near the proximal end of proximal electrode member 3135. However, in other arrangements (as shown in fig. 18C), the heat transfer member 3145 extends beyond the proximal end of the proximal electrode member 3135. In still other embodiments, the heat transfer member 3145 terminates distal of the proximal end (e.g., edge) of the proximal electrode member 3135. The heat transfer member 3145 can extend from the proximal surface of the tip electrode member 3130 to a location beyond the proximal end of the proximal electrode member 3135. Embodiments in which the heat transfer member 3145 extends beyond the proximal end of the proximal electrode member 3135 may provide increased shunting of the proximal edge heating effect caused by the amount of increased current concentration at the proximal edge by reducing the heat at the proximal edge by conductive cooling. In some embodiments, at least a portion of heat transfer member 3145 is in direct contact with tissue (e.g., within insulating gap 3131) and can directly remove or dissipate heat from the target tissue being heated.

The heat transfer member 3145 may comprise one or more materials that include good heat transfer properties. For example, in some embodiments, the thermal conductivity of the material(s) included in the heat transfer member is greater than 300W/m/deg.C (e.g., 300-. Possible materials with good thermal conductivity properties include, but are not limited to, copper, brass, beryllium, other metals and/or alloys, alumina, ceramics, other ceramics, industrial diamond, and/or other metallic and/or non-metallic materials.

According to certain embodiments in which the heat transfer member comprises a thermal shunt member, the thermal diffusivity of the material(s) included in the thermal shunt member and/or the entire shunt assembly (e.g., when considered as a unitary member or structure) is greater than 1.5cm²Per second (e.g., 1.5-2, 2-2.5, 2.5-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-0, 10-11, 11-12, 12-13, 13-14, 14-15, 15-20 cm)²A value between the aforementioned ranges, greater than 20cm²In seconds). Thermal diffusivity measures the ability of a material to conduct thermal energy relative to its ability to store thermal energy. Thus, even though a material may transfer heat efficiently (e.g., may have a relatively high thermal conductivity), it may not have good thermal diffusion properties due to its thermal storage properties. Unlike heat transfer, thermal shunting requires the use of materials that have high thermal conductivity properties (e.g., rapid transfer of heat through a mass or volume) and low thermal capacity (e.g., do not store heat). Possible materials with good thermal diffusivity and therefore good thermal shunting properties include, but are not limited to, industrial diamond, graphene, silica alloys, ceramics, other carbon-based materials, and/or other metallic and/or non-metallic materials. In various embodiments, the material used for thermal conduction (e.g., diamond) provides increased visibility to the catheter tip using ICE imaging or other imaging techniques.

The use of materials with good heat spreading properties can help ensure that heat can be efficiently transferred away from the electrodes and/or adjacent tissue during the course of treatment. Conversely, materials that have good thermal conductivity properties but do not have good thermal diffusion properties (such as, for example, copper, other metals or alloys, thermally conductive polypropylene or other polymers, etc.) will tend to retain heat. As a result, the use of such heat-storing materials may result in the temperature along the electrode and/or the tissue being treated being maintained at an undesirably elevated level (e.g., in excess of 75 degrees celsius), especially during relatively long ablation procedures, which may lead to charring, thrombosis, and/or other heat-related problems.

Industrial diamonds and other materials with the requisite thermal diffusion properties for use in thermal shunt networks include good thermal conduction properties, as disclosed in various embodiments herein. This good thermal conduction aspect results from the relatively high thermal conduction values and the way in which the thermal shunt members of the network are arranged relative to each other and to the tissue within the tip. For example, in some embodiments, when radiofrequency energy is emitted from the tip and ohmic heating within the tissue generates heat, the exposed distal-most shunt member (e.g., 0.5mm from the distal-most side of the tip) can actively extract heat from the injury site. Thermal energy may advantageously be transferred through the shunt network in a relatively fast manner and dissipated through the shunt residing below the surface of the radiofrequency electrode, the thermal shunt network, through the proximal shunt member, and/or into the ambient environment. Heat shunted by the inner shunt member can be quickly transferred to an irrigation conduit extending through the interior of a catheter or other medical device. In other embodiments, heat generated by the ablation process may be shunted by both proximal and distal shunt members (e.g., shunt members exposed to the exterior of a catheter or other medical device, such as shown in many embodiments herein).

Further, as described above, a material having good heat diffusion properties for a thermal shunt network has not only necessary thermal conductivity properties but also a sufficiently low value of thermal capacity. This helps to ensure rapid dissipation of thermal energy from the tip to tissue interface and hot spots on the electrode without retaining heat in the thermal shunt network. Thermal conduction constitutes the primary heat dissipation mechanism that ensures rapid and efficient cooling of the tissue surface and the radiofrequency electrode surface. Conversely, heat transfer (e.g., having relatively high thermal conductivity characteristics but also having relatively high heat capacity characteristics) will store thermal energy. During long ablation procedures, this stored heat may exceed 75 degrees celsius. In this case, thrombus and/or char formation may undesirably occur.

The heat convection aspect of the various embodiments disclosed herein is twofold. First, the flush lumen of the catheter may absorb thermal energy transferred to it through the shunt network. Such thermal energy may then be flushed away from the distal end of the electrode tip via the flushing port. However, in a closed irrigation system, this thermal energy may be transferred back to the proximal end of the catheter where it may be removed. Second, the exposed shunt surface along the exterior of the catheter or other medical device may further assist in dissipating heat from the electrode and/or tissue being treated. Such heat dissipation may be achieved, for example, via the inherent convective cooling aspects of blood flowing over the surface of the electrodes.

Thus, the use of a material with good heat spreading properties, such as industrial diamond, in the thermal shunt network may help ensure that heat is quickly and efficiently transferred away from the electrode and the treated tissue while maintaining the thermal shunt network cool (e.g., due to its low thermal capacity properties). This may create a safer ablation catheter and associated treatment method, as potentially dangerous heat is not introduced into the procedure via the thermal shunt network itself.

In some embodiments, the thermal shunt members disclosed herein draw heat from the ablated tissue and shunt it into the irrigation channel. Similarly, heat is extracted from potential hot spots formed at the edges of the electrodes and shunted into the irrigation channel through a thermal shunt network. Heat can be advantageously released from the irrigation channel into the blood stream via convective cooling and dissipated. In a closed irrigation system, heat can be removed from the system without draining irrigation fluid into the subject.

As shown in fig. 18C, the heat transfer member 3145 is also in thermal contact with a heat exchange chamber (e.g., irrigation conduit) 3150 extending along the inner lumen of the ablation catheter 3120B. For any of the embodiments disclosed herein, at least a portion of the heat transfer member (e.g., thermal shunt member) in thermal communication with the heat exchange chamber 3150 extends to an outer surface of the catheter, adjacent to (and, in some embodiments, in physical and/or thermal contact with) the one or more electrodes or other energy delivery member(s), such a configuration may further enhance cooling of the electrode(s) or other energy delivery member(s) when the system is activated, particularly at or near the proximal end of the electrode(s) or energy delivery member(s), where heat may otherwise tend to be more concentrated (e.g., relative to other portions of the electrode(s) or other energy delivery member). According to some embodiments, thermally conductive grease and/or any other thermally conductive material (e.g., thermally conductive liquid or other fluid, layer, member, coating, and/or portion) may be used to place the heat transfer member 3145 in thermal communication with the heat exchange chamber (e.g., flush tube) 3150, as desired or required. In such embodiments, such thermally conductive material places the electrode members 3130, 3135 at least partially in thermal communication with the irrigation conduit 3150.

The irrigation conduit(s) 3150 may be part of an open irrigation system in which fluid exits through an exit port or opening 3140 along the distal end of the catheter (e.g., at or near the electrode member 3130) to cool the electrode member and/or adjacent target tissue. In various embodiments, the flushing conduit 3150 includes one or more metals and/or other good heat transfer (e.g., heat diverting) materials (e.g., copper, stainless steel, other metals or alloys, ceramics, polymers, and/or other materials having relatively good heat transfer properties, etc.). The irrigation conduit 3150 may extend beyond the proximal end of the proximal electrode member 3135 and into a proximal portion of the heat transfer member 3145. The inner wall of the irrigation conduit 3150 may comprise a biocompatible material (such as stainless steel) that forms a strong weld or bond between the irrigation conduit 3150 and the material of the electrode member.

In some embodiments, the ablation catheter 3120 includes only irrigation exit openings 3140 along the distal end of the catheter (e.g., along the distal end of the distal electrode member 3130). In some embodiments, the system does not include any flushing openings along the heat transfer member 3145.

Heat transfer member 3145 can advantageously promote thermal conduction away from electrode members 3130, 3135, thereby further cooling electrode members 3130, 3135 and reducing the likelihood of charring or thrombosis if the electrode members are in contact with blood. In addition to thermal conduction, the heat transfer member 3145 may also provide enhanced cooling of the electrode members 3130, 3135 by facilitating convective heat transfer in conjunction with the flushing conduit 3150.

By eliminating air gaps or other similar spaces between the electrode members and the heat transfer members, heat transfer (e.g., thermal shunting) between the heat transfer members 3145 and the electrode members 3130, 3135 may be facilitated and otherwise enhanced. For example, one or more layers of conductive material (e.g., platinum, gold, other metals or alloys, etc.) may be positioned between the interior of the electrode member and the exterior of the heat transfer member 3145. Such layer(s) may be applied continuously or intermittently between the electrode member (or another type of ablation member) and the adjacent heat transfer member. Further, such layer(s) may be applied using one or more methods or processes, such as, for example, sputtering, other plating techniques, and/or the like. Such layer(s) may be used in any of the embodiments disclosed herein or variations thereof. In addition, the use of a thermal shunt network may specifically help to transfer heat away from the tissue being treated by the electrode member(s) without itself absorbing heat.

In some embodiments, the ablation catheter 3120 includes a plurality of heat transfer members 3145 (e.g., heat diverter trays or members). For example, according to some embodiments, such additional heat transfer members may be positioned proximal to the heat transfer member 3145 and may include one or more fins, pins, and/or other members in thermal communication with the irrigation conduit 3150 extending through the interior of the ablation catheter. Thus, when utilizing the heat transfer member 3145 positioned in contact with the electrode members 3130, 3135, heat may be transferred from the other energy delivery members or electrodes, adjacent portions of the catheter, and/or adjacent tissue of the subject via these additional heat transfer members (e.g., thermal shunt members) and thus removed or dissipated. In other embodiments, the ablation catheter does not include any heat transfer member.

In some embodiments, for any of the ablation catheters disclosed herein, or variations thereof, one or more heat transfer members (e.g., thermal shunt members) that facilitate heat transfer to a heat exchange chamber (e.g., irrigation conduit) of the catheter are in direct contact with the electrode member and/or the heat exchange chamber. However, in other embodiments, the one or more heat transfer members do not contact the electrode member and/or the irrigation conduit. Thus, in such embodiments, the heat transfer member is in thermal communication with the electrode member or individual electrodes and/or the irrigation conduit, but is not in physical contact with such components. For example, in some embodiments, one or more intermediate components, layers, coatings, and/or other members are positioned between a heat transfer member (e.g., a thermal shunt member) and an electrode (or other ablation member) and/or irrigation conduit. In some embodiments, no flushing is used at all due to the efficiency of the heat transfer member. For example, where multiple levels or stages of heat transfer are used, heat may be dissipated over a larger area along the length of the ablation catheter. Additional details regarding the function and features of the heat transfer member (e.g., thermal shunt member) are provided herein. Features of the various embodiments disclosed herein (e.g., features of the thermal shunt system and components) may be implemented in any of the embodiments of the medical devices disclosed herein (e.g., ablation catheters).

As best shown in fig. 18C, 18E and 18F, the temperature measurement device 3125 is thermally insulated from the electrode members 3130, 3135 by a tube 3160 and/or an air gap. In some embodiments, the tube 3160 extends along the entire length of (and in some embodiments beyond) the electrode members 3130, 3135, such that no portion of the electrode members is in contact with the temperature measurement device 3125, thereby isolating the temperature measurement from the thermal effects of the electrode members. The outer tube 3160 of the temperature measurement device may comprise an insulating material having a low thermal conductivity (e.g., polyimide, ultem, polystyrene, or other material having a thermal conductivity of less than about 0.5W/m/° c). The tube 3160 is substantially filled with air or another gas having a very low thermal conductivity. The distal tip 3165 (e.g., the portion of the temperature-sensing device) of the temperature-measuring device may include an epoxy polymer covering or housing filled with a highly conductive medium (e.g., nanotubes composed of graphene, carbon, or other high thermal conductive material or film) to increase thermal conduction at the head of the temperature-measuring device where the temperature is measured. In some embodiments, the distal tip 3165 includes an epoxy cover having a thermal conductivity of at least 1.0W/m/° K. The epoxy may include a metal paste (paste) (e.g., comprising alumina) to provide enhanced thermal conductivity. In some embodiments, the distal tip 3165 or cover creates an isothermal condition around the temperature measurement device 3125 that approximates the actual temperature of the tissue in contact with the temperature measurement device. Because the distal tip 3165 of each temperature measurement device 3125 is isolated from thermally conductive contact with the electrode member(s), it maintains this isothermal condition, thereby preventing or reducing the likelihood of dissipation of the thermal mass of the electrode member(s). Fig. 18E and 18F illustrate perspective and cross-sectional views, respectively, of a distal portion of an ablation catheter showing isolation of a distal temperature measurement device from an electrode tip, according to one embodiment. As shown, the distal temperature measurement device 3125A may be surrounded by an air gap or pocket 3162 and/or insulation. The outer tube 3160 can include an insulating sheath extending along the entire length of the distal electrode member 3130 or at least a portion of the length. The sheath may extend beyond the distal electrode member 3130 or even to the proximal electrode member 3135 or beyond the proximal electrode member 3135.

The electrode member(s) (e.g., distal electrode member 3130) may be electrically coupled to an energy delivery module (e.g., energy delivery module 40 of fig. 1). As discussed herein, energy delivery module 40 may include one or more components or features, such as, for example, an energy generation device 42 configured to selectively energize and/or otherwise activate energy delivery members (e.g., RF electrodes), one or more input/output devices or components, one or more processors (e.g., one or more processing devices or control units) configured to adjust one or more aspects of the therapy system, memory, and/or the like. Further, such modules may be configured to operate manually or automatically, as desired or required.

The temperature measurement device 3125 may be coupled to one or more conductors (e.g., wires, cables, etc.) extending along the length of the ablation catheter 3120 and communicating temperature signals back to at least one processing device (e.g., the processor of fig. 1) for determining a temperature measurement of each of the temperature measurement devices, as will be discussed in detail below.

According to some embodiments, the relative lengths of the different electrodes or electrode members 3130, 3135 may vary. For example, the length of the proximal electrode member 3135 may be between 1 and 20 times (1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-16, 16-17, 17-18, 18-19, 19-20, values between the above ranges, etc.) the length of the distal electrode member 3130, as desired or required. In still other embodiments, the distal electrode member 3130 and the proximal electrode member 3135 are approximately equal in length. In some embodiments, the distal electrode member 3130 is longer (e.g., 1 to 20 times longer, such as, for example, 1-2, 2-3, 3-4, 4-5, 5-6\6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-16, 16-17, 17-18, 18-19, 19-20, values between the aforementioned ranges, etc.) than the proximal electrode member 3135.

In some embodiments, the distal electrode member 3130 is 0.5mm in length. In other embodiments, the distal electrode member 3130 has a length between 0.1mm and 1mm (e.g., 0.1-0.2, 0.2-0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6, 0.6-0.7, 0-0.8, 0.7-0.8, 0.8-0.9, 0.9-1mm, values between the aforementioned ranges, etc.). In other embodiments, the distal electrode member 3130 is greater than 1mm in length, as desired or required. In some embodiments, the proximal electrode member 3135 has a length of 2 to 4mm (e.g., 2-2.5, 2.5-3, 3-3.5, 3.5-4mm, lengths between the foregoing, etc.). However, in other embodiments, the proximal electrode member 3135 is greater than 4mm (e.g., 4-5, 5-6, 6-7, 7-8, 8-9, 9-10mm, greater than 10mm, etc.) or less than 1mm (e.g., 0.1-0.5, 0.5-1, 1-1.5, 1.5-2mm, lengths between the aforementioned ranges, etc.), as desired or required. In embodiments where the split electrode is on the catheter shaft, the length of the electrode member may be 1 to 5mm (e.g., 1-2, 2-3, 3-4, 4-5mm, lengths in between, etc.). However, in other embodiments, the electrode member may be longer than 5mm (e.g., 5-6, 6-7, 7-8, 8-9, 9-10, 10-15, 15-20mm, lengths in between the foregoing, lengths greater than 20mm, etc.), as desired or required.

The electrode member(s) may be excited using one or more conductors (e.g., wires, cables, etc.). For example, in some arrangements, the exterior of the irrigation conduit 3150 includes and/or is otherwise coated with one or more electrically conductive materials (e.g., copper, other metals, etc.). Accordingly, conductors may be placed in contact with such conductive surfaces or portions of the irrigation conduit 3150 to electrically couple the electrode member(s) to the energy delivery module. However, one or more other devices and/or methods of placing the electrode member(s) in electrical communication with the energy delivery module may be used. For example, one or more wires, cables, and/or other conductors may be coupled directly or indirectly to the electrode member(s) without the use of irrigation tubing.

The use of a compound tip (e.g., a split tip) design may allow a user to simultaneously ablate or otherwise thermally treat a target tissue and map (e.g., using high resolution mapping) in a single configuration. Thus, such a system may advantageously allow for accurate high resolution mapping during a procedure (e.g., to confirm that a desired level of treatment is occurring). In some embodiments, a composite tip (e.g., split tip) design comprising two electrode members or electrode portions 3130, 3135 may be used to record high-resolution bipolar electrograms. For this purpose, two electrodes or electrode portions may be connected to the input of an Electrophysiological (EP) recorder. In some embodiments, a relatively small separation distance (e.g., gap G) between the electrode members or electrode portions 3130, 3135 enables high resolution mapping. According to some arrangements, the composite tip electrode embodiments disclosed herein are configured to provide localized high resolution electrograms (e.g., electrograms with highly increased local specificity due to the separation of the two electrode portions and the high thermal diffusivity of the material of the separator, such as industrial diamond). The increased local specificity may make the electrogram more responsive to electrophysiological changes in the underlying cardiac tissue or other tissue, such that the effect of RF energy delivery on cardiac tissue or other tissue may be seen more quickly and accurately on high resolution electrograms.

In some embodiments, the medical device (e.g., catheter) 3120 may include three or more electrode members or electrode portions (e.g., separated by gaps), as desired or required. According to some embodiments, regardless of how many electrodes or electrode portions are positioned along the catheter tip, the electrode members or electrode portions 3130, 3135 are radiofrequency electrodes and comprise one or more metals, such as, for example, stainless steel, platinum-iridium, gold-plated alloys, and the like.

According to some embodiments, the electrode members or electrode portions 3130, 3135 are spaced apart (e.g., longitudinally or axially) from each other using a gap (e.g., an electrically insulating gap) 3131. In some embodiments, the length of the gap 3131 (or the separation distance between adjacent electrode members or electrode portions) is 0.5 mm. In other embodiments, the gap or separation distance is greater than or less than 0.5mm, such as, for example, 0.1-1mm (e.g., 0.1-0.2, 0.2-0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6, 0.6-0.7, 0.7-0.8, 0.8-0.9, 0.9-1.0mm, values between the foregoing ranges, less than 0.1mm, greater than 1mm, etc.), as desired or required.

According to some embodiments, the separator is located within a gap 3131 between adjacent electrode members or electrode portions 3130, 3135. The separator may comprise one or more electrically insulating materials such as, for example, teflon, Polyetheretherketone (PEEK), diamond, epoxy, polyetherimide resin (e.g., ULTEMTM), ceramic materials, polyimide, and the like. As shown in fig. 18A-18C and 19A-19C, the divider may include a portion of heat transfer member 3145 that extends within gap 3131.

As described above with respect to the gap 3131 separating adjacent electrode members or electrode portions, the length of the insulating separator may be 0.5 mm. In other embodiments, the length of the separator can be greater than or less than 0.5mm (e.g., 0.1-0.2, 0.2-0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6, 0.6-0.7, 0.7-0.8, 0.8-0.9, 0.9-1.0mm, values between the foregoing ranges, less than 0.1mm, greater than 1mm, etc.), as desired or required.

According to some embodiments, to successfully ablate or otherwise heat or treat target tissue of a subject with a split-tip electrode design (such as the split-tip electrode designs depicted in fig. 18A-18C and 19A-19C, the two electrode members or electrode portions 3130, 3135 are electrically coupled to one another at RF frequencies). Thus, two electrode members or electrode portions may advantageously be used as a single longer electrode at RF frequencies. Additional details regarding the function and features of the composite (e.g., split tip) electrode design are provided herein.

Fig. 19A-19C illustrate a distal portion of a closed irrigated ablation catheter 3220 having a plurality of temperature measurement devices 3225 according to various embodiments. The embodiment of the ablation catheter 3220A of fig. 19A includes a dome-shaped tip electrode member 3230 similar to the ablation catheter 3120A of fig. 18A. The embodiment of the ablation catheter 3220B of fig. 19B and 19C includes a flat tip electrode member similar to the ablation catheter 3120B of fig. 18B and 18C. The ablation catheters 3220A and 3220B include similar components and features as described above in connection with fig. 18A-18C. For example, temperature measurement device 3225 corresponds to temperature measurement device 3125, electrode members 3230, 3235 correspond to electrode members 3130, 3135, heat transfer member 3245 corresponds to heat transfer member 3145, and irrigation conduit 3250 corresponds to irrigation conduit 3150. Accordingly, these features will not be described again in connection with fig. 19A-19C. The ablation catheter 3220 does not include an irrigation port because it functions as a closed irrigation device.

The ablation catheter 3220 includes two lumens 3265 within the irrigation tube 3250, an inlet lumen (e.g., fluid delivery channel) 3265A and an outlet lumen (e.g., return channel) 3265B. As shown in the cross-sectional view of fig. 19C, the outlet of the inlet lumen 3265A and the inlet of the outlet lumen 3265B terminate at spaced apart locations within the flush tube 3250. The outlet of the inlet lumen 3265A terminates within the distal electrode member 3230 or near the proximal end surface of the distal electrode member 3230. The inlet of the outlet lumen terminates proximal of the proximal end of the proximal electrode member 3235. The offset spacing of the distal end of the cavity 3265 advantageously causes turbulent, swirling, or other circulating fluid movement or path within the irrigation conduit, thereby promoting enhanced cooling by circulating fluid to constantly refresh or exchange fluid in contact with the heat transfer member 3245 and/or the electrode member.

According to several embodiments, an ablation catheter with multiple temperature measurement devices does not require a composite (e.g., split tip) electrode design and/or heat transfer member. Fig. 19D shows a perspective view of the distal portion of an open irrigated ablation catheter 3320 that does not include a composite electrode design or heat transfer member. The ablation catheter 3320 includes a first (e.g., distal) plurality of temperature-measurement devices 3325A and a second (e.g., proximal) plurality of temperature-measurement devices 3325B. The temperature measurement device 3325 includes similar features, attributes, materials, elements, and functions as the temperature measurement devices 3125, 3225 (fig. 18A-19C). The ablation catheter 3320 may include or consist of a single integral tip electrode 3330. The tip electrodes 3330 may include holes, slots, grooves, bores, or openings for the temperature measurement device 3325 at their respective spaced apart locations. As shown in fig. 19D, the proximal temperature measurement device 3325B is positioned distally, but adjacent to the proximal edge of the tip electrode 3330. The proximal temperature measurement device 3325B may be positioned within 1mm of the proximal edge (e.g., within 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1mm proximal or distal of the proximal edge, depending on the length of the tip electrode 3330). In other embodiments, the proximal temperature measurement device 3325B is positioned proximal to the proximal edge of the tip electrode 3330 and within the same distance as the distal placement described above. In various embodiments, the temperature measurement device is positioned at or near the proximal and distal edges of the electrode or composite (e.g., split tip) electrode assembly, as these locations tend to be hottest. Based on manufacturing tolerances, these temperature measurement devices may be embedded at the proximal or distal edge of the tip electrode 3330. Thus, positioning the temperature measurement device at or near these locations may facilitate preventing or reducing the likelihood of overheating, charring, or thrombosis. In addition, such temperature measurement device placement provides the ability to monitor tissue temperature during irrigated ablation.

In some embodiments, an epoxy including a conductive medium (such as graphene or other carbon nanotubes) may be incorporated into the distal tube (typically made of plastic) of the ablation catheter shaft, and the distal tube of the ablation catheter itself may serve as the heat transfer. In some embodiments, the addition of a conductive epoxy may increase the thermal conductivity of the distal tube by a factor of 2-3 or more. These conductive tube features and other features described in connection with fig. 19D may also be used in connection with the ablation catheters 3120, 3220.

In certain embodiments, a thermal shunt member included along the distal end of a catheter or other medical device is maintained inside such a catheter or medical device. In some embodiments, this is achieved by providing one or more layers or coatings, partially or completely, along the exterior or outer surface of the thermal shunt portion. Such a layer or coating may be electrically insulating. Further, in some arrangements, such layers or coatings may be electrically and thermally insulating, as desired or required. However, in other embodiments, the layers or coatings may be electrically insulating but not thermally insulating. As used herein, electrically insulating means having a resistivity in excess of 1000 Ω · cm. Further, as used herein, thermally conductive means having a thermal conductivity greater than 0.5W/cm K at 20 ℃.

Embodiments that include such layers or coatings along one or more shunt portions or members (e.g., to maintain the shunt portions or members along the interior of a catheter or other medical device) may also provide several benefits and advantages for the resulting devices and systems and the resulting methods of use and treatment. For example, the coating(s) or layer(s) may: (i) improving the conductive cooling effect of the irrigation fluid (which in turn may allow the irrigation flow rate and the final amount of fluid infused into the patient to be significantly reduced; in some embodiments, a lower irrigation rate results in better temperature measurement accuracy because the temperature sensor is less likely to be overwhelmed by the irrigation fluid), (ii) improving manufacturing and operational aspects of the catheter or other medical device (e.g., the effects of the shallow surface layer of the thermal shunt portion becoming conductive due to the cutting process may be compensated for, thereby providing more flexibility for manufacturing of the thermal shunt portion while maintaining a consistent outer surface of the catheter or other medical device), (iii) providing additional protection against the formation of hot spots or localized heating at or near the proximal end of the proximal electrode during use and/or the like.

According to some embodiments, as discussed in more detail herein, the primary thermal shunt mechanism of a catheter including a thermal shunt network occurs via a cooling effect of an irrigation fluid flowing within the interior of the catheter or other medical device (e.g., via conductive heat transfer to the irrigation fluid). In some embodiments, the conductive cooling capacity of a room temperature (e.g., about 27 ℃) irrigation fluid flowing through a thermal shunt network (e.g., a diamond or other thermal shunt network in thermal contact with an irrigation channel extending through a distal portion of a catheter or other medical instrument) is greater than the conductive cooling capacity of convective cooling provided by blood flow on the outer surface of the thermal shunt network. This occurs, in part, because the temperature of the blood (e.g., which is about 37℃.) is significantly higher than the temperature of the flush fluid. Again, this may occur because the rate of heat transfer by the blood may not be as high as that provided by the irrigation fluid (e.g., the blood flow rate is low in certain regions of the heart (e.g., in various regions of the atrium or under the valve leaflets)). Thus, by thermally isolating the outer surface of the thermal shunt portion or member (e.g., diamond), the conductive cooling effect of the flushing fluid (e.g., via heat transfer to the flushing fluid) may be enhanced. In some embodiments, this may help to significantly reduce the irrigation flow rate and the final amount of fluid infused into the patient. A low irrigation flow rate may result in improved temperature sensing accuracy because the temperature sensor associated with the electrode is less likely to be flooded by irrigation fluid (e.g., the amount of irrigation fluid required is reduced).

In some embodiments, when an industrial diamond or other thermal shunt member or portion is cut in preparation for incorporation into a catheter, the resulting superficial portion (e.g., an outer surface or layer, a portion immediately adjacent (e.g., within 0.1 mm) of the outer surface or layer, etc.) may become at least partially conductive (e.g., particularly as compared to the electrical properties of the uncut diamond or other thermal shunt material). For example, in some arrangements, the electrical conductivity of the cut or otherwise prepared industrial diamond or other thermal shunt material may be increased by 1% to 100% (e.g., 1-5, 5-10, 10-20, 20-50, 50-100, 25-75, 20-100%, values and ranges therebetween) or by more than 100% (e.g., 100-. As a result, in some embodiments, if such a superficial portion (e.g., a surface, layer, or region) is exposed to the exterior of a catheter or medical instrument, the superficial portion may present problems during operation of the catheter or other medical instrument into which the superficial portion is incorporated. For example, the electrical conductivity of a superficial portion (e.g., surface, layer, or region) of diamond or other thermal shunt material may cause an electrical short of two electrodes (or electrode portions) included in a catheter or medical instrument. Thus, as discussed herein, providing a non-conductive layer or coating along the outer surface of certain thermal shunt portions may provide operational benefits to the manufacture and performance of the resulting catheter or medical device. In turn, this may lead to out-of-specification performance of system features such as tissue contact sensing, impedance measurement, energy delivery, and the like. Thus, in some embodiments, all or a majority of the thermal shunt member or portions included in the catheter or other medical device are not exposed to the exterior of the catheter or medical device. In some configurations, none of the diamond or other thermal shunt network is exposed to the exterior of the catheter or other medical device. In other embodiments, 70-100% (e.g., 70-75, 75-80, 80-85, 85-90, 90-95, 95-100%, percentages between the aforementioned ranges, etc.), 50-70%, or less than 50% of the outer surface area of the thermal shunt is covered or coated with a layer or coating.

As shown in fig. 20, one or more thermal insulation layers or coatings 6070 may be placed around the exterior of the thermal shunt portion 6050 exposed to the exterior of the catheter or other medical device 6000. Layer or coating 6070 can include one or more thermally insulating materials (e.g., thermoset polymers, polyimides, PEEK, polyesters, polyethylene, polyurethane, nylon elastomer (pebax), nylon, hydrated polymers, other polymers, etc.). In some embodiments, such materials have a thermal conductivity of less than 0.001W/cm K (e.g., 0.0001-0.001, 0.001-0.0025, 0.0025-0.001W/cm K, less than 0.0001W/cm K, etc.). Such a layer or coating 6070 may have a thickness of about 50 μm (2 mils) or less. For example, in some embodiments, the thickness of layer or coating 6070 is 1-50 μm (e.g., 1-5, 5-10, 10-20, 20-30, 30-40, 40-50 μm, values between the foregoing, etc.) or less than 1 μm (e.g., 0.01-0.5, 0.5-0.75, 0.75-1 μm, values between the foregoing ranges, etc.). However, in other embodiments, the thickness of the layer or coating 6070 is greater than 50 μm, such as, for example, 50-100 (e.g., 50-55, 55-60, 60-65, 65-70, 70-75, 75-80, 80-85, 85-90, 90-95, 95-100, values between the foregoing ranges), 100-.

In any embodiment in which the thermal shunt portion comprises a coating or layer, such coating or layer may be a single or unitary coating or layer. However, in other embodiments, more than one layer or coating may be positioned along the exterior of one or more thermal shunt members or portions, as desired or required. For example, in some arrangements, coating or layer 6070 can include two or more (e.g., 2, 3, 4, 5, greater than 5) separate coatings or layers. These separate coatings or layers may be positioned along the conduit 6000 individually or as a single member, as desired or required by the particular technique used to secure such coatings or layers along the desired surface of the thermal shunt member or portion.

A coating or layer 6070 may be positioned along the exterior of the thermal shunt portion using a variety of techniques such as, for example, glue or other adhesives, press-fit methods, dip molding, other molding techniques, and/or the like. As described above, depending on the particular method and/or technique used, the coating or layer 6070 can include two or more separate coatings or layers that can be positioned along the thermal shunt member or portion separately or as a single coating or layer, as desired or required. Further, a coating or layer 6070 may be positioned directly or indirectly along the thermal shunt member. For example, in some embodiments, coating or layer 6070 directly contacts and is directly secured to an adjacent surface of a thermal shunt member or portion. However, in other embodiments, coating or layer 6070 does not directly contact or be directly affixed to the adjacent surface of the thermal shunt member or portion. In such an arrangement, for example, one or more intermediate layers, coatings, structures (e.g., air gaps), or other components can be positioned between the thermal shunt component or portion and the coating or layer 6070.

As described herein, various embodiments of a catheter or other medical device may include an irrigation channel responsible for a majority of the heat transfer away from the electrode(s) or electrode portion(s) located along the distal end of the catheter or medical device. In embodiments including diamond and/or other thermal shunt materials and/or constructions, heat may be transferred to the flushing fluid (e.g., flowing through the flushing channel) via the thermal shunt network. As discussed in more detail herein, such a thermal shunt network facilitates heat transfer away from a source (e.g., an electrode) while retaining no or little heat itself. Relatedly, heat is transferred away from potential hot spots formed at the edges of the electrodes and shunted into the irrigation channels through a thermal shunt network. Heat can be advantageously released from the irrigation channel into the blood stream via convective cooling and dissipated. In a closed irrigation system, heat can be removed from the system without draining irrigation fluid into the subject. The layer(s) and/or coating(s) discussed above may be incorporated into any of the catheter or other medical device devices or systems disclosed herein or equivalents thereof.

Fig. 21A and 21B schematically illustrate a distal portion of an open irrigated ablation catheter 3420 in perpendicular and parallel contact with tissue, respectively, and the creation of thermal damage by delivering energy to the tissue using the ablation catheter 3420. According to several embodiments, an ablation catheter having a plurality of temperature measurement devices described herein advantageously facilitates determination of, inter alia: an orientation of the distal tip of the ablation catheter relative to the tissue (e.g., electrode-tissue orientation), an estimated peak temperature within the thermal injury, and/or a location of a peak temperature zone within the thermal injury.

As described above, the temperature measurement device 3425 may send or transmit a signal to at least one processing device (e.g., the processor 46 of fig. 1). The processing device may be programmed to execute instructions stored on one or more computer-readable storage media to determine a temperature measurement for each of the temperature measurement devices 3425, and to compare the determined temperature measurements to each other to determine an orientation of the distal tip of the ablation catheter relative to the tissue (e.g., an electrode-tissue orientation) based at least in part on the comparison. Additional details regarding this comparison are provided below in connection with the discussion of FIGS. 23D-23F. The processing device may select (e.g., determine) an orientation from one of three orientations (e.g., parallel, perpendicular, or angled (e.g., tilted or oblique) orientations).

For example, differences in temperature measurement curves or spread of values between the proximal and distal temperature measurement devices may be used to determine orientation. As one example, if the temperature measurements received from the distal temperature measurement device are all larger (e.g., hotter) than the temperature measurements received from the proximal temperature measurement device, the processor may determine that the orientation is vertical. The processor may determine that the orientations are parallel if the temperature measurements received from the at least one proximal temperature measurement device and the at least one corresponding distal temperature measurement device are similar.

As other examples, for embodiments using three temperature measurement devices, the processing device may determine that the orientations are parallel if two of the three proximal temperature measurement devices generate much lower (and substantially equal) temperature measurements than the third proximal temperature measurement device. For embodiments using three temperature measurement devices, if the temperature measurement received from the first proximal temperature measurement device is significantly greater than the temperature measurement received from the second proximal temperature measurement device, and if the temperature measurement received from the second proximal temperature measurement device is significantly greater than the temperature measurement received from the third proximal temperature measurement device, the processing device may determine that the orientation is neither parallel nor perpendicular, but is tilted by an angle (e.g., a tilted orientation). Additional details regarding this orientation determination are provided below in connection with the discussion of FIGS. 23C-23E. In some embodiments, the orientation may be confirmed using fluoroscopic imaging, ICE imaging, or other imaging methods or techniques. The orientation may also be determined using a tissue mapping system, such as a three-dimensional cardiac mapping system.

In some embodiments, the determined orientation may be output on a display (e.g., a graphical user interface) to be visible to a user (e.g., a clinical professional). The output may include one or more graphical images indicating the orientation and/or alphanumeric information (e.g., letters, words, phrases, or numbers) indicating the orientation. Additional details regarding the output will be described in connection with FIGS. 23F-1, 23F-2, and 23F-3. The processing device may apply a correction factor to the temperature measurements received from the temperature measurement device based on the determined orientation in order to generate a more accurate estimate of the peak temperature of the thermal damage. For example, if a vertical orientation is determined, a correction factor or function corresponding to the distal temperature measurement device may be applied to determine the estimated peak temperature.

In some embodiments, a processing device may include a temperature acquisition module and a temperature processing module. The temperature acquisition module may be configured to receive an input temperature signal (e.g., an analog signal) generated by each of the temperature measurement devices. The input signal may be received continuously at a prescribed time period or point in time. The temperature acquisition module may be configured to convert the analog signal to a digital signal. The temperature processing module may receive the digital signals output from the temperature acquisition module and apply a correction factor or function to them to estimate the hottest tissue temperature, peak temperature, or peak temperature in the thermal lesions created in the vicinity of the electrode or other energy delivery member(s). The temperature processing module may calculate a composite temperature from a temperature measurement device (e.g., a thermocouple) based on the following equation:

Tcomp(t)＝k(t)*f(TC1(t),TC2(t),…,TCn(t))；

where Tcomp is the composite temperature, k is a function of k or a correction or adjustment function, and f is a function of the thermocouple reading Tci (i ═ 1 to n). The k function may comprise a function that varies over time or a constant value. For example, the k function may be defined as follows:

k(t)＝e^(-t/τ)+k_{finally, the product is processed}*(1-e^(-t/τ))；

Where τ is a time constant representing the tissue time constant, and k_{Finally, the product is processed}Is the final value of k according to a correction factor or function, such as described below in connection with fig. 22A.

As described above, the temperature processing module may also be configured to determine an orientation of the distal tip of the medical instrument relative to the tissue. The processing device may further include an output module and a feedback/monitoring module. The output module may be configured to generate output for display on a display, such as the various outputs described herein. The feedback/monitoring module may be configured to compare the measured temperature value to a predetermined setpoint temperature or maximum temperature and initiate an action (e.g., an alarm to cause a user to adjust power or other ablation parameters or automatically reduce the power level or terminate energy delivery (which may be temporary until the temperature falls below the setpoint temperature)). In various embodiments, the set point or maximum temperature is between 50 and 90 degrees celsius (e.g., 50, 55, 60, 65, 70, 75, 80, 85 degrees celsius). In some embodiments, the algorithm identifies which temperature measurement device (e.g., thermocouple) is currently recording the highest temperature and selects that thermocouple to control the power delivery required to reach and maintain the set point temperature or other target temperature. When the tip electrode is moved relative to the tissue and a different temperature measurement device makes more or less contact with the tissue, the processor or processing device may automatically select whichever temperature measurement device is reading the highest temperature to control power delivery.

According to several embodiments, there is a proportional relationship between the temperature gradient determined by the temperature measurement device and the peak temperature of the lesion. From this relationship, a function or correction factor may be generated or applied based on a numerical model (e.g., finite element method modeling techniques) and/or measurements stored in a look-up table to adjust or correct for the thermal gradient identified by the temperature measurement device to determine the peak temperature. The thermal gradient of the open-irrigated lesion causes the lesion surface to cool slightly and the peak temperature zone to be deeper. The temperature measuring device can be embedded in the tissue, the further away the embedding, the more accurate the proportional relationship between the thermal gradient and the peak temperature determined by the temperature measuring device. For example, the thermal gradient may be estimated as:

ΔT/Δd＝(T_{distal side}–T_{Near side}) In other words, the temperature spatial gradient is estimated as the temperature difference between the distal and proximal temperature measuring devices divided by the distance between the distal and proximal temperature measuring devices. The peak tissue temperature (where the peak may be a mountain or valley) may then be estimated as:

T_{peak value}＝ΔT/Δd*T_{Peak _ far side}+T_{Distal side}

The processing device may also determine an estimated location of a peak temperature zone of the thermal damage based at least in part on the determined orientation and/or temperature measurements. For example, for a vertical orientation, the peak temperature location may be determined to be horizontally centered in the thermal injury. In some embodiments, the processor may be configured to output information indicative of the location of the peak temperature on a display (e.g., a graphical user interface). The information may include textual information and/or one or more graphical images.

FIG. 22A is a graph illustrating a temperature measurement obtained from a temperature measurement device that may be used to determine a peak temperature by applying one or more analytical correction factors or functions to the temperature measurement (e.g., using numerical modeling approximations or look-up tables). As shown in fig. 22A, a single correction factor or function (k) may be applied to each of the distal temperature measurement devices to determine the peak temperature. In some embodiments, depending on the determined orientation or on a comparison of temperature measurements obtained by the temperature measurement devices, different correction factors or functions may be applied to each individual temperature measurement device or subset of groups of temperature measurement devices, thereby providing increased accuracy of peak temperature and peak temperature zone locations. The increased accuracy of the peak temperature and the location of the peak temperature zone may advantageously result in a safer and more reliable ablation procedure, since ablation parameters may be adjusted based on feedback received by the processing unit from the temperature measurement device. According to several embodiments, the peak temperature at a depth below the tissue surface can be accurately estimated without the need for a microwave radiometer. Referring to fig. 22A, the peak tissue temperature may be estimated as follows:

T_{peak value}(t)＝e^(-t/τ)+k*(1-e^(-t/τ))*max(TCi(t))；

Where i covers the range of the temperature measuring device, where max (tci (t)) represents the maximum temperature reading of the temperature measuring device at time t. For example, fig. 22B shows an implementation of the above equation. Trace 1 shows the estimated peak tissue temperature (T) at a constant k value of 1.8 and a τ value of 1_{Peak value}) While traces 2, 3 and 4 show the actual tissue temperatures measured at 1mm, 3mm and 5mm from the tissue surface, respectively, using a tissue embedded infrared probe. As can be seen, the estimated peak tissue temperature (T) of trace 1_{Peak value}) The actual peak tissue temperature measured at a depth of 1mm (trace 2) is well tracked.

In another embodiment, a predictive model-based approach using a bio-thermal equation may be utilized to estimate the peak tissue temperature. A recursive algorithm for determining the temperature T at a single point in a volume at a point in time n during a treatment (e.g., RF ablation) can be defined as follows:

wherein T is_nIs the current temperature, T_n-1Is the previous temperature, T is time, ρ is tissue density, C is specific heat of the tissue, T_aIs the core arterial temperature, W_eIs the effective perfusion rate, and P · N provides an estimate of the volumetric power deposited in the tissue. The above equations may be formulated at various spatial locations, including the temperature measurement device location(s) and the location of the peak temperature (e.g., hot spot). By utilizing this model at different locations, and calibrating to determine model parameters, mapping techniques can be used to determine the parameters fromThe measurement data of other spatial locations to predict the temperature at one spatial location.

In some embodiments, the processing device is configured to output the peak temperature or other output indicative of the peak temperature on a display (e.g., a graphical user interface). The output may include alphanumeric information (e.g., temperature in degrees), one or more graphical images, and/or color indications. In some embodiments, the processor may generate an output configured to terminate energy delivery if the determined peak temperature is above a threshold or maximum temperature. The output may include a signal configured to cause automatic termination of energy delivery, or may include an alarm (audible and/or visual) to cause a user to manually terminate energy delivery.

In various embodiments, ablation parameters may be adjusted based on temperature measurements received from a temperature measurement device. Ablation parameters may include duration of ablation, power modulation, contact force, target or set point temperature, maximum temperature, among others. For example, processor 46 (fig. 1) may be configured to send control signals to energy delivery module 40 based on temperature measurements received from a plurality of distributed temperature measurement devices (as well as other measurements or estimates derived or otherwise determined therefrom).

In one embodiment, energy delivery module 40 (fig. 1) may be set to operate in a temperature control mode in which rf energy is delivered at a certain power level and a maximum temperature that cannot be exceeded is identified. Each of the temperature measurement devices may be monitored (simultaneously or via a handover query) on a periodic or continuous basis. If the maximum temperature is reached or exceeded (as determined by temperature measurements received from any of the temperature measurement devices of the ablation catheter described herein), a control signal may be sent to the energy delivery module to adjust ablation parameters (e.g., reduce power levels) to reduce the temperature or terminate energy delivery (temporarily or otherwise) until the temperature falls below the maximum temperature. This adjustment may be achieved, for example, by a proportional integral derivative controller (PID controller) of the energy delivery module 40. In another embodiment, energy delivery module 40 may be set to operate in a power control mode in which a certain level of power is continuously applied and the temperature measurements received from each of the temperature measurement devices are monitored to ensure that the maximum temperature is not exceeded. In some embodiments, the temperature control mode includes specifying a set point temperature (e.g., 70 degrees celsius, 75 degrees celsius, 80 degrees celsius) and then adjusting the power or other parameter to maintain the temperature at, below, or near the set point temperature as determined from the temperature measurements received from each of the temperature measurement devices. When the tip electrode is moved relative to the tissue and a different temperature measurement device makes more or less contact with the tissue, the processor or processing device of the energy delivery module may automatically select whichever temperature measurement device is reading the highest temperature to control power delivery.

Table 1 below shows examples of ablation parameters used in various test ablation procedures using embodiments of the ablation catheter described herein.

TABLE 1

As can be seen from the data in table 1, by adjusting the power, the maximum tissue temperature and the lesion size remain relatively constant with or without irrigation and/or with or without substantial blood flow. A multivariable or multiple temperature measurement device system according to embodiments of the present invention ensures proper tissue ablation at different electrode-tissue orientations. As described above, the electrode-tissue orientation may be determined based on readings from a plurality of distributed temperature measurement devices. If both the proximal and distal temperatures become significant, the electrode orientation may be estimated or indicated as being parallel to the tissue. Similarly, when the distal temperature is significant, then the electrode orientation may be inferred, estimated, and/or indicated as perpendicular to the tissue. The combination of the proximal and distal significant temperatures may provide an indication of the tilted electrode orientation. Fig. 23A shows a graph of temperature data from a plurality of temperature measurement devices (e.g., thermocouples) indicating a vertical orientation, and fig. 23B shows a graph of temperature data from a plurality of temperature measurement devices (e.g., thermocouples) indicating an oblique orientation.

According to several embodiments, a therapy system includes a medical device (e.g., an ablation catheter), at least one processor, and an energy source (e.g., an ablation source, such as a radio frequency generator). The medical device includes an elongate body having a proximal end and a distal end, an energy delivery member (e.g., a high resolution unitized electrode assembly including a proximal electrode portion and a distal electrode portion spaced apart from the proximal electrode portion) positioned along the distal end of the elongate body, and a plurality of distributed temperature measurement devices (e.g., thermocouples or other temperature sensors) carried by or positioned along or within a portion of the elongate body or energy delivery member. In some embodiments, a distributed temperature measurement device comprises: a plurality of distal temperature measurement devices located at a distal end of the elongate body (e.g., along a distal surface of the energy delivery member), and a plurality of proximal temperature measurement devices located along the elongate body and spaced proximally of the plurality of distal temperature measurement devices, as described and illustrated in connection with certain embodiments of the ablation catheter herein. In one embodiment, the plurality of proximal temperature measurement devices consists of three co-planar temperature measurement devices equally spaced around the circumference of the elongate body, and the plurality of distal temperature measurement devices consists of three co-planar temperature measurement devices symmetrically or equally spaced around a central longitudinal axis extending through the distal end of the elongate body. The energy delivery member may be configured to contact tissue of a subject and deliver energy generated by the energy source to the tissue. In some embodiments, the energy is sufficient to at least partially ablate the tissue. The energy source of embodiments of the system may be configured to provide energy to the energy delivery member through one or more conductors (e.g., wires, cables, etc.) extending from the energy source to the energy delivery member. In several embodiments, the energy is radio frequency energy.

The at least one processor of an embodiment of a treatment system (e.g., an ablation system) may be programmed or otherwise configured (e.g., by executing instructions stored on a non-transitory computer-readable storage medium) to receive signals indicative of temperature from each of the temperature measurement devices and determine an orientation or alignment of the distal end (e.g., electrode-tissue orientation) of the elongate body of the ablation catheter relative to tissue (e.g., an orientation or alignment of the outer distal surface of the electrode or other energy delivery member with the target surface) based on the received signals. According to several embodiments, multiple separate processing devices are used in parallel to perform portions of the processes described herein simultaneously in order to increase processing speed. Each of the separate processing devices may be controlled by a main processing device or control unit that receives outputs from each of the separate processing devices.

According to several embodiments, determining the orientation of the proximity treatment site facilitates increased likelihood or confirmation of treatment efficacy (e.g., gapless continuous lesion formation). For example, if the ablation catheter is determined to be in a vertical orientation at two adjacent ablation sites, the likelihood that the lesion profiles do not overlap may increase, and the clinical professional may decide to perform another ablation between the two adjacent ablation sites to increase the likelihood of gapless continuous lesion formation. According to several embodiments, the determination of the orientation is performed during the delivery of energy (e.g. radiofrequency energy). Where the determination of orientation is performed during energy delivery, it may be particularly advantageous to determine the orientation early in the energy delivery process (e.g., within a few seconds after initiation of energy delivery) in order to provide increased confidence in the formation of a particular lesion profile or pattern (e.g., volume, shape, or zone) by energy delivery. For example, a parallel orientation may form a shallower but longer or wider lesion profile, a perpendicular orientation may form a deeper but narrower lesion profile, and an oblique orientation may form a lesion profile somewhere between the parallel and perpendicular orientations. In some embodiments, a particular orientation may be targeted by a clinical professional and the orientation determination may confirm to the clinical professional that the target orientation has been achieved. In some cases, if the target orientation is not reached, the clinical professional may decide to terminate energy delivery, to adjust parameters of energy delivery based on the determined orientation, or to perform additional treatments at the treatment site near the current treatment site to increase the likelihood of continuous lesion formation without gaps.

Fig. 23C illustrates an embodiment of a process 23000 for determining an orientation of a distal end of a medical instrument (e.g., an ablation catheter) relative to a target tissue (e.g., a blood vessel surface or a cardiac tissue surface) when the medical instrument applies energy (e.g., radio frequency energy) to the target tissue. When executing instructions stored on one or more computer-readable media (e.g., non-transitory, non-volatile memory or storage devices), process 23000 may be performed by one or more processors communicatively coupled with the medical instrument (e.g., via a wire or cable or via wireless communication such as via bluetooth or a wireless network). Process 23000 can advantageously result in an orientation or alignment determination in a very short amount of time after initiation of treatment (e.g., within less than fifteen seconds, within less than ten seconds, within less than eight seconds, within less than five seconds, within less than three seconds, within less than two seconds, in the first 40% of the total treatment duration, in the first 30% of the total treatment duration, in the first 25% of the total treatment duration, in the first 20% of the total treatment duration, in the first 15% of the total treatment duration, in the first 10% of the total treatment duration, in the first 5% of the total treatment duration after initiation of energy delivery). The treatment time (e.g., ablation duration) may be very short (e.g., less than 30 seconds); thus, if the orientation determination is not made quickly, the orientation determination may not be performed until after the treatment is complete or substantially complete, and the orientation determined at that time may not accurately reflect the orientation during a substantial portion of the treatment because the orientation of the ablation catheter or other medical device may change during the treatment (e.g., tissue movement due to contraction and relaxation of muscle tissue, movement of the patient or operator, and/or respiration).

The process 23000 begins when therapy (e.g., ablation energy delivery) is initiated and includes three phases: an initiation phase, a temperature rise phase and a steady state phase. In an initiation phase, the at least one processor obtains temperature measurements from a plurality of temperature measurement devices distributed along a length of an elongate body of the medical instrument for a first period of time (block 23005). Obtaining the temperature measurement may include receiving a signal indicative of the temperature and determining a temperature measurement value based on the received signal (which may be performed, for example, by a temperature processing module executed by the at least one processor, such as described above). The first time period may begin when therapy by the medical device (e.g., energy delivery) is initiated and may last for the first time period (e.g., between 1 and 5 seconds, between 1 and 2 seconds, between 1 and 3 seconds, between 2 and 4 seconds, between 3 and 5 seconds, between 1 second, 1.5 seconds, 2 seconds, 2.5 seconds, 3 seconds, 3.5 seconds, 4 seconds, 4.5 seconds, 5 seconds, overlapping ranges thereof, or any value within the range). In some embodiments, the temperature measurements are obtained at a plurality of time points or measurement points (e.g., at regular intervals within the first duration of the initiation phase, or at a plurality of irregular or non-periodic time points within the first duration of the initiation phase). The first duration may be varied as desired and/or required for optimization. Measurements may be obtained and recorded at any desired frequency (e.g., every 1ms, every 5ms, every 10ms, every 50ms, or every 100 ms). At block 23010, a starting temperature of each temperature measurement device (e.g., thermocouple or thermistor) is determined based on the temperature measurements obtained during the first time period. Each temperature measurement device may be associated with a channel that may be tracked and plotted (and output on a display for viewing). In some embodiments, the starting temperature is determined by averaging temperature measurements obtained during the first time period. Any of the configurations or arrangements of temperature measurement devices described herein may be used. For example, the temperature measurement device may include a plurality of distal temperature measurement devices and a plurality of proximal temperature measurement devices spaced proximal to the plurality of distal temperature measurement devices, as discussed herein.

After determining the starting temperature, process 23000 proceeds to a temperature ramp-up phase. The temperature rise phase corresponds to the following times: during this time interval, the temperature measurement increases due to heating of the tissue caused by the application of energy (e.g., RF energy) to the tissue. During the temperature ramp-up phase, temperature measurements are successively obtained and recorded from each of the temperature measurement devices (block 23015). Obtaining the temperature measurement may include receiving a signal indicative of the temperature and determining a temperature measurement value based on the received signal. Also, the frequency of the temperature measurements may be varied as desired and/or required for optimization. In some embodiments, the temperature measurements are obtained at a plurality of time points or measurement points (e.g., at regular intervals within a period of the temperature ramp-up phase, or at a plurality of irregular or non-periodic time points within the period of the temperature ramp-up phase). For example, temperature measurements may be obtained every 0.1 second, every 0.5 seconds, every second, and so forth. The temperature ramp-up phase may last for a second period of time (e.g., from one second to thirty seconds after initiation of energy delivery, from one second to twenty seconds after initiation of energy delivery, from one second to eighteen seconds after initiation of energy delivery, from five seconds to eighteen seconds after initiation of energy delivery, from three seconds to thirteen seconds after initiation of energy delivery, from five seconds to ten seconds after initiation of energy delivery, overlapping ranges thereof, or any value within the range).

At each measurement time point during the temperature ramp-up phase, a characteristic of the temperature response of each temperature measurement device (or each channel associated with the respective temperature measurement device) is determined (e.g., computed or operated on by at least one processor or computing device) based on the obtained temperature measurements (block 23020). In some embodiments, the characteristic is a rate of change of temperature (e.g., how fast temperature measurements obtained by the temperature measurement device increase over time). As another example, the characteristic may be a temperature rise value calculated for each temperature measurement device (or each channel associated with the respective temperature measurement device) by subtracting a starting temperature value (e.g., Tn-Ts) from a current temperature value. In some embodiments, a moving average is applied over time to remove "noise" or fluctuations in the temperature measurements, and the starting temperature value is subtracted from the moving average to determine a temperature rise value. The moving average window may be nominally 1 second, but may be varied to account for variations in temperature measurement response, such as cardiac and respiratory artifacts (e.g., 0.1 second, 0.5 second, 1 second, 1.5 second, 2 seconds, 2.5 seconds, 3 seconds, 3.5 seconds, 4 seconds, 4.5 seconds, 5 seconds, or any value between 0.1 second and 5 seconds). The rate of change may be determined by dividing the temperature rise value by the duration of time between the current time and the start time. For example, at n seconds, there is a measured temperature value Tn between n-1 seconds and n seconds. The starting temperature value can be subtracted from Tn and then divided by n to obtain the rate of change at n seconds.

At block 23025, the one or more processing devices (e.g., upon execution of the temperature processing module) determine an orientation or alignment of the distal end of the medical instrument based on one or more orientation criteria (e.g., thresholds, tests, or conditions) that depend on the determined characteristics of at least two of the temperature measurement devices. Orientation determination may be performed at each measurement point or point in time at which a measurement is obtained or determined, advantageously indicating whether the orientation has changed during the course of treatment (e.g., as a result of patient or operator movement or other perturbations). The determination of the orientation may include performing different comparisons between characteristics of temperature responses (e.g., temperature rise values or rates of change) between two or more of the temperature measurement devices. For example, a comparison may be performed between the characteristics of the proximal temperature measurement device and the distal temperature measurement device at each point in time or measurement point (such as an average of the temperature rise values or rates of change of the proximal temperature measurement device or an average of the temperature rise values or rates of change of the distal temperature measurement device, or a minimum of the temperature rise values or rates of change of the proximal temperature measurement device or a minimum of the temperature rise values or rates of change of the distal temperature measurement device, or a maximum of the temperature rise values or rates of change of the proximal temperature measurement device or a maximum of the temperature rise values or rates of change of the distal temperature measurement device). As one example, the one or more processing devices may determine that the orientation is tilted if the average proximal temperature rise or rate of change is greater than the average distal temperature rise or rate of change by some factor N, where N may be any real number. According to several embodiments, an accurate determination of orientation may be made more quickly after initiating energy delivery by determining orientation based on a comparison of characteristics of the temperature response (e.g., rate of change or rise value or rise time comparison), rather than based on a comparison of the temperature measurements themselves or spread of temperature measurements once they reach steady state.

The orientation criteria may be determined based on empirical data and may be stored in a look-up table or memory. In some embodiments, the orientation criteria include a time-dependent (time-dependent) threshold in addition to or instead of a static threshold or condition. For example, the maximum proximal temperature rise or rate of change may be subtracted from the minimum distal temperature rise or rate of change, and this value may be compared to a time-dependent threshold as shown below: DRmin-PRmax ═ a (t-B) + C, where DRmin is the minimum temperature rise of the distal temperature measurement device and PRmax is the maximum temperature rise of the proximal temperature measurement device, and A, B and C are constants determined from empirical data and define how the threshold varies over time. The orientation criteria for the respective orientation option may include a plurality of criteria, one, some or all of which must be met for the orientation option to be selected. A number of criteria can be used to take into account (accountfor) the different alignments or orientations caused by anatomical changes during the temperature ramp-up phase. For example, for an oblique orientation, the following is possible: in one case, the distal electrode member (or one or more temperature measurement devices spaced proximally of the distal electrode member) of the electrode is in contact with the tissue while the proximal electrode member (or one or more temperature measurement devices spaced proximally of the distal electrode member) is not in contact with the tissue, and in another case, the distal electrode member (or one or more temperature measurement devices spaced proximally of the distal electrode member) is not in contact with the tissue while the proximal electrode member (or one or more temperature measurement devices spaced proximally of the distal electrode member) is in contact with the tissue. Two of these cases (which may be caused by anatomical changes) may have completely different temperature response characteristics, but both should be determined as tilted orientations according to several embodiments. Furthermore, in a parallel orientation, it is possible that only one proximal temperature measurement device is in contact with the tissue (and thus generates a higher temperature measurement) while two distal temperature measurement devices are in contact with the tissue (and thus generates a higher temperature measurement). An incorrect orientation may be made by the at least one processing device if only the average comparison is made. Thus, different orientation criteria may be required to account for variations in the possible orientations of the individual orientation options (and corresponding variations in temperature response characteristics).

The orientation may be determined from one of two possible orientation options (e.g., parallel or perpendicular), or one of three orientation options (e.g., tilt, parallel, or perpendicular). The definition of tilt, parallel and perpendicular may be adjusted according to the desires and/or requirements of usability and/or performance factors. According to several embodiments involving three orientation options, the parallel orientation may be considered from 0 to 20 degrees (or 160 to 180 degrees), the oblique orientation may be considered from 20 to 80 degrees (or 120 to 160 degrees), and the perpendicular orientation may be considered from 80 to 120 degrees (assuming (between the medical instrument and the tissue) that 0 or 180 degrees of rotation is perfectly parallel, and 90 degrees of rotation is perfectly perpendicular). In embodiments involving three orientation options, the determination of orientation proceeds from first determining whether one or more orientation criteria for the first orientation are met. If one or more orientation criteria for the first orientation are satisfied, the one or more processing devices optionally generate an output indicative of the first orientation at block 23030. If the one or more orientation criteria for the first orientation are not satisfied, the one or more processing devices determine whether the one or more orientation criteria for the second orientation are satisfied. If one or more orientation criteria for the second orientation are satisfied, the one or more processing devices optionally generate an output indicative of the second orientation at block 23030. If the one or more orientation criteria for the second orientation are not satisfied, the one or more processing devices determine by default that the orientation must be the third orientation (because there are only three orientation options), and at block 23030, the one or more processing devices optionally generate an output indicative of the third orientation. If only two orientation options are available, the second orientation is selected by default if the criteria associated with the first orientation are not met. The orientation criteria may vary depending on the order in which the orientation options are tested. If multiple criteria are associated with a particular orientation being tested, the tests may be performed in parallel by separate processors to accelerate the orientation determination process 23000.

As one example, process 23000 may first test the tilt orientation in a temperature ramp-up phase. The tilt orientation criteria may include the following tests: to comparing average temperature rises or rates of temperature change of the distal temperature measurement device and the proximal temperature device (e.g., the proximal average temperature rise or rate of temperature change is greater than the distal average temperature rise or rate of temperature change by a predetermined factor or equal thereto), and/or comparing a minimum temperature rise or rate of temperature change of the distal temperature measurement device to a maximum temperature rise or rate of temperature change of the proximal temperature device (e.g., the difference is less than or equal to a predetermined amount, which may be determined using a time-related equation such as a (t-B) + C, where A, B and C are constants and t is time in seconds). If a tilt orientation criterion (which may be a combination of one or more criteria) is met, a tilt orientation is determined. Otherwise, process 23000 may continue with testing for parallel orientation. The parallel orientation criteria may include the following tests: to comparing average temperature rises or rates of temperature change of a distal temperature measurement device and a proximal temperature measurement device (e.g., the absolute value of the difference between the two average values divided by the proximal average temperature rise or rate of temperature change is less than or equal to a predetermined amount) and/or comparing maximum temperature rises or rates of temperature change of the distal temperature measurement device and the proximal temperature measurement device (e.g., the difference between the maximum values is less than or equal to a predetermined amount, which may be determined using an equation related to time (such as a (t-B) + C, where A, B and C are constants and t is time in seconds). If a parallel orientation criterion (which may be a combination of one or more criteria) is met, then a parallel orientation is determined. Otherwise, process 23000 can determine that the orientation is vertical.

After the second time period has elapsed, process 23000 proceeds to a steady-state phase corresponding to a third time period in which the temperature measurements (or the profile of the channel plotted on the graph) have reached steady state such that the temperature measurements (e.g., peak temperature measurements) do not change or fluctuate a significant amount (e.g., less than 20%, less than 15%, less than 10%, less than 5%, less than 4%, less than 3%, less than 2%) between measurement points or between points in time at which the measurements were obtained. According to several embodiments, because temperature measurements typically do not change significantly during steady-state phases, orientation or alignment determinations need not be made based on time-related conditions or based on characteristics of the temperature response (such as the rate of change of the temperature rise). Thus, in the steady-state phase, a different set of orientation criteria is used to make the orientation determination than was used in the temperature ramp-up phase. Although the temperature measurements do not nominally change significantly, the orientation determination in the steady-state phase may be designed to react to deviations and changes in temperature due to, for example, patient or operator movement or other disturbances. Also, the orientation criteria for the steady state phase are different for each orientation option and may vary depending on the order in which the orientation options are tested.

At block 23035, temperature measurements (e.g., values) are continuously obtained from each of the distributed temperature measurement devices at periodic intervals (e.g., multiple points in time or measurement points) during a third time period. Similar to the temperature ramp-up phase, a moving average may be applied to each of the temperature measurement device channels; however, since the deviation or fluctuation of the temperature measurement values in the steady-state phase is small, the averaging window in the steady-state phase may be different. For example, the averaging window in the steady state phase may be longer than the averaging window in the temperature ramp-up phase. The average window may be nominally 5 seconds, but may vary depending on the type of instrument used and the treatment provided (e.g., any value between 0.5 to 10 seconds, such as 0.5 seconds, 1 second, 1.5 seconds, 2 seconds, 2.5 seconds, 3 seconds, 3.5 seconds, 4 seconds, 4.5 seconds, 5 seconds, 5.5 seconds, 6 seconds, 6.5 seconds, 7 seconds, 7.5 seconds, 8 seconds, 8.5 seconds, 9 seconds, 9.5 seconds, 10 seconds). An orientation of the distal end of the medical instrument (e.g., an electrode tissue orientation) is determined at each measurement point during the third time period continuously based on a steady-state phase orientation criterion that is different from a temperature ramp-up phase orientation criterion (block 23040). By continuously determining the orientation at each time measurement point, a more accurate estimate of the lesion profile formed by the treatment at that particular target site may be obtained, and further treatment may be adjusted accordingly if desired or needed. According to several embodiments, the orientation criterion in the steady-state phase only comprises static thresholds or conditions, and not time-dependent thresholds or conditions. For example, the orientation criteria may be one or more of the following: comparing a maximum of the temperature values of the distal temperature measurement device or channel with a maximum of the temperature values of the proximal temperature measurement device or channel, comparing a minimum of the temperature values of the distal temperature measurement device or channel with a maximum of the temperature values of the proximal temperature measurement device or channel, or comparing a maximum of the temperature values of the distal temperature measurement device or channel with a minimum of the distal temperature values of the proximal temperature measurement device or channel.

The orientation criteria for the steady state phase may be based on empirical data and stored in a look-up table or memory. The orientation criteria for the respective orientation option in the steady-state phase may comprise a plurality of criteria, one, some or all of which must be met for the orientation to be selected. For the temperature ramp-up phase, a number of criteria may be used to account for different alignments or orientations caused by anatomical changes in the steady-state phase. For example, for an oblique orientation, the following is possible: in one case, the distal electrode member (or one or more temperature measurement devices spaced proximally of the distal electrode member) of the electrode is in contact with the tissue while the proximal electrode member (or one or more temperature measurement devices spaced proximally of the distal electrode member) is not in contact with the tissue, and in another case, the distal electrode member (or one or more temperature measurement devices spaced proximally of the distal electrode member) is not in contact with the tissue while the proximal electrode member (or one or more temperature measurement devices spaced proximally of the distal electrode member) is in contact with the tissue. Two of these cases (which may be caused by anatomical changes) may have completely different temperature measurements or temperature response characteristics, but according to several embodiments both should be determined as tilt orientations in the steady state phase. Thus, different orientation criteria may be required to account for variations in the possible orientations of the individual orientation options (and corresponding variations in temperature measurements or temperature response characteristics).

Similar to the temperature ramp-up phase, the determination of the orientation in the steady-state phase may be made by first determining whether the orientation criterion of the first orientation is met. If the criteria for the first orientation are not met, the process proceeds to determine if the criteria for the second orientation are met. If the criteria for the second orientation are not satisfied, the process may determine that the orientation is a third orientation. At block 23045, the one or more processing devices optionally generate an output indicative of the determined orientation. The steady state phase continues until the application of energy is terminated. In other embodiments, temperature measurements obtained during steady state phases may not be obtained at periodic intervals. In some embodiments, process 23000 does not include a steady-state phase, and process 23000 ends before block 23035.

As one example of an orientation determination operation at block 23040, the first orientation to be tested in the steady-state phase is a tilt orientation. The tilt orientation may include one or more of: the method may include comparing average temperature measurements of the distal temperature measurement device and the proximal temperature device (e.g., the difference is less than a predetermined amount), comparing a maximum distal temperature measurement value and a maximum proximal temperature measurement value (e.g., the difference is less than a predetermined amount), comparing a minimum temperature measurement value of the distal temperature measurement device and a maximum temperature measurement value of the proximal temperature device, comparing an intermediate temperature measurement value of the distal temperature measurement device and a maximum temperature measurement value of the proximal temperature device, comparing a minimum temperature measurement value of the proximal temperature measurement device and a maximum temperature measurement value of the distal temperature device, and comparing an intermediate (or median) temperature measurement value of the proximal temperature measurement device and a maximum temperature measurement value of the distal temperature device. One, some, or all of the criteria may need to be met to determine the tilt orientation as the current orientation. If a tilt orientation criterion (which may be a combination of one or more criteria) is met, a tilt orientation is determined. Otherwise, process 23000 may continue with testing for parallel orientation. The parallel orientation criteria may include tests involving: the average temperature measurements of the distal temperature measurement device and the proximal temperature measurement device are compared (e.g., the difference between the two average values is within a predetermined range) and/or the maximum temperature measurements of the distal temperature measurement device and the proximal temperature measurement device are compared (e.g., the difference between the maximum values is within a predetermined range). If a parallel orientation criterion (which may be a combination of one or more criteria) is met, then a parallel orientation is determined. Otherwise, process 23000 can determine that the orientation is vertical.

As another example of the orientation determination operation at block 23040, process 23000 may first test for vertical orientation in a steady state phase. The vertical orientation criteria may include tests involving any one or more of the following: comparing the maximum temperature measurements of the distal temperature measurement device and the proximal temperature measurement device (e.g., the maximum distal temperature measurement is greater than the maximum proximal temperature measurement by a predetermined temperature value), comparing the minimum temperature measurement of the distal temperature measurement device to the maximum temperature measurement of the proximal temperature measurement device (e.g., the difference is greater than the predetermined temperature value), comparing the maximum and median temperature values of the distal temperature measurement device to the maximum and minimum temperature values of the distal temperature measurement device (e.g., determining that the difference between the maximum and median temperature measurements of the distal temperature measurement device is less than the difference between the maximum and minimum temperature values of the distal temperature measurement device by a predetermined amount), or comparing the maximum and minimum temperature measurements of the distal temperature measurement device to the maximum temperature measurements of the distal temperature measurement device and the proximal temperature measurement device (e.g., the difference between the maximum and minimum temperature measurements of the distal temperature measurement device is less than the difference between the maximum temperature measurements of the distal temperature measurement device and the proximal temperature measurement device). If a vertical orientation criterion (which may be a combination of one or more criteria) is met, then vertical orientation is determined. Otherwise, process 23000 may continue with testing for parallel orientation. The parallel orientation criteria may include tests involving: it is determined whether a difference between maximum temperature measurements of the distal temperature measurement device and the proximal temperature measurement device is within a predetermined range and/or whether a difference between average measurements of the distal temperature measurement device and the proximal temperature measurement device is within a predetermined range. If a parallel orientation criterion (which may be a combination of one or more criteria) is met, then a parallel orientation is determined. Otherwise, process 23000 can determine that the orientation is a tilt.

Fig. 23D and 23E illustrate two example embodiments of processes 23050, 23075 for determining the orientation of the distal end of a medical device relative to a target region (e.g., cardiac tissue or a vessel wall). Each of the processes 23050, 23075 begins by determining or specifying orientation criteria (e.g., thresholds or conditions for at least two of the orientation options) (blocks 23055, 23080). As previously discussed, the orientation criteria may include static and/or time-dependent thresholds or conditions. The orientation criteria may have been stored in memory or a look-up table and simply accessed prior to initiating the process, or may be determined in real time. The processes 23050, 23075 can be performed in a temperature ramp phase or a steady state phase.

Process 23050 begins by determining whether one or more orientation criteria for a tilt orientation are satisfied. The criteria may include one criterion or a plurality of criteria. If there are multiple criteria, one or all of the criteria may need to be met. If the criteria for tilt orientation are satisfied, an output indicative of tilt orientation is generated at block 23060. If the criteria for tilt orientation are not satisfied, process 23050 continues to determine if one or more orientation criteria for parallel orientation are satisfied. If the criteria for parallel orientation are met, an output indicating parallel orientation is generated at block 23065. If the criteria for parallel orientation are not satisfied, an output indicating vertical orientation is generated by default at block 23070. Process 23075 is similar to process 23050 except that the order of orientation is changed such that testing is performed first for a vertical orientation (where an output indicative of a vertical orientation is generated at block 23085 if the corresponding orientation criteria are met) instead of a tilted orientation, and the default orientation is a tilted orientation instead of a vertical orientation (where an output indicative of a tilted orientation is generated at block 23095 if the orientation criteria for a vertical orientation and a parallel orientation are not met). As with process 23050, if the orientation criteria for parallel orientation are met, an output indicating parallel orientation is generated at block 23090. The orientation may be tested in any order. For example, a parallel orientation may be tested first, rather than a tilted orientation or a perpendicular orientation as shown in fig. 23D and 23E, respectively. According to several embodiments, the tilt orientation is tested first, since it is the most likely orientation, and thus testing first for tilt orientation may reduce determination time.

In some embodiments, the processor is configured to cause the output generated by processes 23050 and 23075 to reach the display indicating the particular orientation. The output may include textual information (such as words, phrases, letters, or numbers). In some embodiments, the display comprises a graphical user interface and the output comprises one or more graphical images indicative of the determined orientation. The orientation determination process is performed at each time point or measurement point and the output is continuously updated based on the current orientation determination, advantageously indicating whether the orientation has changed during the course of the treatment, which may indicate a possible deviation from the expected lesion profile.

23F-1, 23F-2, and 23F-3 illustrate various embodiments of output on a graphical user interface (e.g., a graphical user interface communicatively coupled to a display screen on a radio frequency generator or a computing device of one or more processors of an energy delivery system). As shown, the output may include three radio buttons (radio buttons) 23105, each having a label 23110 identifying one of the orientation options (e.g., vertical, oblique, and parallel). In some embodiments, the radio buttons corresponding to the determined orientation may be marked or distinguished from other radio buttons (e.g., having an illuminated appearance, as shown by the light emitted by one of the radio buttons in fig. 23F). The indicia may include a fill of the corresponding radio button, a highlight of the corresponding radio button, or a change in color of the corresponding radio button. In one embodiment, the radio button may appear as an LED, and the LED corresponding to the determined orientation may be changed to green or otherwise "illuminated" to signal (signal) the determined orientation. The output may also include a graphical image 23115 of the electrode icon or the distal end of the medical instrument in the determined orientation. As shown, the output may also include a graphical image of the arrow oriented according to the determined orientation. FIG. 23F-1 shows an example output when the parallel orientation is determined, FIG. 23F-2 shows an example output when the tilt orientation is determined, and FIG. 23F-3 shows an example output when the vertical orientation is determined. The radio buttons may be replaced with check boxes (checkboxes) or other visual indicators.

Contact sensing

According to some embodiments, disclosed herein are various implementations of electrodes (e.g., radio frequency or RF electrodes) that may be used for high-resolution mapping and radio frequency ablation. For example, as discussed in more detail herein, an ablation or other energy delivery system may include a high resolution or combined electrode design in which the energy delivery member (e.g., radio frequency electrode, laser electrode, microwave emitting electrode) includes two or more separate electrodes or electrode members or portions. As also discussed herein, in some embodiments, such separate electrodes or electrode portions may advantageously be electrically coupled to one another (e.g., to collectively create a desired heating or ablation of the target tissue). In various embodiments, a combination electrode or composite (e.g., split tip) design may be utilized to determine whether one or more portions of an electrode or other energy delivery member are in contact with tissue (e.g., endocardial tissue) and/or whether the contacted tissue has been ablated (e.g., to determine whether the tissue is viable).

Several embodiments of the invention are particularly advantageous as they include one, several or all of the following advantages: (i) confirmation of actual tissue contact is easily explorable; (ii) confirmation of contact with ablated and non-ablated (living) tissue is easily explorable; (iii) low cost because the present invention does not require any special sensors; (iv) the use of a radiometer is not required; (v) providing various forms of output or feedback to a user; (vi) providing output to a user without requiring the user to be looking at the display; and/or (vii) provide a safer and more reliable ablation procedure.

Referring to fig. 1, according to some embodiments, delivery module 40 includes a processor 46 (e.g., a processing or control device), the processor 46 configured to adjust one or more aspects of treatment system 10. Delivery module 40 may also include a memory unit or other storage device 48 (e.g., a non-transitory computer-readable medium), which memory unit or other storage device 48 may be used to store operating parameters and/or other data related to the operation of system 10. In some embodiments, processor 46 includes or is in communication with a contact sensing and/or tissue type detection module or subsystem. The contact sensing subsystem or module may be configured to determine whether the energy delivery member(s) 30 of the medical instrument 20 are in contact with tissue (e.g., contact sufficient to provide effective energy delivery). The tissue type detection module or subsystem may be configured to determine whether tissue in contact with the one or more energy delivery member(s) 30 has been ablated or otherwise treated. In some embodiments, the system 10 includes a contact sensing subsystem 50. The contact sensing subsystem 50 may be communicatively coupled to the processor 46 and/or include a separate controller or processor and memory or other storage medium. The contact sensing subsystem 50 may perform both contact sensing and tissue type determination functions. The contact sensing subsystem 50 may be a discrete, stand-alone subassembly of the system (as schematically shown in fig. 1), or may be integrated into the energy delivery module 40 or the medical device 20. Additional details regarding the touch sensitive subsystem are provided below.

In some embodiments, the processor 46 is configured to automatically adjust the delivery of energy from the energy generating device 42 to the energy delivery member 30 of the medical instrument 20 based on one or more operating schemes. For example, the energy provided to energy delivery member 30 (and thus the amount of heat transferred to or from the target tissue) may be adjusted based on, among other things, the detected temperature of the tissue being treated, whether it is determined that the tissue has been ablated, or whether energy delivery member 30 is determined to be in contact with the tissue to be treated (e.g., "sufficient" contact or contact at a level above a threshold).

Referring to fig. 24, the distal electrode 30A may be energized using one or more conductors (e.g., wires, cables, etc.). For example, in some arrangements, the exterior of the irrigation tube includes and/or is otherwise coated with one or more electrically conductive materials (e.g., copper, other metals, etc.). Accordingly, one or more conductors may be placed in contact with such conductive surfaces or portions of the irrigation tube to electrically couple the electrode or electrode portion 30A to an energy delivery module (e.g., energy delivery module 40 of fig. 1). However, one or more other devices and/or methods of placing the electrode or electrode portion 30A in electrical communication with the energy delivery module may be used. For example, one or more wires, cables, and/or other conductors may be coupled directly or indirectly to the electrodes without the use of irrigation tubing. The energy delivery module may be configured to deliver electromagnetic energy at a frequency useful for determining contact (e.g., between 5kHz and 1000 kHz).

Fig. 24 schematically illustrates one embodiment of a combination or composite (e.g., split tip) electrode assembly that may be used to perform contact sensing or determination by measuring bipolar impedance at different frequencies between separate electrodes or electrode portions 30A, 30B. The resistance value may be determined from the voltage and current based on ohm's law: voltage-current-resistance, or V-IR. Thus, the resistance is equal to the voltage divided by the current. Similarly, if the impedance between the electrodes is complex (complex), complex voltages and currents may be measured and the impedance (Z) determined by V _ complex I _ complex Z _ complex. In this case, both the amplitude and phase information of the impedance can be determined from the frequency. The different frequencies may be applied to the compound (e.g., split-tip) electrode assembly by an energy delivery module (e.g., by energy generation device 42 of energy delivery module 40 of fig. 1) or a contact sensing subsystem (such as contact sensing subsystem 50 of system 10 of fig. 1). Since the voltage and current values can be known or measured, the resistance and/or complex impedance values can be determined from the voltage and current values using ohm's law. Thus, according to several embodiments, impedance values may be calculated based on measured voltage and/or current values, rather than obtaining impedance measurements directly.

Fig. 25A is a graph showing resistance or amplitude impedance values of blood (or blood/saline combination) and cardiac tissue over a range of frequencies (5kHz to 1000 kHz). The impedance values are normalized by dividing the measured impedance magnitude by the maximum impedance magnitude value. It can be seen that the normalized impedance of the blood (or blood/saline combination) does not vary significantly over the entire frequency range. However, the normalized impedance of cardiac tissue does vary significantly over this frequency range, forming a roughly "sigmoid" curve.

In one embodiment, resistance or impedance measurements may be obtained at two, three, four, five, six, or more than six different discrete frequencies within a certain frequency range. In several embodiments, the frequency range may span a frequency range for ablating or otherwise heating the target tissue. For example, two different frequencies f may be within the frequency range₁And f₂Obtaining a resistance or impedance measurement, wherein f₂Greater than f₁. Frequency f₁Or below the ablation frequency range, and frequency f₂May be higher than the ablation frequency range. In other embodiments, f₁And/or f₂May be in the ablation frequency range. In one embodiment, f₁Is 20kHz, and f₂Is 800 kHz. In various embodiments, f₁Between 10kHz and 100kHz, and f₂Between 400kHz and 1000 kHz. When executing certain program (machine-readable) instructions stored on a non-transitory computer-readable storage medium, a processing device (e.g., a contact sensing subsystem or module coupled to processor 46 of fig. 1 or executable by processor 46 of fig. 1) may determine whether electrode portion 30A is in contact with tissue (e.g., cardiac tissue) by comparing impedance magnitude values obtained at different frequencies. The processing device is adapted to communicate with and execute a module for processing data (e.g., a contact sensing module), wherein the module is stored in a memoryIn the device. The module may include software in the form of algorithms or machine-readable instructions.

For example if at a higher frequency f₂The impedance amplitude value obtained at the lower frequency f₁The ratio r of the impedance magnitude values obtained below is less than a predetermined threshold, the processing device may determine that the electrode portion 30A is in contact with cardiac tissue or other target area (e.g., upon execution of certain program instructions stored on a non-transitory computer-readable storage medium). However, if at a higher frequency f₂The impedance amplitude value obtained at the lower frequency f₁The ratio r of the impedance magnitude values obtained below is greater than the predetermined threshold, the processing device may determine that the electrode portion 30A is not in contact with the cardiac tissue, but instead is in contact with blood or a blood/saline combination. The contact determination can be expressed as follows:

in various embodiments, the predetermined threshold has a value between 0.2 and less than 1 (e.g., between 0.2 and 0.99, between 0.3 and 0.95, between 0.4 and 0.9, between 0.5 and 0.9, or overlapping ranges thereof).

In various embodiments, resistance or impedance measurements are obtained periodically or continuously at different frequencies (e.g., two, three, four, or more different frequencies) by utilizing a source voltage or current waveform (as shown in fig. 25B) that is a multi-tone (multi-tone) signal that includes the frequency of interest. As shown in fig. 25C, the polyphonic signals or waveforms may be sampled in the time domain and then transformed to the frequency domain to extract the resistance or impedance at the frequency of interest. In some embodiments, the measurements or determinations indicative of contact may be obtained in the time domain rather than the frequency domain. Signals or waveforms having different frequencies may be used. According to several embodiments, performing a touch sensing operation is designed to have little impact on the Electrogram (EGM) function of a combined or compound (e.g., split tip) electrode assembly. For example, as shown in fig. 25D, a common mode choke and a DC blocking circuit may be utilized in the path of the impedance measurement circuitry. The circuitry may also include a reference resistor R for limiting the maximum current flowing to the patient, and dual voltage sampling points V1 and V2 for enhancing the accuracy of the impedance measurement. Additionally, as shown in fig. 4D, a low pass filter circuit (e.g., with a cutoff frequency of 7 kHz) may be utilized in the path of the EGM recording system. In several embodiments, all or part of the circuitry shown in fig. 25D is used in a contact sensing subsystem, such as contact sensing subsystem 50 of fig. 1 or contact sensing subsystem 4650 of fig. 27. The frequency for contact sensing may be at least greater than five times the EGM recording or mapping frequency, at least greater than six times the EGM recording or mapping frequency, at least greater than seven times the EGM recording or mapping frequency, at least greater than eight times the EGM recording or mapping frequency, at least greater than nine times the EGM recording or mapping frequency, at least greater than ten times the EGM recording or mapping frequency. The contact sensing subsystem may be controlled by a processing device including, for example, an analog-to-digital converter (ADC) and a Microcontroller (MCU). The processing device may be integrated with the processing device 46 of fig. 1 or may be a separate, stand-alone processing device. If a separate processing device is used, the separate processing device may be communicatively coupled to the processing device 46 of FIG. 1.

In various embodiments, resistance or impedance measurements (e.g., components of total or complex impedance) are obtained periodically or continuously at different frequencies (e.g., two or three different frequencies) by switching between different frequencies. According to several embodiments, performing a touch sensing operation is designed to have little impact on the Electrogram (EGM) function of a combined electrode or composite (e.g., split tip) component. Therefore, as shown in fig. 26A, switching between different frequencies can be advantageously synchronized to the zero-crossing point of the AC signal waveform. In some embodiments, if frequency switching does not occur at the zero crossing, artifacts may be caused in the electrogram, thereby reducing the quality of the electrogram. In some embodiments, impedance measurements are obtained at multiple frequencies simultaneously (e.g., bipolar impedance measurements). In other embodiments, impedance measurements are obtained sequentially at multiple frequencies.

In another embodiment, by spanning from f_{Minimum size}To f_{Maximum of}(e.g., 5kHz to 1MHz, 10kHz to 100kHz, 10kHz to 1MHz) obtain resistance or impedance measurements throughout a frequency range to perform touch sensing or determination. In such embodiments, a change in frequency response or impedance measurement over a range of frequencies indicates whether the electrode portion 30A is in contact with tissue (e.g., cardiac tissue).

Impedance measurements may be applied to the model. For example, a frequency response function r (f) may be created and fitted to a polynomial or other fitting function. This function may take the form of, for example:

r(f)＝a·f³+b·f²+c·f+d

where a, b, c, and d are terms of a polynomial function that matches r (f) response to measured data. A threshold may then be set on the polynomial term to determine whether the electrode is in contact with tissue. For example, a large d term may indicate a large impedance indicating tissue contact. Similarly, a large c term may indicate a large slope of impedance, which also indicates tissue contact. Higher order terms may be utilized to reveal other subtle differences in impedance response indicative of tissue contact.

In some embodiments, a circuit model such as that shown in fig. 26B is used to determine the frequency response function r (f). The model may include resistors and capacitors that predict tissue and tissue-to-electrode interface responses. In such a method, R and C values that best fit the measured data may be determined, and a threshold may be utilized based on the R and C values to determine whether the electrode is in contact with tissue. For example, a small capacitance value (C2) may indicate a condition of tissue contact, while a large capacitance value may indicate no contact. Other circuit configurations are possible to model the behavior of the electrode impedance as desired and/or needed.

In some embodiments, contact sensing or contact determination assessment is performed prior to initiating ablation energy delivery, rather than during an energy delivery periodThe process is performed. In this case, as shown in fig. 26C, the contact impedance measurement circuitry can be separated from the ablation energy using a switch. In this implementation, switch SW1 is opened to disconnect the composite (e.g., split tip) capacitor (C)_ST) And allowed to stand at C_STThe measurement of impedance in the higher frequency range of a short circuit (or low impedance in parallel with the measurement) may occur. Also, switches SW2 and SW3 are provided to connect to impedance measurement circuitry or to the touch sensing subsystem. As shown in fig. 26C, the impedance measurement circuit or contact sensing subsystem is the same as that shown in fig. 25D. When ablation is to be performed, SW2 and SW3 connect the tip electrode to a source of ablation energy (e.g., an RF generator labeled RF in fig. 26C) and disconnect the impedance measurement circuit. To connect a composite (e.g. split tip) capacitor C_STSW1 is also switched, allowing the pair of electrodes to be electrically connected via a low impedance path. In one embodiment, a split tip capacitor C_STIncluding a 100nF capacitor that introduces a series impedance below about 4 Ω at 460kHz, which is the target frequency for radio frequency ablation, according to some arrangements. As also shown in fig. 26C, the ablation current path is from both electrodes to a common ground pad. The impedance measurement path is between the two electrodes, but other current paths for impedance measurement are possible. In one embodiment, the switch is a relay, such as an electromechanical relay. In other embodiments, other types of switches (e.g., solid state, MEMS, etc.) are used.

In some embodiments, the above-described contact sensing or contact determination assessment may be performed while delivering ablation energy or power (e.g., ablation radiofrequency energy or power), as the frequency used for contact sensing is outside the range of (greater than or less than) the ablation frequency(s), or both greater than and less than the ablation frequency (s)).

Fig. 27 schematically illustrates a system 4600, the system 4600 including a high resolution combined electrode or a compound (e.g., split tip) electrode catheter, the system being configured to simultaneously perform an ablation procedure and a contact sensing or determination procedure. The high resolution (e.g., compound or split tip) electrode assembly 4615 may include two electrodes or two electrode members or portions 4630A, 4630B separated by a gap. The separator is located within the gap G between the electrodes or electrode portions 4630A, 4630B. The composite electrode assembly 4615 may include any of the features of the high resolution (e.g., composite or split tip) electrode assemblies described above in connection with fig. 2 and/or as otherwise disclosed herein. An energy delivery module (not shown), such as energy delivery module 40 of fig. 1, or other signal source 4605 may be configured to generate, deliver, and/or apply signals in the ablation range (e.g., radio frequency energy 200 kHz-800 kHz, and nominally 560kHz) while a contact sensing subsystem 4560, such as the contact sensing subsystem shown in fig. 25D, delivers low power signal(s) 4607 (such as excitation signals) in a different frequency range (e.g., between 5kHz and 1000kHz) that are used to perform contact sensing or determine an assessment of the composite electrode assembly 4615. The low power signal(s) 4607 may include a multi-tone signal or waveform or separate signals having different frequencies. Contact sensing subsystem 4650 may include the elements shown in fig. 25D, as well as a notch filter circuit for blocking the ablation frequency (e.g., a 460kHz notch filter if a 460kHz ablation frequency is used). In this configuration, the contact sensing frequency and the ablation frequency(s) are separated by a filter 4684.

The filter 4684 may include, for example, LC circuit elements, or one or more capacitors without inductors. The elements and values of the components of the filter 4684 may be selected such that the minimum impedance is centered at the center frequency of the ablation frequency delivered by the energy delivery module to achieve ablation of the target tissue. In some embodiments, the filtering element 4684 comprises a single capacitor that electrically couples the two electrodes or electrode portions 4630A, 4630B when a radio frequency current is applied to the system. In one embodiment, the capacitor comprises a 100nF capacitor that introduces a series impedance below about 4 Ω at 460kHz, which is the target frequency for ablation (e.g., RF ablation), according to some arrangements. However, in other embodiments, the capacitance of the capacitor(s) or other band pass filtering elements incorporated into the system may be greater than or less than 100nF (e.g., 5nF to 300nF), as desired or required, depending on the operating ablation frequency. In this case, the contact sensing impedance frequencies are all below the ablation frequency range; however, in other implementations, at least some of the contact sensing impedance frequency is within or above the ablation frequency range.

Fig. 28 shows a graph of the impedance of an LC circuit element, for example, including a filter 4684. As shown, the minimum impedance is centered at the center frequency of the ablation RF frequency (460 kHz as one example), and the impedance is high at frequencies in the EGM spectrum so as not to affect the EGM signal or contact sensing measurements. Additionally, contact impedance measurements are performed at frequencies that exist above and/or below the RF frequency (and above the EGM spectrum). For example, two frequencies f may be used₁And f₂Wherein f is₁20kHz and f ₂800 kHz. At these frequencies, the LC circuit will have a large impedance in parallel with the electrodes, allowing the impedance to be measured. In one embodiment, inductor L has an inductance value of 240 μ H and capacitor C has a capacitance value of 5 nF. However, in other embodiments, the inductor L may range from 30 μ H to 1000 μ H (e.g., 30 to 200 μ H, 200 to 300 μ H, 250 to 500 μ H, 300 to 600 μ H, 400 to 800 μ H, 500 to 1000 μ H, or overlapping ranges thereof) and the capacitor C may range from 0.12nF to 3.3 μ F (e.g., 0.12 to 0.90nF, 0.50 to 1.50nF, 1nF to 3nF, 3nF to 10nF, 5nF to 100nF, 100nF to 1 μ F, 500nF to 2 μ F, 1 μ F to 3.3 μ F, or overlapping ranges thereof). In various embodiments, f₁Between 10kHz and 100kHz, and f₂Between 400kHz and 1000 kHz.

According to several embodiments, the same hardware and implementations as used for contact sensing may be used to determine the tissue type (e.g., living tissue versus ablated tissue) in order to confirm whether ablation was successful. FIG. 29 is a graph showing the resistance or impedance magnitude, value of ablated tissue, living tissue, and blood over a range of frequencies. It can be seen that the resistance of the ablated tissue starts at a high resistance value (200 Ω) and remains substantially flat or stable, decreasing slightly in this frequency range. The resistance of the blood starts at a lower resistance (125 Ω) and also remains substantially flat or stable, decreasing slightly in this frequency range. However, the resistance of living tissue starts at a high resistance value (250 Ω) and decreases significantly in this frequency range, roughly forming an "s-shaped" curve. The reason for the difference in resistive response between ablated tissue and living tissue is due, at least in part, to the fact that: living cells (e.g., heart cells) are surrounded by a membrane that acts as a high-pass capacitor, blocking low-frequency, low-frequency signals and allowing higher-frequency signals to pass, while cells that ablate tissue no longer have such a membrane because they are ablated. The reason why the response to the blood resistance is substantially flat is that most blood consists of plasma, which is more or less simply an electrolyte with a low resistance. Red blood cells do provide some differences because they have membranes similar to living heart cells as capacitors. However, since the proportion of red blood cells to blood components is small, the effect of red blood cells is not significant.

Similar to the contact sensing evaluation described above, resistance or impedance amplitude values may be obtained at two or more frequencies (e.g., 20kHz and 800kHz), and these values may be compared to one another to determine a ratio. In some embodiments, if the higher frequency f₂Lower impedance amplitude value and lower frequency f₁If the ratio of impedance magnitude values below is less than the threshold value, then a processing device (e.g., processing device 4624, which may execute a tissue type determination module for processing data, wherein the module is stored in memory and comprises an algorithm or machine-readable instructions) determines that the contacted tissue is living tissue, and if the higher frequency f is less than the threshold value, then the processing device determines that the contacted tissue is living tissue₂Lower impedance amplitude value and lower frequency f₁The ratio of the lower impedance magnitude values is greater than the threshold value, then the processing device 4624 determines that the contacted tissue is ablated tissue. In various embodiments, the predetermined threshold has a value between 0.5 and 0.8 (e.g., 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80).

In some embodiments, at frequency f₂And f₁The combination of the difference in impedance magnitude and the difference in the ratio of impedance magnitudes below is used to determine the contact status (e.g., contact versus in blood) and the tissue type (e.g., living tissue versus ablated tissue). In some embodimentsContact status and tissue type determination is not performed during energy delivery or other treatment procedures. In other embodiments, contact status and/or tissue type determination is performed during an energy delivery or other treatment session using filters and/or other signal processing techniques and mechanisms for separating out different frequency signals.

In addition to impedance magnitude, the same hardware and implementation used for contact sensing (e.g., contact sensing subsystem 50, 4650) may be used to calculate the phase of the impedance (e.g., complex impedance) across the electrode portion. In one embodiment, the phase of the impedance may be added to an algorithm for determining different contact states (e.g., contact versus in blood) and different tissue states (e.g., living tissue versus ablated tissue). Fig. 30 shows an example of the phase of the impedance across the electrode portion with respect to frequency for living tissue, ablated tissue and blood. For blood, the phase tends to be larger (near 0 degrees) and for living (non-ablated) tissue, the phase tends to be smaller. For ablating tissue, the phase may be between blood and living tissue. In one embodiment, a negative phase shift at a single frequency indicates contact with tissue (living or ablated). A larger negative phase shift may indicate contact with living tissue. In one embodiment, a phase of less than-10 degrees at 800kHz indicates contact with tissue (live or ablated). In one embodiment, a phase less than-20.5 degrees at 800kHz indicates contact with living tissue. In other embodiments, the phase at other frequencies or combinations of frequencies is used to determine the contact status and tissue type. In some embodiments, the impedance magnitude and phase are used together as a vector, and the difference of the vector for different frequencies is used to determine the contact state and tissue type.

In some embodiments, the impedance magnitude difference is at frequency f₂And f₁The combination of the difference in the ratio of the impedance amplitude values at (a) and the difference in the phase of the impedance are used together to determine both the contact state (e.g., contact versus in blood) and the tissue type (e.g., living tissue versus ablated tissue). In one embodiment, the determination process 5000 shown in FIG. 31 is utilized to determine both the contact status as well as the tissue type. In the implementation ofIn an example, at block 5005, an impedance magnitude threshold of 150 Ω at 20kHz is used to delineate between no contact and tissue contact (with a larger value indicating contact). Once contact is determined at block 5005, the calculation at f is calculated at block 5010₂800kHz and f₁A ratio of impedance amplitudes at 20kHz, where a value less than 0.6 indicates contact with non-ablated tissue or living tissue. If the aforementioned ratio is greater than 0.6, then the impedance phase at 800kHz is utilized at block 5015, and a (absolute) value of greater than 20.5 degrees indicates contact with the ablated tissue. An (absolute) value of less than 20.5 degrees indicates contact with non-ablated tissue or living tissue.

In some embodiments, the contact sensing subsystem 50 or the system 10 (e.g., the processing device thereof) analyzes the time domain response to the waveform depicted in fig. 25B or to an equivalent waveform. According to several embodiments, contact sensing or tissue type determination is based on processing a response to a signal applied to a pair of electrodes or electrode portions (e.g., electrode pairs 4630A, 4630B), the signal including multiple frequencies or several frequencies applied in sequence. In some embodiments, the processing device 4624 may process the response in the time domain or the frequency domain. For example, considering that blood is mostly resistive with little capacitive characteristics, it is expected that time domain features, such as rise or fall times, lag or advance times, or delays between the applied signal 4402 (e.g., I in fig. 25D) and the processed response 4404 (e.g., V2 in fig. 25D), will exhibit low values. Conversely, if the electrode pair 4630A, 4630B of fig. 27 is in contact with tissue, it is expected that temporal features such as rise or fall times, lag or advance times, or delays between the applied signal 4402 (e.g., I in fig. 25D) and the processed response 4404 (e.g., V2 in fig. 25D) will exhibit higher values, given that the tissue exhibits increased capacitive characteristics. Algorithms that process parameters such as, but not limited to, rise or fall times, lag or advance times, or delays between the applied signal 4402 and the processed response 4404, may indicate or declare contact with the tissue when the parameter exceeds a threshold, or conversely, indicate or declare no contact with the tissue when the parameter has a value below a threshold. For example, assuming that signal 4402 is represented by a sinusoidal current at a frequency of 800kHz, the algorithm may declare contact with tissue if response 4404 lags by more than 0.035 μ s. Conversely, if the response 4404 lag is less than 0.035 μ s, the algorithm can declare no tissue contact. Similarly, if the frequency of signal 4402 is 400kHz, the algorithm may decide to:

-no tissue contact when the lag time is less than 0.07 μ s;

-contact with ablated tissue when the lag time is between 0.07 μ s and 0.13 μ s;

-contact with living tissue or non-ablated tissue when the lag time is greater than 0.13 μ s.

The decision threshold or criterion depends on the waveform of signal 4402. Thresholds or decision criteria for other types of waveforms may also be derived or determined.

In some embodiments, multiple inputs may be combined by a contact sensing or contact indication module or subsystem executable by a processor (e.g., the processor of the contact sensing subsystem 50, 4650) to create a contact function that may be used to provide the following indications: contact versus non-contact, an indication of the amount of contact (e.g., a qualitative or quantitative indication of the level of contact, the state of contact, or the contact force), and/or an indication of the type of tissue (e.g., ablated versus living (non-ablated) tissue). For example, a combination of: (i) at a first frequency f₁Amplitude of impedance of (ii) at two frequencies f₂And f₁(ii) a ratio of impedance amplitudes (defined as slope) or an increment (delta) or change of impedance amplitudes at two frequencies, and/or (iii) a second frequency f₂The phases of the complex impedances below are used together to create a contact function indicative of the contact state (e.g., tissue contact versus in blood). Alternatively, instead of a slope, the derivative of the impedance with respect to frequency may be used. According to several embodiments, the impedance measurement or value comprises a bipolar impedance measurement between a pair of electrode members.

In one embodiment, for at f₁The lower impedance magnitude defines a minimum threshold | Z_minAnd for at f₁Lower impedance magnitude defines the maximum threshold | Z_max. Can sense the contactThe measured impedance magnitude of the subsystem 50, 650 at f1 is normalized such that if the measured result is equal to | Z_minOr lower, the impedance magnitude is 0, and if the measured result is equal to | Z_maxOr higher, the impedance magnitude is 1. In Z-_minAnd | Z |)_maxThe result between can be linearly mapped to a value between 0 and 1. Similarly, one can look for slope (f)₂And f₁The ratio of the impedance magnitudes therebetween) defines a minimum threshold S_minAnd a maximum threshold S_max. Similar minimum and maximum thresholds may be defined if the derivative of impedance with respect to frequency is used. The slope measured by the contact sensing subsystem 50 may be normalized such that if the measured result is equal to or greater than S_minThe slope is 0 and if the measured result is equal to or less than S_maxThe slope is 1. S_minAnd S_maxThe result between can be linearly mapped to a value between 0 and 1. May also be directed to₂The phase of the complex impedance at (A) defines a minimum threshold value (P)_minAnd a maximum threshold value P_max. Can be at f₂The phase measured by the contact sensing subsystem 50 is normalized such that if the measured result is equal to or greater than P_minThe phase is 0 and if the measured result is equal to or less than P_maxThe phase is 1.

According to several embodiments, the resulting three normalization terms of amplitude, slope and phase are combined with a weighting factor for each. The sum of the weighting factors may be equal to 1, such that the resulting addition of the three terms is a touch indicator from zero to a scale (scale) of 1. The weighted Contact Function (CF) can thus be described by the following equation:

wherein | Z |_f1Is at a first frequency f₁The lower measured impedance magnitude, as described above, is clamped at a minimum value | Z_minAnd maximum value | Z $_maxTo (c) to (d); s is a second frequency f₂Amplitude of impedance at₁Ratio of impedance magnitudes of, e.g., aboveSaid, is clamped at a minimum value S_minAnd maximum value S_maxIn the meantime. And P is_f2Is at a frequency f₂The phase of the lower impedance, as described above, is clamped at a minimum value P_minAnd maximum value P_maxIn the meantime. Weighting factors WF1, WF2, and WF3 may be applied to the amplitude, slope, and phase measurements, respectively. As previously mentioned, the weighting factors WF1+ WF2+ WF3 may sum to 1, so that the output of the contact function always provides a value in the range from 0 to 1. Alternatively, values greater than 1 may be allowed to facilitate generating alerts to the user regarding situations where more tissue-electrode contact may become unsafe for the patient. Such alarms may aid in preventing the application of unsafe levels of contact force. For example, a CF value in the range of 1 to 1.25 may be labeled as a "contact alert," and may cause the contact sensing subsystem to generate an alert for display to a user or other output to a user. The alert may be visual, tactile, and/or audible. The weighting factors may vary based on catheter design, connection cables, physical parameters of the patient, and the like. The weighting factors may be stored in memory and may be adjusted or modified (e.g., offset) depending on various parameters. In some embodiments, the weighting factors may be adjusted based on initial impedance measurements and/or patient parameter measurements.

The contact function described above may be optimized (e.g., enhanced or improved) to provide a reliable indicator of the amount of contact with tissue (e.g., cardiac tissue, such as atrial tissue or ventricular tissue). By defining a minimum threshold Z that does not correspond to a minimum tissue contact_min、S_minAnd P_minAnd a threshold value Z corresponding to maximum tissue contact_max、S_maxAnd P_maxTo achieve optimization. The weighting term may also be optimized (e.g., enhanced or improved) for enhanced responsiveness to contact. In some embodiments, a window averaging or other smoothing technique may be applied to the contact function to reduce measurement noise.

As an example, at frequency f₁46kHz and f₂800kHz, value Z_min115 ohm, Z _max175 ohm, S_min＝0.9，S_max＝0.8，P_minAt-5.1 degree, P_maxWF 1-0.75, WF 2-0.15, and WF 3-0.1 are the most desirable (e.g., optimal) for representing the amount of tissue contact (e.g., cardiac tissue for the atria or ventricles). In other embodiments, Z_minMay be in the range from 90 ohms to 140 ohms (e.g., 90 ohms to 100 ohms, 95 ohms to 115 ohms, 100 ohms to 120 ohms, 110 ohms to 130 ohms, 115 ohms to 130 ohms, 130 ohms to 140 ohms, overlapping ranges thereof, or any value between 90 ohms and 140 ohms), Z_maxMay be in a range from 150 ohms up to 320 ohms (e.g., 150 ohms to 180 ohms, 160 ohms to 195 ohms, 180 ohms to 240 ohms, 200 ohms to 250 ohms, 225 to 260 ohms, 240 to 300 ohms, 250 to 280 ohms, 270 to 320 ohms, overlapping ranges thereof, or any value between 150 ohms to 320 ohms), S_minMay be in the range of from 0.95 to 0.80 (e.g., 0.95 to 0.90, 0.90 to 0.85, 0.85 to 0.80, overlapping ranges thereof, or any value between 0.95 to 0.80), S_maxMay be in the range of from 0.85 to 0.45 (e.g., 0.85 to 0.75, 0.80 to 0.70, 0.75 to 0.65, 0.70 to 0.60, 0.65 to 0.55, 0.60 to 0.50, 0.55 to 0.45, overlapping ranges thereof, or any value between 0.85 to 0.45), P_minCan be in the range of from 0 to-10 degrees (e.g., 0, -1, -2, -3, -4, -5, -6, -7, -8, -9, -10 or any combination such as the ranges between 0 to-5, -2 to-6, -4 to-8, -5 to-10), and P_maxCan range from-5 to-25 degrees (e.g., -5 to-10, -7.5 to-15, -10 to-20, -15 to-25, overlapping ranges thereof, or any value between-5 to-25 degrees). The weighting factors WF1, WF2 and WF3 may cover a range of 0 to 1. In some embodiments, values above or below the provided ranges may be used as desired and/or required. The appropriate values of these parameters may depend on the electrode geometry and the frequency f used for the measurement₁And f₂. Variations in electrode geometry, patient body parameters, connecting cables and frequency may require different ranges for the above values.

In some treatment procedures, contact impedance measurements or calculations (e.g., the magnitude | Z |, slope S, and/or phase P components of bipolar contact impedance) may "drift" over time as fluid is injected into a patient prior to or during the treatment procedure. Examples of fluids introduced during a preparatory treatment procedure or during a procedure include, for example, saline, an anesthetic (such as propofol), a blood diluent (such as heparin), or other physiological fluids. The fluid may be introduced through the treatment device (e.g., ablation catheter) itself (e.g., saline through an irrigation port) and/or through IV infusion (IV bags, tubing, and syringes) or other delivery mechanisms. The introduction of liquid over time may affect the resistivity and/or impedance of the blood over time, which in turn may affect contact impedance measurements or calculations determined by the contact sensing subsystem or module based on electrical measurements (e.g., voltage and current measurements or direct impedance measurements) over time between a pair of contact sensing electrodes (e.g., between a pair of electrode members or portions of a compound tip (e.g., high resolution or combination electrode) assembly described herein). If not accounted for or compensated for, drift over time due to changes in blood resistivity and/or impedance may affect the accuracy or reliability of the contact function or contact index determination (e.g., an indicator of contact quality, contact level, or contact status). For example, electrophysiological saline is electrically conductive, and thus as more saline is introduced into the vasculature, the patient's blood is diluted and the resistivity of the blood drops, causing the contact impedance measurement or calculation to drift over time. As a result, a correction to the contact function or algorithm may be desired to account for or compensate for drift, thereby improving the accuracy of the contact function or contact index determination or algorithm. For example, without compensation, even if the contact level (e.g., contact force) remains stable, drift may cause the contact indication determination (which may be determined based on a static threshold) to be substantially changed, thereby providing an inaccurate or unreliable contact level indication or evaluation output and misinterpreting the clinician as an actual contact level.

The infusion rate is typically not constant or varies linearly with time. Thus, according to several embodiments, a lookup table or setting formula based on flow rate and duration may not be reliably used. Changes in blood resistivity may also be affected by factors other than the introduction of liquid, and the techniques described herein for counteracting drift due to the introduction of liquid may also be used to account for changes in blood resistivity due to other factors, such as the patient's body temperature, fluctuations in metabolic rate, etc.

In some embodiments, a threshold in the contact function or algorithm (such as the threshold Z in the weighted contact function provided above)_max、|Z|_min、S_max、S_min、P_max、P_min) May advantageously be changed or adjusted from a constant value to a value that varies based on one or more reference measurements. For example, if contact impedance measurements are to be measured between a distal RF electrode member and a proximal RF electrode member of a high resolution or unitized electrode assembly (such as a split-tip electrode assembly) as described herein, which is likely to be in contact with target tissue such as cardiac tissue, a second set of reference measurements may be obtained between a different pair of reference electrodes in the blood pool but expected not to be in contact with tissue (or at least not in continuous contact with tissue). According to several embodiments, the impedance measurements or values determined from a pair of reference electrodes when in blood vary proportionally or substantially proportionally to the impedance measurements or values determined between contacting sensing electrodes (e.g., the electrode portions of a compound tip or unitized electrode assembly) when in blood or in contact with tissue. The impedance value determined from the reference electrode need not be the same as the impedance value of the contacting sensing electrode in an absolute sense. A correction factor or scaling value may be applied as long as the drift of the reference electrode tracks or otherwise indicates the drift of the contacting sensing electrode proportionally or substantially proportionally. In some implementations, the impedance value of the reference electrode drifts within ± 20% (e.g., within 20%, within 15%, within 10%, within 5%) of the impedance value of the contact sensing electrode. In some embodiments, a pair of reference electrodes may be positioned adjacent or near a target treatment site (e.g., an ablation site), but not in contact with tissue. In other embodiments, the pair of reference electrodes are not positioned adjacent to the target treatment site. In some casesIn an embodiment, the pair of reference electrodes are not positioned outside the patient and not within the medical device such that they cannot be exposed to blood.

Fig. 41A shows an ablation catheter having a compound tip (e.g., high resolution or combination) electrode assembly consisting of a distal electrode member D1 and a proximal electrode member D2, separated by a gap distance, and a distal ring electrode R1 and a proximal ring electrode R2, the distal ring electrode R1 and proximal ring electrode R2 being positioned at a distance along the ablation catheter proximal of the proximal electrode member D2 and separated from each other by a separation distance. In various embodiments, the separation distance between R1 and R2 (the distance between the proximal edge of R1 and the distal edge of R2) is between 0.5mm and 3.5mm (e.g., between 0.5mm and 1.5mm, between 1.0 and 3.0mm, between 1.5mm and 2.5mm, between 2.0mm and 3.5mm, overlapping ranges thereof, or any value within said range, including but not limited to 0.5mm, 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, and 3.5 mm). The separation distance between R1 and R2 (or other reference electrode group) may be the same as the gap distance between D1 and D2 (or other contact sense electrode group), and may be different from the gap distance between D1 and D2. The distance between the proximal edge of D2 and the distal edge of R1 can be in the range of from 1mm to 10mm (e.g., from 1.0mm to 2.0mm, from 2.0mm to 3.0mm, from 3.0mm to 5.0mm, from 4.0mm to 8.0mm, from 5.0mm to 10.0mm, overlapping ranges thereof, or any value within the stated range, including but not limited to 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm, and 5.0 mm.

In some embodiments, the ring electrodes R1, R2 are used for mapping or other functions in addition to being used for reference measurements. The ring electrodes R1, R2 (which are spaced proximally of the distal tip of the ablation catheter) tend not to be in contact with the tissue (or at least not in continuous contact with the tissue), but rather are in the blood/fluid mixture within the chamber, cavity, space or vessel of the heart, other organ, or vasculature adjacent to (e.g., near or adjacent to) the target tissue being treated. Thus, the measurements obtained by the ring electrodes R1, R2 may be used as valid reference measurements that may be used to track changes in impedance of the blood (and thus to adjust the impedance measurements or calculations (e.g., amplitude, slope, and/or phase) used in the qualitative contact assessment function or algorithm) as saline or other liquid is infused over time, thereby improving the accuracy and/or reliability of the qualitative contact assessment function or algorithm. In some embodiments, the reference measurements may be obtained over a period of time, and the smallest measurement value may be selected as the reference measurement to account for possible conditions over the period of time when one or both of the ring electrodes are in contact with tissue (e.g., when the ablation catheters are in a parallel or substantially parallel orientation). The ablation catheter may include any of the structures or features described herein (e.g., a filtering element and/or a spacing between D1 and D2 electrode members for facilitating high-resolution mapping and ablation RF energy delivery, a plurality of distributed temperature measurement devices or sensors, a thermal shunt structure, an irrigation outlet, etc.).

Fig. 41B schematically illustrates an embodiment of the electrode members D1, D2 of the high resolution or unitized electrode assembly of the ablation catheter of fig. 41A, as well as the electrical circuit connections between the ring electrodes R1, R2 and a contact sensing system or module such as described herein. The contact sensing system or module may be housed, embodied, or stored in a separate component, either within the energy delivery module 40 (e.g., RF generator) or within the ablation catheter itself. As shown in fig. 41B, the circuit may include switches SW1, SW2 to switch or toggle the connection between the electrode members D1, D2 and the ring electrodes R1, R2 for reference measurement to the touch sensing system or module. Other alternative connection implementations may be used as desired and/or required.

As one example, when a pair of proximal ring electrodes is used to obtain a reference impedance measurement, | Z | Y |, as shown below, may be pair_maxThreshold application correction:

|Z|_{max_adj}＝|Z|_max*(1–A*(Z_{R1R2_initial}-Z_{R1R2_current}))，

wherein | Z |_maxIs a baseline threshold that is effective in the absence of infusion of saline or other fluid, Z_{R1R2_initial}Is based on a ringInitial baseline impedance value, Z, determined by one or more electrical measurements between electrodes R1 and R2_{R1R2_current}Is a current impedance value determined from one or more electrical measurements between ring electrodes R1 and R2, and a is a scaling factor.

A similar concept can be applied to | Z_minThreshold value:

|Z|_{min_adj}＝Z_min*(1–B*(Z_{R1R2_initial}-Z_{R1R2_current}))，

wherein Z_minIs a baseline threshold, which is effective in the absence of saline infusion, Z_{R1R2_initial}And Z_{R1R2_current}As previously described above, and B is the scaling factor.

Examples of how such correction or compensation may be achieved by the contact sensing subsystem or module (e.g., upon execution of specific program instructions stored in memory by one or more processors) are presented below with respect to an example benchmarking (bench) test, in which salinity levels are adjusted over time. For simplicity, only the magnitude portion of the contact function will be described, denoted as CF 1. However, the same concept can also be used to compensate for drift in slope or phase response when injecting a liquid into a patient.

Table 2 below shows that in a practical benchmark test of contact force of 5g to cardiac tissue, | Z_f1And response of CF1 to salinity level:

table 2 CF 1a constant force of 5g was applied in response to increasing salinity level.

As can be seen in Table 2, as the salinity level exceeds the baseline (salinity level 1), the amplitude | Z_f1Begins to fall and CF1 begins to fall-indicating a reduced contact, although the contact force remains constant at 5 g.

Table 3 below shows how drift correction may be applied to account for this effect caused by changes in salinity levels that may occur due to the introduction of liquid over time.

Table 3 responses of CF1 and CF1_ adj with drift correction.

In this embodiment, the reference measurement Z_{R1R2_current}For calculating | Z_{max_adj}And | Z |)_{min_adj}. In this embodiment, | Z_{max_adj}Is calculated as Z_max*(1–A*(Z_{R1R2_initial}-Z_{R1R2_current}) And | Z | O_{min_adj}Is calculated as Z_min*(1–B*(Z_{R1R2_initial}-Z_{R1R2_current})。|Z|_{max_adj}And | Z |)_{min_adj}These values of (a) are then used to calculate a drift corrected value of CF1, denoted CF1_ adj. As shown in table 3, the response of CF1_ adj remained consistent as salinity levels increased over time.

The above technique is an example of how drift correction can be applied to impedance magnitude measurements or calculations when liquid is injected into a patient over time. The same concept can also be used to compensate for drift in slope or phase response when injecting fluid into a patient over time. To correct for slope or phase response, the amplitude measurement between ring electrodes R1 and R2 can be used in the same manner as described above. Additionally, drift correction may be created using measured or calculated slope or phase responses on the ring electrodes R1 and R2.

According to several embodiments, instead of using ring electrodes R1 and R2 for reference measurements, the electrode members D1 and D2 of the high resolution or unitized electrode assembly may be periodically pulled to a non-contact position for reference measurements. Other combinations of electrode pairs on the ablation catheter other than two ring electrodes may be used to obtain reference measurements (e.g., R1 and D2, R1 and D1, R2 and D1, or R2 and D2). The reference measurements may also be obtained from other measurement devices or sources, as desired and/or required. For example, the reference measurements may be obtained from a separate device (infusion, diagnostic catheter, mapping catheter, coronary sinus catheter, etc.) other than the ablation catheter. The same drift correction methods or techniques described above when using ring electrodes for reference measurements may be similarly applied to reference measurements obtained by the electrode members D1 and D2 of the high resolution or unitized electrode assembly or from any other electrode or other measurement device or source. The drift correction techniques described herein may be applied to contact sensing measurements or values obtained or determined by any pair of electrodes or electrode portions or other contact assessment means using a reference measurement or value obtained or determined by another pair of electrodes or electrode portions or other contact assessment means. The electrode pairs or electrode portion pairs may be replaced with a single member or with more than two members (e.g., three, four, five, six members). For example, although a two-electrode impedance measurement technique is described, a three-electrode or four-electrode impedance measurement technique may be applied with equivalent results.

A method of correcting drift in contact impedance measurements or calculations (e.g., amplitude, slope, and/or phase components of bipolar contact impedance measurements or calculations) includes determining at least one reference impedance value that can be used to adjust corresponding threshold impedance component values of a contact quality assessment function (e.g., a contact function described herein) over time. For example, at least one reference impedance value may be determined from electrical measurements obtained using a pair of electrodes that are unlikely to be in contact with tissue but are likely to be in contact with a blood/liquid mixture proximate to the electrode or electrode portion being used to obtain contact impedance measurements for use in a contact quality assessment function or contact indication algorithm (such as those described herein), thereby providing a measurement that may be used to adjust the contact impedance component measurements to increase the accuracy and/or reliability of the contact quality assessment function or contact indication algorithm. In some embodiments, at least one reference impedance value may be obtained for each threshold impedance component of the contact quality assessment function or contact indication algorithm (e.g., the amplitude at the first frequency, the slope between the amplitude at the first frequency and the amplitude at the second frequency, and the phase at the second frequency). The method may further include adjusting the threshold impedance component values based on the reference measurement(s). The adjustment may be performed continuously over time or at predetermined time intervals (e.g., every tenth of a second, every half of a second, every two seconds, every three seconds, every four seconds, every five seconds, every ten seconds, every fifteen seconds, every twenty seconds).

The method may further include using the adjusted threshold impedance component value in a contact quality assessment function or a contact indication algorithm instead of the threshold impedance component value actually measured by the electrode or electrode portion in contact with the tissue. The method may be performed automatically by a contact sensing subsystem or module not apparent to a clinical professional (which may include, for example, program instructions stored on a non-transitory computer-readable medium that may be executed by one or more processing devices and/or may include hardware devices such as one or more microprocessors or central processing units, memory (RAM or ROM), integrated circuit components, analog circuit components, digital circuit components, and/or mixed signal circuits).

In some embodiments, the contact function or contact criteria may be determined based at least in part on "if-then" case condition criteria. An example of an "if-then" case criterion is replicated here:

fig. 32 shows an embodiment of a contact criteria procedure 5100 corresponding to the "if-then" case condition criteria above. Contact criteria procedure 5100 may be executed by a processor and stored in memory orInstructions in a non-transitory computer readable storage medium. At decision block 5105, the measured or calculated impedance magnitude value (e.g., based on a direct impedance measurement or based on a voltage and/or current measurement obtained by a unitized electrode assembly comprising two electrode portions) is compared to a predetermined threshold impedance. If the measured or calculated impedance magnitude | Z_MAG| is greater than a first threshold value Z_THR1(e.g., 350 Ω), the touch criteria (CC) is assigned as "best (best)" or highest value. However, if the measured or calculated impedance magnitude value | Z_MAG| is less than threshold value Z_THR1Process 5100 proceeds to block 5110 where various sub-values of impedance magnitude, slope and phase are determined in block 5110. At block 5115, the individual sub-values are combined (e.g., summed) into a total value indicative of the contact state. In some embodiments, the combination is the sum of weighted combinations, as described above.

Process 5100 may optionally generate an output at block 5120. For example, if at decision block 5105, the measured or calculated impedance magnitude value | Z_MAG| is greater than a first threshold value Z_THR1The process may show the user an alert that further manipulation of the catheter or other medical instrument may not further improve tissue contact, but may compromise patient safety. For example, if the user pushes too hard on a catheter or other medical instrument, the additional pressure may have little improvement in tissue contact, but may increase the risk of tissue perforation (e.g., heart wall perforation). The output may include a qualitative or quantitative output as described in further detail herein (e.g., in connection with fig. 33).

FIG. 32A shows the measured or calculated impedance magnitude value | Z_MAG| is less than a first threshold value Z_THR1An embodiment of the various sub-value sub-processes 5110 of the executed process 5100. By varying the impedance magnitude (| Z)_MAG|), slope (S) and phase (P) are divided into intervals corresponding to good (good), medium (medium), low (low) and no-contact (no-contact) levels to calculate a Contact Criterion (CC) total value. Determining a good, medium, low for each of the impedance magnitude, slope, and phase components depending on a comparison to various predetermined thresholdsOr does not touch the corresponding sub-value. The sub-values may be combined to determine an overall contact state value. In the example case condition criteria above, CC is three parameters (| Z)_MAGI, S, P) is a sum of the respective values received for each parameter according to its corresponding contact level (e.g., good, medium, low, or no contact). For example, if Good (Good) is 3, Medium (Medium) is 2, Low (Low) is 1, and No Contact (No _ Contact) is 0, the total CC may be in the range of 0-2 for No or Low Contact, 3-4 for poor Contact, 5-6 for Medium Contact, and 7-9 for Good Contact. In one embodiment, when | Z_MAGI exceeds a first threshold value Z_THR1When CC is 10, it is an indication that the "best" or "optimal" tissue contact level is reached. Other intervals or numbers may be used as desired.

In some embodiments, more than two frequencies (e.g., three or four frequencies) are used for tissue contact or tissue type detection. Although the above calculations are presented using impedance magnitude, slope and phase, other characteristics of the complex impedance may be used in other embodiments. For example, analysis of the real and imaginary components of the impedance may be used. Analysis of admittance (acceptance) parameters or scattering parameters may also be used. In some embodiments, direct analysis of the voltages and currents described in FIGS. 25A-27 (e.g., processing of voltage or current amplitudes, frequency variations, or relative phases) may be used. The analysis of the voltage or current may be performed in the time domain or the frequency domain. The impedance measurements or values may be calculated based on the voltage and current measurements, or may be measured directly. For example, the phase measurement may include a phase difference between the measured voltage and the measured current, or may be an actual impedance phase measurement.

In some embodiments, the contact indicator or contact function is associated with an output via an input/output interface or device. The output may be presented for display on a graphical user interface or display device communicatively coupled to the contact sensing subsystem 50 (fig. 1). As shown in fig. 33, the output may be qualitative (e.g., relative contact levels as represented by color, scale, or gauge) and/or quantitative (e.g., as represented by a graph, rolling waveform, or numerical value).

Fig. 33 illustrates an embodiment of a screen display 5200 of a graphical user interface of a display device communicatively coupled to the contact sensing subsystem 50 (fig. 1). The screen display 5200 includes a display shown at a frequency f₁A graph or waveform 5210 of the impedance magnitude as a function of time is shown, and a block 5211 indicating a real-time value of the impedance magnitude. The screen display 5100 also includes a slope (from f) over time₂To f₁) A graph or waveform 5220 and a block 5221 indicating a real-time value of the slope. The screen display 5200 further includes a display shown at a frequency f₂A plot or waveform 5230 of the phase as a function of time, and a block 5231 indicating a real-time value of the phase. As described above, the three measurements (amplitude, slope, and phase) are combined into a touch function and may be expressed as a touch function or indicator that varies over time, as shown on the graph or waveform 5240. Real-time or instantaneous values of the contact function may also be displayed (block 5241).

In some embodiments, as shown in fig. 33, the contact function or indicator may be represented as a virtual gauge 5250, which virtual gauge 5250 provides a qualitative assessment (alone or in addition to a quantitative assessment) of the contact status or level of contact in a manner that is readily discernable by the clinician. The gauge 5250 may be divided into, for example, four segments or regions representing different categories or characterizations of contact quality or contact status. For example, a first segment (e.g., contact function value from 0 to 0.25) may be red and represent no contact, a second segment (e.g., contact function value from 0.25 to 0.5) may be orange and represent a "light" contact, a third segment (e.g., contact function value from 0.5 to 0.75) may be yellow and represent a "medium" or "moderate" contact, and a fourth segment (e.g., contact function value from 0.75 to 1) may be green and represent a "good" or "firm" contact. In other embodiments, fewer than four segments or more than four segments (e.g., two segments, three segments, five segments, six segments) may be used. In one embodiment, three sections are provided, one for no or poor contact, one for medium contact, and one for good or firm contact. The segments may be equally divided or otherwise divided as desired and/or required. Other colors, patterns, graduations and/or other visual indicators may be used as desired. Additionally, a "contact alert" color or gauge scale may be provided to alert the user as to engaging a catheter or other medical instrument with too much force (e.g., a contact function value greater than 1). The gauge 5250 may include a pointer member for indicating the real-time or instantaneous value of the contact function on the gauge 5250.

In some embodiments, the qualitative indicator 5260 indicates that: whether the contact is sufficient to initiate a therapeutic (e.g., ablation) procedure, the level of contact, the type of tissue, and/or whether the contact is greater than desired for safety. The qualitative indicator 5260 can provide a binary indication (e.g., sufficient contact vs. insufficient contact, contact or no contact, ablated tissue or living tissue) or a multi-level qualitative indication, such as the multi-level qualitative indication provided by the gauge 5250. In one embodiment, the qualitative indicator 5260 displays a color on the gauge 5250 that corresponds to the current contact function value. Other types of indicators, such as horizontal or vertical bars, other meters, beacons, color cast indicators, or other types of indicators, may also be used with the touch function to communicate the quality of the touch to the user. The indicator may comprise one or more Light Emitting Diodes (LEDs) adapted to be activated upon contact (or a sufficient level of contact) or loss of contact. The LEDs may have different colors, where each color represents a different level of contact (e.g., red for no contact, orange for poor contact, yellow for medium contact, and green for good contact). The LED(s) may be positioned on the catheter handle, on a display or patient monitor, or on any other separate device communicatively coupled to the system.

In one embodiment involving the delivery of radiofrequency energy using a radiofrequency ablation catheter having a plurality of temperature measurement devices (such as the ablation catheter and temperature measurement devices described herein), the criteria for detecting loss of tissue contact during delivery of radiofrequency energy may be implemented as:

ΔT_i/Δt<threshold 1 (condition 1)

ΔT_comp/ΔP<Threshold 2 (Condition 2)

Wherein Δ T_iIs a change in temperature of any of a plurality of temperature measurement devices (e.g., sensors, thermocouples, thermistors) positioned along a catheter or other medical instrument; Δ t is the time interval over which the temperature change is measured; delta T_compIs the maximum temperature change in the temperature of the temperature measurement device, and Δ P is the change in applied power.

Condition 1 may indicate that the temperature measurement obtained by the temperature measurement device drops rapidly over a short period of time, which may indicate loss of contact or an insufficient or insufficient level of contact. For example, if Δ T is within Δ T of 1 second_iIs-10 degrees celsius and the threshold 1 is-5 degrees celsius/second, the loss of contact condition is met (because-10 degrees celsius/second<-5 degrees celsius/second).

Condition 2 can be illustrated: even if sufficient power is applied, the temperature of the temperature measurement device does not increase, which may indicate loss of contact or insufficient levels of contact. For example, if Δ T_compAt 5 degrees celsius and Δ P at 30 watts, and if the threshold 2 is 1 degree celsius/watt, the loss of contact condition is met (because of 5 degrees celsius/30 watts)<1 degree celsius/watt).

Electrical measurements (e.g., impedance measurements such as impedance magnitude, impedance phase, and/or slope between impedance magnitudes at different frequencies) obtained by a contact detection subsystem or module (which may, for example, be within energy delivery module 40, such as a radiofrequency generator unit, or may be separate stand-alone components) may be affected by hardware components in a network parameter circuit (e.g., impedance circuit) or network located between the contact sensing subsystem or module and electrodes D1, D2 of a high resolution electrode assembly or split-tip electrode assembly of an ablation catheter or other therapeutic device. For example, different types (e.g., branding, lengths, materials) of cables or wires may have different network parameters and/or other parameters that affect electrical measurements differently (e.g., voltage, current, and/or impedance measurements), or the wrapping of the cables or wires may affect electrical measurements. Additionally, in some implementations, the catheter interface unit may be connected at some point along the network parameter circuitry between the contact detection subsystem or module (e.g., contact detection subsystem module) and the electrodes or electrode portions D1, D2 of the high resolution electrode assembly or split-tip electrode assembly of the energy delivery catheter or other therapeutic device (or may reside in the electrical path between the contact detection subsystem or module (e.g., contact detection subsystem module) and the electrodes or electrode portions D1, D2 of the high resolution electrode assembly or split-tip electrode assembly of the energy delivery catheter or other therapeutic device). The catheter interface unit may or may not include filters (e.g., low pass filters, band pass filters, high pass filters implemented in hardware or software) adapted for filtering signals having various frequencies. As one example, the catheter interface unit may include a hardware module or unit adapted to facilitate connection of both the radio frequency generator and the electroanatomical mapping system to a high resolution mapping and energy delivery catheter (device, such as an ablation catheter or other energy delivery and temperature measurement device described herein) having multiple electrode portions or members, connected or otherwise residing in the circuit path of the separate electrode members at some point along a network parameter circuit (e.g., impedance measurement circuit), the presence or absence of the catheter interface unit or other hardware module or unit, or differences in network parameters of the cables, generators, or wires used, may result in changes in the network parameters (e.g., scattering parameters or electrical parameters, such as impedance measurements directly dependent on or from voltage and current measurements) or may result in changes in the network parameters (e.g., electrical measurements or values, such as impedance measurements or values) do not accurately reflect the actual network parameter values (e.g., impedance) between the two electrodes of the high-resolution electrode assembly, resulting in less accurate and/or inconsistent values of the contact indication. Thus, lack of accuracy or consistency can have adverse effects on treatment outcomes or parameters, and can have deleterious consequences related to safety and/or efficacy. Accordingly, several embodiments are disclosed herein to improve the accuracy and consistency of network parameter values (e.g., electrical measurements such as impedance magnitude, slope or phase values or voltage or current measurements) obtained by ablation systems including unitized electrode assemblies (e.g., high resolution or split tip electrode arrangements of spaced-apart electrode members or portions).

According to several embodiments, systems and methods are provided for de-embedding, removing, or compensating for effects caused by changes in cables, generators, wires, and/or any other component of an ablation system (and/or a component operably coupled to ablation) or by the presence or absence of a catheter interface unit or other hardware component in an energy delivery and mapping system. In some embodiments, the systems and methods disclosed herein advantageously result in a contact indicator value based on a network parameter value (e.g., impedance value) that more closely represents the actual network parameter value (e.g., impedance) across the electrodes of a high resolution electrode assembly. Thus, as a result of the compensation or calibration systems and methods described herein, the clinician may be more confident that the contact indication values are accurate and not affected by variations in the hardware or equipment used in or connected to the system or network parameter circuit. In some arrangements, the network parameter values (e.g., impedance measurements) obtained by the system using the compensation or calibration embodiments disclosed herein may be within ± 10% (e.g., within ± 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%) of the actual network parameter values (e.g., impedance values) across the electrode members of the unitized electrode assembly. For example, using this method, the impedance magnitude, impedance slope (the ratio of the impedance magnitudes at two frequencies), and phase of the impedance can each be measured individually to within +/-10% or better. As a result, the contact function or contact indicator may advantageously provide an accurate representation of tissue contact with an accuracy of +/-10% or more.

Fig. 34A shows a schematic block diagram of an embodiment of a network parameter measurement circuit 5400 (e.g., a tissue contact impedance measurement circuit). The network parameter measurement circuit 5400 includes a contact sensing signal source 5405, two high resolution electrode assemblies at the distal portion of the ablation catheterA load 5410 between electrodes D1, D2, and a chain representing a plurality of two-port networks of generator 5415, catheter interface unit cables 5420A, 5420B, catheter interface unit 5425, generator cable 5430, and catheter wires 5435. Because in certain arrangements, network parameter values (e.g., scattering parameters or electrical measurements, such as voltage, current, or impedance measurements) are obtained at the generator 5415 level at the beginning of the chain, the measured network parameter values (e.g., impedance values obtained directly or from voltage and/or current values) may differ significantly from the actual network parameter values (e.g., impedance values) between the two spaced-apart electrode members D1, D2 due to the effects of components of the network parameter circuit between the signal source 5405 and the electrode members D1, D2. The impedance values may include impedance magnitudes, slopes between impedance magnitudes at different frequencies, and/or impedance phase values. For example, at frequency f₁The detected impedance magnitude of (d) may be related to at frequency f₁The actual impedance magnitudes at (c) differ by ± 25%. Similarly, the detected slope (at frequency f)₂And f₁The ratio of the impedance magnitudes below) may differ by ± 50% from the actual slope. Furthermore, the detected phase may be + -30 degrees from the actual phase. Due to inaccuracies of these combinations, the Contact Function (CF) or contact indication value may differ from the expected contact function or contact indication value by-100% or + 150%, thereby making the contact function ineffective in determining tissue contact. According to several embodiments, the compensation or calibration embodiments disclosed herein may advantageously improve the accuracy of the contact function or contact indication value.

Network parameters for each of the multi-port (e.g., two-port) networks in the network parameter measurement circuit 5400 can be obtained (e.g., measured) and used to convert measured network parameter values (e.g., scattering parameters or electrical parameters, such as impedance) to corrected (actual) values (e.g., impedance values). In some embodiments, a two-port network analyzer is used to directly measure scattering parameters (S-parameters) at the input and output of each of the two-port networks. In other embodiments, multiple components of the network parameter measurement circuit 5400 may be combined into a group of components and measured together. The network parameters for each component or group of components may be combined to determine the combined impact of the two-port network chain on the network parameter value(s). In some implementations, the scattering parameters of at least some of the components may be hard-coded into a software program (e.g., using an average based on some measurement samples) in order to reduce the number of measurements to be made or obtained.

According to one implementation, the S-parameter matrix for each of the two-port networks or two-port network groups may be converted to an overall transmission matrix. The overall transmission matrix may then be converted back to S-parameters (or some other parameters) to generate an S-parameter matrix (or another type of matrix) for the entire network. The S-parameters from the measured input reflection coefficients can then be de-embedded, calibrated, or compensated using the S-parameters from the overall S-parameter matrix to yield corrected (actual) reflection coefficients. The actual reflection coefficient may then be converted into a corrected impedance value that more closely indicates the actual impedance between the two electrode portions D1, D2 of the high resolution electrode assembly. In several embodiments, the corrected impedance value is used as an input to a Contact Function (CF) or other contact indication or contact level assessment algorithm or function as described above. For example, the corrected impedance values may be used to determine Z, S and the P value in the weighted Contact Function (CF) described above.

The effects of the hardware components of the network parameter measurement circuit (e.g., impedance measurement circuit) 5400 can be compensated, de-embedded, or calibrated to reduce or eliminate the effects of or differences in the hardware components of the particular system (e.g., impedance measurement circuit) set prior to first use; however, when different hardware components are used (e.g., generators, cables, catheters, etc.) or when a catheter interface unit or other hardware component for facilitating electro-anatomical mapping is inserted or removed, the components of the network parameter circuit may differ in different courses, resulting in inconsistencies, if not compensated for. In some embodiments, the overall system S-parameter matrix may be updated only when a connection within the network parameter measurement circuit 5400 changes (e.g., when a catheter interface is inserted into or removed from an electrical path, when a cable is switched, etc.).

In some embodiments, instead of requiring manual de-embedding of the effects on the impedance of certain circuit components when a connection is changed, which can be time consuming and result in an increased likelihood of user error, network parameters of a subset of the various components (e.g., the generator 5415, the catheter interface unit cables 5420A, 5420B, and the catheter interface unit 5425) are automatically measured to enable the effects of these elements to be de-embedded or otherwise compensated or calibrated from the network parameters (e.g., scattering parameters or impedance measurements). Fig. 34B illustrates an embodiment of a circuit 5450 that may be used to automatically de-embed or compensate for the effects of certain hardware components in the network parameter circuit 5400. In one embodiment, the auto-calibration circuitry 5450 is located at the distal end of the catheter interface unit cable before the generator cable 5430 and the catheter wires 5435. The circuit 5450 may advantageously provide the following capabilities: the electrode members D1, D2 of the high resolution electrode assembly were disconnected from the generator cable 5430 and the catheter 5435, and a known load was connected between D1 and D2.

In this embodiment, the auto-calibration circuitry 5450 may assume that the network parameters of the generator cable 5430 and catheter wire 5435 components are known and may be assumed to be constant. However, if the generator cable 5430 and/or the catheter wire 5435 are determined to vary significantly from portion to portion, the circuitry 5450 may be implemented at the distal end of the generator cable 5430, in the catheter tip, or at any other location, as desired or required. In some embodiments, the known load of the auto-calibration circuit 5450 includes a calibration resistor R_calAnd a calibration capacitor C_cal. The switch can be used for connecting R_calConnected as a load with C_calConnected as a load, and R_calAnd C_calThe two are connected in parallel as a load. Other components (e.g., inductors, combinations of resistors, inductors, and/or capacitors, or short circuits or open circuits may be used as known loads). As shown in fig. 34B, the combined network parameters of the generator 5415, catheter interface unit cables 5420A, 5420B, and catheter interface unit 5425 are represented as a single combined network (network 1).

In this embodiment, the network parameter is usedThe way directly measures a network parameter (e.g., S-parameter) of the network 1 and creates an S-parameter matrix from the network parameter. Each of the elements in the S-parameter matrix is complex and frequency dependent. The S-parameter may be measured at a plurality of different frequencies (e.g. 3 different frequencies in the kHz range, such as a first frequency of 5-20kHz, a second frequency of 25-100kHz and a third frequency of 500-1000 kHz). In one embodiment, at resistor R_calIs connected with a capacitor C_calIn the case of being disconnected, in the capacitor C_calIs connected with a resistor R_calIn case of disconnection and in case of resistor R_calAnd a capacitor C_calThe complex impedance is measured with both connected in parallel. The relationship between the measured complex impedance, the S-parameters of the network 1 and the known load may be expressed as three equations which may then be used to solve for the S-parameters of the network 1. Once the S-parameters are characterized, they can be combined (e.g., using a transmission matrix approach) with the known network parameters of the generator cable 5430 and catheter wires 5435 to provide a corrected (actual) impedance measurement at the distal portion of the catheter (e.g., across two spaced apart electrode portions of a unitized electrode assembly).

The automated calibration techniques and systems described herein advantageously allow for increased confidence in contact indication values regardless of the generator, cable, catheter or other equipment used, and regardless of whether hardware components (e.g., catheter interface units) are connected to facilitate simultaneous electroanatomical mapping. The various measurements may be performed automatically upon execution of instructions stored on a computer-readable storage medium that are executed by a processor, or may be performed manually.

The automatic calibration systems and methods described herein may also be implemented using equivalent circuit models of one or more hardware components of the system (e.g., generator circuitry, cable and conduit wiring). In such implementations, the equivalent circuit model includes one or more resistors, one or more capacitors, and/or one or more inductors that approximate the actual response of the represented one or more hardware components.As an example, the generator cable assembly 5430 may be represented by a transmission line equivalent RLC model as shown in fig. 34C, where the impedance Z is_measWill be performed at port 1, while the desired actual (corrected) impedance Z is_actAt port 2. In this example, if the impedance measurement circuit is measuring the impedance Z_measThe actual impedance measurement Z may then be extracted by using circuit analysis techniques_act. The equations relating to the two impedances are given by:

r, L and C may be extracted from the network parameter measurements. For example, if we measure the impedance (Z) parameter of the network, we can derive the following relationship:

Z₁₁-Z₂₁＝R+jωL

where 1 and 2 denote port numbers of the circuit, and V₁、I₁、V₂And I₂Representing the voltage and current at each of the respective ports. The values of R, L and C can also be measured using a measurement tool (e.g., a multimeter). The equivalent circuit model approach described above is one example of this concept. In other implementations, more complex circuit models may be utilized to represent various elements of the system.

According to some arrangements, the high resolution tip electrode embodiments disclosed herein are configured to provide local high resolution electrograms (e.g., electrograms with highly increased local specificity due to the separation of the two electrode portions and the high thermal diffusivity of the material of the separator, such as industrial diamond). The increased local specificity may make the electrogram more sensitive to electrophysiological changes in the underlying cardiac or other tissue, so that the effect of RF energy delivery on cardiac or other tissue can be seen more quickly and accurately on high resolution electrograms. For example, an electrogram obtained using a high resolution tip electrode may provide electrogram data (e.g., graphical output) 6100a, 6100b, as shown in fig. 35, according to embodiments disclosed herein. As depicted in fig. 35, the local electrograms 6100a, 6100b generated using the high resolution tip electrode embodiments disclosed herein comprise amplitudes a1, a 2. The

With continued reference to fig. 35, according to some embodiments, the amplitudes of the electrograms 6100a, 6100b obtained using the high resolution tip electrode system may be used to determine whether the target tissue adjacent to the high resolution tip electrode has been sufficiently ablated or otherwise treated. For example, according to some configurations, the amplitude a1 of the electrogram 6100a of untreated tissue (e.g., tissue that has not been ablated or otherwise heated to a desired or required threshold, etc.) is greater than the amplitude a2 of the electrogram 6100b that has been ablated or otherwise treated. Thus, in some embodiments, the amplitude of the electrogram may be measured to determine whether the tissue has been treated (e.g., treated to a desired or required level according to a particular treatment regimen). For example, an electrogram amplitude a1 of untreated tissue in the subject may be recorded and used as a baseline. Future electrogram amplitude measurements may be obtained and compared to the baseline amplitude in an attempt to determine whether tissue has been ablated or otherwise treated to a sufficient or desired degree.

In some embodiments, a comparison is made between such baseline amplitude (a1) relative to the electrogram amplitude (a2) at the tissue location being tested or evaluated. The ratio of a1 to a2 can be used to provide a quantitative measure for assessing the likelihood that ablation has been completed. In some arrangements, if the ratio (i.e., a1/a2) is above some minimum threshold, the user may be notified that the a2 amplitude harvested tissue has been properly ablated. For example, in some embodiments, sufficient ablation or treatment may be confirmed when the a1/a2 ratio is greater than 1.5 (e.g., 1.5-1.6, 1.6-1.7, 1.7-1.8, 1.8-1.9, 1.9-2.0, 2.0-2.5, 2.5-3.0, values in between the foregoing, greater than 3, etc.). However, in other embodiments, confirmation of ablation may be obtained when the ratio of A1/A2 is less than 1.5 (e.g., 1-1.1, 1.1-1.2, 1.2-1.3, 1.3-1.4, 1.4-1.5, values in between the foregoing, etc.).

According to some embodiments, data related to tissue ablation or other tissue heating or treatment and collected, stored, processed, and/or otherwise obtained or used by an ablation system may be integrated with data obtained by one or more other devices or systems (such as, for example, a mapping system). As used herein, data is a broad term and includes, but is not limited to, numeric data, textual data, image data, graphical data, unprocessed data, processed data, and the like. As discussed in more detail herein, such integration of data may be used to advantageously provide useful information to a physician or other user (e.g., via a monitor or other output). For example, certain data may be configured to be displayed in association with various ablation or other heating points or locations that may be visually delineated on a model of a target region of the subject's anatomy (e.g., atrium, other chambers or locations of the heart, other tissues or organs, etc.). In some embodiments, such a model includes a three-dimensional rendering of the anatomical structure or other model, which is generated at least in part by the mapping system. As used herein, a mapping system is a broad term and includes, but is not limited to, three-dimensional (3D) electroanatomical navigation systems, rotor mapping systems, other types of navigation and/or mapping devices or systems, imaging devices or systems, and the like.

According to some embodiments, a mapping system (e.g., a 3D electro-anatomical navigation system, another type of device or system configured to generate a model of an anatomical structure surrounding a particular anatomical location, etc.) is configured to receive data and other information related to an ablation process from a separate ablation or tissue treatment device or system (e.g., a catheter-based RF ablation system, as disclosed herein) and/or any other type of mapping device or system configured to facilitate a treatment process (e.g., a rotor mapping system, another imaging or mapping device, any other electrophysiology device or system, etc.). However, in other embodiments, the ablation device or system is configured to be integrated with the mapping system and/or one or more other mapping or other devices or systems, as desired or required.

In embodiments where the mapping system is separate and distinct from the ablation device or system and/or any other device or system, the mapping system may be configured to be integrated with such other device or system. For example, in some embodiments, a mapping system (e.g., an electroanatomical navigation system) may be designed and otherwise adapted to receive data from a processor of a generator, other energy delivery module, and/or any other component of an ablation system. Thus, the mapping system may include one or more processors, ports (e.g., for hard-wiring to and integration with a separate device/system), wireless components (e.g., for hard-wiring to and integration with a separate device/system), filters, synchronization components or devices, and so forth. In some arrangements, a mapping system (e.g., a 3D electro-anatomical navigation system) may be configured to work with two or more different ablation devices or systems, as desired or required.

According to some embodiments, any of the ablation devices and systems disclosed herein, or an equivalent thereof, may be configured to provide information to a user regarding one or more completed ablations (e.g., ablation occurrences, spots (spots), or locations) along a target anatomy of a subject (e.g., cardiac tissue). Such ablation data may include, but is not limited to, temperature, power, electrode orientation, electrode-tissue contact quality or quantity (e.g., contact index or contact force), and the like. May be via integration into an existing mapping system (e.g., EnSite by jude Medical, inc^TMVelocity^TMCardiac mapping system, Biosense Webster Inc

3EP System, Rhythmia by Boston Scientific^TMA mapping system,Any other electro-parabolic navigation system, etc.) to provide such ablation data. For example, in some arrangements, information collected by an ablation system during an ablation procedure may be processed and integrated with mapping data (e.g., graphical output) of a separate 3D electroanatomical navigation system or other mapping system. In some embodiments, the graphical output of the separate mapping system may be configured to create and display a three-dimensional model of the targeted anatomical region (e.g., pulmonary veins, atria, other chambers of the heart, other organs, etc.), the electrodes and the catheter itself, the location at which ablation is performed, and so forth. In other embodiments, the combined data is displayed on a monitor that is separate and distinct from any portion or component of a separate mapping system. For example, the combined model or other graphical or textual representation may be configured to be depicted on a display or output of the ablation system, a completely separate monitor or output device (e.g., a device in data communication with the mapping system and/or the ablation system).

In an arrangement where a mapping system having a graphical user interface or other graphical output (e.g., which determines the 3D position of a catheter or electrode and creates a three-dimensional view of the target anatomical region to be treated) is separate from a system that receives, processes, stores, and otherwise manipulates data related to various ablations (e.g., ablation occurrences, points, locations, etc.) created by an ablation device (e.g., a catheter having RF electrodes), the two systems may be integrated or otherwise coupled to one another via one or more processors or control units. In some embodiments, such a processor or control unit may be included, at least in part, within the mapping system, within the ablation system, within both the mapping system and the ablation system, and/or within one or more separate devices or systems, as desired or required.

In some embodiments, the 3D location data, EGM activity data, rotor mapping data, ablation data, and/or any other data may be provided in a single, independent system configured to provide graphical output and other mapping data (e.g., EGM activity data, rotor mapping data, etc.) as well as ablation data within the same user interface. For example, in some arrangements, such a stand-alone system may be configured to provide graphical output and ablation data without integration or other manipulation of the data. In other words, in some embodiments, such a stand-alone system may be manufactured, assembled, or otherwise provided to a user in a ready-to-use design.

FIG. 36A shows one embodiment of a graphical output 7000 that is provided to a user via a monitor, another type of display, or any other output device. Such a monitor or other output device may be configured as part of an ablation system. Alternatively, the output device may be separate from the ablation system (e.g., a standalone device), or part of a separate mapping system (e.g., a 3D electroanatomical navigation system, other mapping devices or systems, etc.), another type of imaging or guidance system, or the like. In such a configuration, the output device may advantageously be configured to be operably coupled to an ablation system (e.g., a generator or other energy delivery module, a processor or controller, etc.).

As shown in fig. 36A, the tip or distal portion of the ablation catheter 7100 can be visible on a display or other output. As also shown in this embodiment, the various points along the target tissue (e.g., cardiac tissue) that have been ablated can be depicted as circles, points, or any other symbol or design. In some configurations, one or more other symbols or representations other than circles or dots may be used to represent locations where ablation or heating/treatment has been performed. For example, rectangles (e.g., squares), ovals, triangles, other polygons (e.g., pentagons, hexagons, etc.), irregular shapes, and the like may be used in addition to or in place of circles.

In some embodiments, as shown in fig. 36A, the monitor or other output 7000 may be configured to display the orientation of the body of the subject being treated via a graphical representation 7010 of the torso. Thus, the user performing the procedure may better visualize and understand the anatomical structure mapped and indicated on the output.

Any other information or data may be provided on output 7000 in addition to or instead of that depicted in fig. 36A. For example, in some embodiments, the information or data displayed on the output may include, but is not limited to, a date, time, duration, and/or other temporal information related to the procedure, a name and/or other information related to the subject being treated, a name and/or other information related to a doctor and/or others conducting or assisting the procedure, a name of the facility, and so forth, as desired or required.

According to some arrangements, as shown in fig. 36A and 36B, the graphical representation of the ablation 7200 displayed on the monitor or other output 7000 can help ensure that the physician accurately creates the desired ablation or heating/treatment pattern in the target anatomy. For example, in some embodiments, each ablation forms a circle or circular pattern around one or more pulmonary veins of the subject (e.g., around the ostium of a single pulmonary vein, around the ostia of two adjacent pulmonary veins, along the apical line (rooline) between adjacent ostia, etc.). In other embodiments, as discussed in more detail herein, the ablation pattern may be positioned along at least a portion of a heart chamber (e.g., an atrium) to disrupt an abnormal path along or near a pulmonary vein (e.g., along one or more ostia of the vein).

In some embodiments, information related to each ablation 7200 of a series of individual ablations included in an ablation procedure (e.g., ablation instance, occurrence, point, or location) may be provided to a user via monitor other output 7000. For example, when the user identifies a particular point or location, the user may be provided with information related to ablation 7200. For example, in some embodiments, information relating to ablation points or locations may be provided to a user by manipulating a mouse, touchpad, and/or other device on or near a particular ablation (e.g., a cursor or other pointing feature of such a device). In other embodiments, selecting a particular ablation may be accomplished by the user touching a particular portion of the touch screen with his or her finger. Regardless of how the user "selects" or otherwise "activates" a particular ablation, the output (and the corresponding device and/or system to which the output is operatively coupled) may be configured to provide certain data and/or other information related to the selected ablation. For example, as shown in fig. 37A, once a user "hovers" over a particular ablation 8202 or otherwise selects a particular ablation 8202, a separate window 8300 (e.g., a pop-up window or side window) may be displayed on monitor or other output 8000. Further, according to some arrangements, the separate window 8300 may fold or otherwise disappear once the user moves his or her cursor, finger, and/or other selection device or feature away from a particular ablation. In some embodiments, the pop-up window or separate window is configured to remain active or otherwise visible for a particular period of time after selection or activation (e.g., for 0.5 to 5 seconds, 5 to 10 seconds, longer than 10 seconds, a period of time between the aforementioned ranges, etc.), as desired or required. Advantageously, such a configuration may allow a user to quickly, easily, and conveniently view data and other information related to a procedure performed using the ablation system.

In some embodiments, the manner in which ablation data, electrical activity data (e.g., EGM activity data, rotor mapping data, etc.), and/or any other data are synchronized or linked to particular data may vary. For example, in some embodiments, ablation and/or other data may be captured during a time period (during the entire time period, at some point in time during the time period, a subset of times during the time period, etc.) during which ablation is occurring (e.g., during a time period in which energy is being delivered from a generator or other energy delivery module to an electrode of a catheter). In some configurations, for example, a physician (and/or another person assisting in a procedure, e.g., another physician, technician, nurse, etc.) can initiate and terminate such energy delivery via one or more controllers (e.g., foot pedals, hand-operated controllers, etc.).

Thus, according to some configurations, data from an ablation device or system (e.g., data captured, calculated, stored, and/or otherwise processed by a generator or other component of the ablation device or system), data from a separate mapping system (e.g., a device or system for obtaining and processing EGM activity data, rotor mapping data, etc.), and the like are automatically provided and synchronized to one or more processors of another mapping system (e.g., a 3D electro-throwing navigation system), as described herein. Such synchronization and integration may occur concurrently with the execution of the ablation procedure, or once the procedure has been completed, as desired or required.

However, in other embodiments, synchronization and integration of data between different devices and systems may be performed in other ways during or after execution of the ablation procedure. For example, the time logs between different devices and systems may be aligned to extract the necessary data and other information from the ablation system and/or any other separate system (e.g., a mapping system configured to obtain and process EGM activity data) to "match" or otherwise assign the necessary data to each ablation mapped by the ablation system (e.g., a 3D electroanatomical navigation system).

According to some arrangements, the data and other information provided to the user in the pop-up window on the display or other output device may be fixed or set by the manufacturer or vendor of the various components of the system (e.g., integrated mapping/ablation system, standalone 3D electroanatomical navigation system, etc.). However, in other embodiments, the data and information may be customized by the user as desired or required. Thus, the user may select a particular application or use desired data and information.

In some embodiments, as shown in the embodiment of fig. 37A, data and other information provided to a user by hovering over or otherwise selecting an ablation 8202 (e.g., in a pop-up window or other separate window 8300) may include, among other things: information (e.g., graphics, text, etc.) relating to the orientation of the electrode relative to the target tissue 8310, contact information 8320 (e.g., qualitative or quantitative output relating to the level of contact between the electrode and the tissue, as described in further detail herein), graphs or waveforms illustrating impedance measurements and determinations, slope measurements and determinations, phase measurements and determinations, contact indices or other calculations (e.g., based on various contact measurements such as, for example, amplitude, slope, and/or phase, etc.), temperature curves/profiles (e.g., temperature curves/profiles of the target tissue over time), electrogram amplitude reduction graphs and/or data (e.g., according to the configuration disclosed in fig. 35), and so forth, as desired or required.

With continued reference to fig. 37A, a pop-up or separate window 8300 associated with ablation 8202 includes a plot 8330 that plots tissue temperature (e.g., composite tissue temperature from various thermocouples or other temperature sensors at or near the electrodes), power, and impedance over time. As noted in more detail herein, such information (e.g., whether in graphical or textual form) may be valuable to a physician performing an ablation procedure. For example, a physician may quickly and conveniently hover over various ablations (e.g., ablation instances, points, or locations) 8200, 8202 to ensure that ablation of the target tissue has occurred according to his or her requirements and desires. In other embodiments, the pop-up or separate window 8300 may include one or more other graphs or graphs as desired or required by a particular user or facility. For example, in some embodiments, the window includes a map of temperature over time as detected by various thermocouples or other sensors located at or near the electrodes (see, e.g., fig. 22A, 22B, 23A, and 23B). In some embodiments, as shown in fig. 37A, the separate window 8300 may include time-varying temperature measurements along each of the proximal and distal thermocouples (or other temperature sensors) included with the electrode. As shown, the temperature data may be presented in graphical form to allow a practitioner to quickly and easily compare readings from different thermocouples. Such a profile (alone, or with other data and information provided via the graphical representation of the output device) may ensure that the practitioner maintains good awareness during the ablation process. For example, such a map of single thermocouple trends may allow a practitioner to assess whether desired or sufficient contact between the electrode and the target tissue was maintained during ablation. In some arrangements, for example, a review of a single thermocouple profile may infer clinical decisions such as the quality of tissue contact, whether and when loss of contact or displacement occurs, and so forth, as discussed in more detail herein. Thus, in some configurations, the system may alert the user (e.g., visually, audibly, etc.) to such displacement or any other potentially undesirable occurrence. In some embodiments, a separate display area, portion, or region 8350 (and/or any other portion or region) of the window 8300 may be provided along the pop-up window 8300 to provide additional data or information to the user, such as, for example, EGM activity data, rotor mapping data, additional temperature data, and so forth.

In some embodiments, a pop-up window or separate window 8300 may be customized by the user, as described herein. Thus, for example, a user may select (and modify between courses or over time) graphics, text, and/or other data and information displayed in the pop-up window 8300. In addition, various other features and characteristics related to the pop-up window may be modified. For example, the hover sensitivity of the system (e.g., how close a cursor, touch motion, or other selection method or technique needs to be to ablation to activate the pop-up window), whether the user needs to click on or otherwise manipulate a controller (e.g., a mouse button, press a touch screen, etc.) to activate the pop-up window, how long the pop-up window remains activated before disappearing from a monitor or other output device, the size, color, and/or other conventional display features (e.g., text font and size, color, etc.) of the graphical and/or textual information provided on the pop-up display, and so forth.

As described in more detail herein, in some embodiments, the contact function or indicator may be represented as a virtual gauge that provides a qualitative assessment (alone or in addition to a quantitative assessment) of the contact status or level of contact in a manner that is readily discernable by the clinician. Such gauges may be divided into, for example, four sections or regions representing different categories or characterizations of contact quality or contact state. For example, a first segment (e.g., with a contact function value from 0 to 0.25) may be red and represent no contact, a second segment (e.g., with a contact function value from 0.25 to 0.5) may be orange and represent a "light" contact, a third segment (e.g., with a contact function value from 0.5 to 0.75) may be yellow and represent a "medium" or "moderate" contact, and a fourth segment (e.g., with a contact function value from 0.75 to 0.75) may be green and represent a "good" or "firm" contact. In other embodiments, fewer than four segments or more than four segments (e.g., two segments, three segments, five segments, six segments) may be used. In one embodiment, three sections are provided, one for no or poor contact, one for medium contact, and one for good or firm contact. The segments may be equally divided or otherwise divided as desired and/or required. Other colors, patterns, graduations and/or other visual indicators may be used as desired. Additionally, a "contact alert" color or gauge scale may be provided to alert the user as to the engagement of a catheter or other medical instrument with too much force (e.g., a contact function value greater than 1). The gauge may include pointer members for indicating real-time or instantaneous values of the contact function on the gauge. Such gauges and/or other contact data and information may be displayed in the pop-up window 8300. The displayed contact index may be determined using the drift correction techniques described herein based on the reference measurement. Reference measurements and the times at which they were obtained may also be displayed.

In lieu of or in addition to the foregoing, additional data and/or information related to ablation may be displayed. For example, the data and/or information may include, but is not limited to: information related to the orientation of the electrode relative to the target tissue (e.g., graphics, text, etc.), temperature data (e.g., tissue temperature before, during, and/or after ablation, rate of change of tissue temperature during the course of ablation, etc.), contact information (e.g., qualitative or quantitative output related to the level of contact between the electrode and the tissue, whether contact with previously ablated or non-ablated tissue has been achieved, etc., as described in further detail herein), graphs or waveforms showing impedance measurements and determinations, slope measurements and determinations, phase measurements and determinations, textual measurements of impedance, contact indices or other calculations (e.g., based on various contact measurements such as, for example, amplitude, slope, and/or phase, etc.), temperature curves/profiles (e.g., time-varying temperature curves/profiles of the target tissue), electrode orientation during ablation, applied RF power statistics (e.g., maximum and average power), electrogram amplitude reduction maps and/or data, mapping images and/or data, heart rate, blood and other signs of the subject during a particular ablation, and the like.

According to some embodiments, individual ablations depicted on the monitor or other output may be represented by symbols (e.g., circles, rectangles, other shapes, etc.) configured to change in size (e.g., diameter, other cross-sectional dimensions), color, and/or in any other visually apparent manner based at least in part on one or more parameters associated with the ablation at the corresponding point or location. As an example, in some embodiments, when the first ablation is associated with a higher level of tissue ablation (e.g., a larger size (e.g., a deeper, longer, wider, larger area of action), a higher temperature of the ablated tissue, a longer duration of energy application, etc.), the diameter of the first ablation may be larger (e.g., proportionally or disproportionately) than the diameter of the second ablation. In some embodiments, the difference in size (e.g., diameter) of the various ablations is proportional to one or more ablation characteristics as listed above.

Another embodiment of a representation provided on a monitor or other output device 8000' is shown in fig. 37B. As shown, the target anatomical region to be treated has been mapped and delineated in the three-dimensional model. Further, various ablations 8200' that have been performed during the procedure may be shown relative to the mapped tissue. In the depicted embodiment, such ablations are numbered or otherwise marked (e.g., sequentially in the order of the ablations). However, in other arrangements, the ablation 8200' need not be marked. As shown in fig. 37B, in some configurations, ablation-related information (e.g., orientation, contact data, temperature profile, etc.) may be provided in a window or region 8300 'of the graphical representation 8000' that remains on the monitor throughout the course of treatment. Thus, in some embodiments, unlike the features of the representation discussed above with reference to fig. 37A, ablation-related data and other information is not provided in the pop-up window. In some embodiments, the data and other information provided in the window 8300 'relates to the particular ablation 8202' that a practitioner or other user has selected (e.g., via hovering, pressing a touch screen, and/or any other selection technique).

In some embodiments, as shown in fig. 38, graphical representations 9000 of various ablations 9400 depicted on a monitor or other output may include graphical and/or textual data configured to be always visible (e.g., for the duration of an entire procedure or at least for a relatively brief period of time longer than the pop-up window configurations disclosed herein). Such an arrangement can facilitate providing data and information related to two or more (e.g., some or all) ablations of an ablation procedure simultaneously to a physician or monitor or other viewer of other outputs of the graphical representation 9000. Thus, in some embodiments, a physician may conveniently and easily assess (e.g., via a single image, without requiring activation of a separate pop-up window, etc.) the status of an ablation procedure. Further, in some arrangements, the consistently presented data and information may assist the physician in identifying potential gaps in lesion formation (e.g., regions of target tissue that are not ablated or are under-ablated). As a result, the user may target these tissue regions to ensure a more complete and efficient ablation process.

With continued reference to fig. 38, the orientation of the electrodes (or other energy delivery members) positioned at each ablation along the distal end of the catheter 9100 relative to the skin can be shown in a single graphical representation 9000. As shown, in some arrangements, each ablation 9200 can include (e.g., within, adjacent to, etc.) one of three symbols 9400 that indicate whether the electrode is in a parallel, perpendicular, or oblique orientation relative to the tissue according to the various determination methods and techniques disclosed herein.

In some embodiments, each ablation 9200 shown in the graphical representation 9000 can include a shown treatment region 9500 that is proximate to a region or region of an ablation (e.g., an active ablation, an ablation that meets certain threshold requirements, etc.). For example, in some embodiments, such regions 9500 can identify portions of tissue along each ablation 9200 that are heated above a target temperature (e.g., 60 degrees celsius) or some other threshold temperature, which provides the physician with a degree of comfort to accomplish sufficient tissue heating as desired or required for a particular procedure or protocol. In some arrangements, the various treatment region representations 9500 can be color coded (e.g., yellow for low heat, orange for medium heat, red for high heat, etc.) to provide more detailed information to the physician. In other embodiments, such color coding may depend on the approximate and/or actual tissue temperature. Thus, the various treatment region representations 9500 associated with each ablation may be color coded (e.g., different colors, different shades (e.g., gray scale) or other color attribute levels, etc.) according to a temperature legend that may also be displayed.

Further note that fig. 38, regardless of whether or how the various treatment region representations 9500 surrounding the ablation 9200 are color coded or otherwise differentiated, the graphical representation 9000 can be configured to advantageously indicate regions or zones around the ablation 9200 or where the heating or ablation effect of adjacent ablations along the ablation 9200 is a composite. Alternatively, the estimate or determination of lesion depth, width, or volume may be plotted and displayed as part of a graphical representation or other output, as described in more detail herein (e.g., with reference to fig. 38 and 39). For example, in fig. 38, such a region or region 9500 of overlapping ablation/heating effect comprising two or more separate ablations 9200 is shown in darker color. As explained herein (e.g., with reference to fig. 38 and 39), overlap may be determined or estimated based on lesion depth, width, and volume estimates. In addition to or in lieu of that depicted herein, various other graphical representations may also be used to conveniently provide useful information to a physician or other user or viewer of such a system regarding a particular ablation procedure. Thus, as described above, the physician can better assess the status of the procedure and, if necessary, perform complementary well-targeted ablations to ensure successful results.

In some embodiments, the graphical representation may be configured to display a path of a desired or required ablation pattern. Such a path (not shown herein) may guide and otherwise assist the physician in following a predictable, safe, and efficacious ablation path as the ablation procedure is performed. In some arrangements, such desired paths may be shown as lines, points, and/or in any other manner that distinguishes such desired paths from other elements on the graphical representation 9000, as desired or required.

Fig. 39 shows a two-dimensional map of ablation depth over a particular ablation path. Such ablation depth data may be derived or estimated from electrode orientation, temperature, power, tissue contact information, and/or any other input. The depth and width of the lesion depends on electrode orientation, Temperature and power, and other factors, as discussed in "Three-Dimensional finite element Analysis of Current Density and Temperature distribution during radio Frequency Ablation" (IEEE-Dimensional FinitateElement Analysis of Current Density and Temperature distribution DuringAdo-Frequency Abslation ", volume 42, phase 9 (9 months 1995), pp.879-889, by Panescu et al, which is hereby incorporated by reference and made part of this specification. Thus, the graphical representation or other output 9600 may be configured to incorporate such data in order to map and estimate the lesion depth, width, or volume distribution, as desired or required. For example, in some embodiments, the ablation path may comprise a generally circumferential path around a pair of pulmonary veins (e.g., around the ostia of such veins) within the left atrium of the subject. In some arrangements, such ablation processes may help disrupt abnormal conduction patterns in subjects with atrial fibrillation or other arrhythmias, as is known in the art. Thus, in conjunction with or in lieu of ablation zone approximation determination (as shown in fig. 38), the system may be configured to determine (e.g., estimate according to various embodiments disclosed herein) an effective ablation or target heating depth, width, and/or volume along the heated tissue. As shown in the graphical representation 9600 in fig. 39, the system may show the ablation depth 9650 as a function of distance along the treatment path. Such information may be displayed (e.g., continuously, intermittently (e.g., as part of a pop-up window), etc.) with the overall ablation representation, as shown in fig. 37A or 37B or 38. Thus, a physician may be effectively provided with a three-dimensional assessment associated with the ablation process, wherein both the area/spatial extent and depth of ablation (or desired heating) of tissue are graphically represented to him or her during the surgical process. In other embodiments, a three-dimensional volumetric representation of ablated tissue may be provided to a user that graphically combines area range and depth into a single integrated image.

As described herein, regardless of how data and other information relating to a particular procedure is processed and displayed to a user, such embodiments may be advantageous in easily and conveniently assessing potential weaknesses in the procedure or clinically susceptible points or locations (e.g., identifying gaps along the tissue being treated). Thus, a physician or other user can use this valuable information to ensure that a more complete and thorough ablation procedure is performed consistently. As discussed herein, for example, with the various configurations disclosed herein, a physician can quickly identify a region of tissue along a desired ablation path that may not have been treated to a threshold level. Thus, such tissue regions may be targeted prior to completion of the ablation process to ensure proper and efficacious treatment.

According to some embodiments, the system may be configured to identify and highlight (e.g., automatically) potential or actual gaps (e.g., potential under-ablated or other vulnerable tissue regions) and identify (e.g., graphically, textually, etc.) such regions to the user. For example, in some embodiments, the system may highlight portions of the target anatomy that may not have been properly ablated (e.g., areas of insufficient length, width, depth ablated or heated relative to some threshold). Such highlighting may take any desired form, such as, for example, circling or otherwise drawing an outline around such regions, coloring these regions in different colors or other graphical patterns (e.g., cross-hatching), and so forth.

In some embodiments, the ability of the system to determine and indicate potential, possible, or actual lesion gaps (e.g., potential under-ablated regions of the subject's anatomy being treated) may help ensure that the practitioner is alerted to such locations. Thus, the physician can assess and determine whether any such regions exist and, if necessary (e.g., based on his or her expertise, experience, and general methodology), perform additional ablations at various locations before completing the treatment process. This can help ensure that the practitioner completes the ablation procedure consistently and reliably, which will increase the likelihood of clinical success.

In some embodiments, a mapping system (e.g., a 3D electro-anatomical navigation system) may be configured to map a heart chamber (e.g., an atrium) of a subject during a fibrillation (e.g., atrial fibrillation) treatment. For example, an electroanatomical navigation system or other mapping system may be configured to obtain EGM activity data, rotor mapping data, and/or other electrical data. As described herein, such data may be obtained from a mapping system that is also configured to obtain and process data that facilitates 3D mapping and modeling of a target anatomical location (e.g., the left atrium of a subject). Alternatively, such data may be provided to the mapping system (e.g., an electroanatomical navigation system) via a separate mapping device or system operably coupled to the mapping system, as desired or required

In some embodiments, a subject indicating atrial fibrillation exhibits an atrial fibrillation rotor pattern in its atria that is characteristic of the disease. In some arrangements, electrical mapping of signals transmitted through the atria of a subject, and thus more accurately determining a map of the corresponding atrial fibrillation rotor causing the disease, may aid in treating the subject. For example, in some embodiments, once the atrial fibrillation rotor is accurately mapped (e.g., using a separate mapping device or system integrated with or operably coupled to the 3D electro-anatomical navigation system), the practitioner may more accurately treat the portion of the atrium that helps treat the disease. This may provide several benefits to the subject, including more precise and accurate ablation that increases the likelihood of effective treatment, less trauma to the subject due to the area or volume of tissue that may be ablated, and so forth. Thus, in some embodiments, using the various embodiments described herein that provide detailed data and other information about the state of the ablation process can help ensure that the target tissue is properly ablated according to the corresponding rotor graph. This may provide a more reliable and efficacious treatment of atrial fibrillation and other cardiac arrhythmias.

As shown in the example 3D activation map of fig. 40A, there is a relatively large gap or space between adjacent electrodes of a multi-electrode device or system. As a result, corresponding 3D maps generated using only a multi-electrode mapping device or system may be inaccurate and/or incomplete. For example, in some embodiments, there may be rotors or other markers of cardiac arrhythmias (e.g., atrial fibrillation), or other conditions that cannot be identified by the fixed-space electrodes of the multi-electrode mapping device or system.

By way of example, fig. 40B shows a region 9920 of the anatomical space of a subject, which region 9920 has been mapped using a catheter-based device or system (alone or in combination with one or more other mapping devices or systems (e.g., a multi-electrode mapping system)) according to various embodiments disclosed herein. The map of fig. 40B provides additional mapping data between the disposed, fixed locations of the electrodes in a multi-electrode device or system. Such enhanced mapping systems and related methods (e.g., using the high resolution electrode embodiments disclosed herein) may be used to detect the presence of the rotor 9930 (e.g., where a region of the targeted anatomical region exhibits a local region in which activation of the tissue forms a circular or repeating pattern). Thus, using embodiments of the enhanced mapping device or system disclosed herein, the presence of a condition may be accurately identified and subsequently treated. As listed above, embodiments disclosed herein may be used to generate many types of enhanced cardiac maps, such as, but not limited to: a cardiac activation map, a cardiac activity propagation velocity map, a cardiac voltage map, and a rotor map. According to several embodiments, the enhanced mapping system facilitates a more focused, localized, or focused ablation target and/or may reduce the number of ablations required to treat various conditions.

Accordingly, the ability to generate such enhanced cardiac maps may further enhance the various graphical representations presented herein (e.g., with reference to fig. 36A-39), and may further improve ablation systems and techniques that utilize such features. For example, in some embodiments, the identification of the rotor 9930 may be superimposed or otherwise identified on a graphical representation of an ablation map of a mapping region relative to a target anatomical structure, as discussed herein, e.g., with respect to the arrangements of fig. 36A-39. As a result, a physician performing an ablation procedure can more accurately, reliably, and effectively target the appropriate portions of the subject's anatomy in an attempt to treat a condition of the subject (e.g., atrial fibrillation, other cardiac arrhythmias or diseases, other conduction-related diseases, etc.).

Hybrid contact assessment and graphical output facilitating contact assessment before/during ablation

According to several embodiments, the systems, devices, and methods described herein facilitate improved and/or enhanced catheter tip-to-tissue contact sensing, improved assessment of both before and during ablation or other treatment procedures, and the like. For example, impedance-based contact sensing techniques (such as those described herein in paragraphs [0554] - [0626 ]) can be implemented to assess the degree of catheter tip-to-tissue contact (e.g., contact level, nature of contact, magnitude of contact) prior to cardiac ablation or other therapeutic progression (e.g., prior to delivery of radio frequency energy adapted for tissue ablation or other modulation). In other implementations, contact sensing prior to initiation of ablation or energy delivery is based on local tissue voltage and/or frequency measurements obtained between pairs of electrodes positioned along the catheter tip (e.g., electrodes spaced axially along the catheter tip). During cardiac ablation or other treatment procedures, contact assessment may be achieved, facilitated, and/or improved based on various temperature measurements associated with the catheter tip. The temperature measurements may be represented graphically on the display in a manner that advantageously facilitates: (i) determine the magnitude or nature of the contact of the catheter tip to the tissue, (ii) determine the orientation of the catheter tip relative to the tissue, (iii) determine which surfaces of the catheter tip are hot (e.g., relative to a baseline temperature), and/or (iv) determine how quickly heat is emanating in order to facilitate an assessment of lesion formation.

In some embodiments, RF damage (e.g., at least partial tissue destruction) occurs when current passes through a low resistance path of the RF ablation catheter and is transmitted from the tip electrode (e.g., a compound tip electrode, such as the various compound tip electrode embodiments disclosed herein) to the return pad (pad). When the surface of the tip electrode is in contact with (e.g., at least partially in contact with) tissue, current flows from the tip electrode through the tissue to the ground pad. Since tissue has a higher electrical resistance than the RF circuit, heat is generated in the tissue. The heat is then transferred back to the tip electrode, and the surface of the tip electrode that is in direct contact with the tissue will become heated (e.g., heat transfer to the tissue will occur). In some arrangements, if RF power or energy is passed through the tip electrode while the tip electrode is in and/or surrounded by circulating blood (e.g., when there is no contact between the electrode and tissue), no or minimal heat will be generated and the surface of the tip electrode will not heat up (e.g., no or minimal heat will be transferred to the surface).

According to several embodiments, providing real-time information (e.g., a graphical display for convenience, ease of visualization, manipulation, and otherwise understanding) to a clinician to enable the clinician to assess the degree, magnitude, level, or nature of contact between a tip of a medical device (e.g., a composite tip electrode assembly disposed along a distal portion of an ablation catheter or other medical device, such as the composite tip or split-tip electrode assemblies described herein) and tissue of a subject (e.g., cardiac tissue) before and during a treatment procedure (e.g., a radio frequency ablation procedure for treating, preventing, or reducing the likelihood of atrial fibrillation results in one or more of the following advantages or benefits: (i) providing guidance to the clinician or other practitioner to make decisions (e.g., make adjustments during treatment) to prevent under-ablation or over-ablation (e.g., charring or steam "popping"), (ii) avoiding or reducing the need to rely on complex algorithms based on force, power, time, and/or other parameters; (iii) displaying or otherwise delivering local heating in real time (for treatments involving heating); (iv) extracting or otherwise providing information into a simple graphical display; (v) allowing a clinician or practitioner to readily determine the magnitude or nature of the contact and/or understand the nature of the lesion being formed (for ablation therapy); (vi) even if the underlying tissue has been ablated, it can help assess the magnitude or nature of the contact during treatment; (vii) preventing tissue perforation; and/or (viii) using the data that has been collected to determine the orientation of the catheter tip with the tissue to facilitate contact assessment.

In some embodiments, the systems and methods described herein advantageously provide a hybrid contact assessment algorithm or process that utilizes bipolar measurements (e.g., voltage, frequency, impedance measurements) obtained between two, three, or more electrode members positioned along a catheter tip (e.g., between electrode members of a composite tip electrode assembly (such as described herein) of an ablation catheter or other medical device) prior to delivery of therapeutic energy (e.g., ablation radiofrequency energy). Further, the hybrid contact assessment algorithm or process utilizes temperature measurements obtained from a plurality of temperature measurement devices (e.g., thermocouples, thermistors, other temperature sensors, etc.) positioned along the ablation catheter or other medical instrument to provide information to allow a clinician to assess the magnitude or nature of the contact while applying or delivering therapeutic energy. In some arrangements, temperature sensors (e.g., thermocouples) located along the catheter tip may continuously acquire temperature data while RF power or energy is being delivered during clinical use of the RF ablation catheter. When the catheter tip passes through the anatomy to the ablation site, the temperature sensor will read 37 ℃ or near 37 ℃ (e.g., the temperature of the blood of the subject being treated) and will not provide useful contact sensing information until the catheter tip is in contact with the tissue and RF power or energy is initiated by the RF generator. Thus, in some embodiments, prior to ablation, a non-temperature based (e.g., impedance based) contact sensing technique may be used to assess a property (e.g., overall amplitude, degree, or level) of the contact. In some embodiments, when ablation RF power or energy is initiated and applied, a temperature-based contact assessment technique may be used in place of a non-temperature-based (e.g., impedance-based) contact sensing technique.

Fig. 45 shows an embodiment of a distal portion or catheter tip 4500 of an ablation catheter. The catheter tip 4500 includes a plurality of electrode members axially spaced apart along the catheter tip 4500. The distal-most electrode members (D1, D2) may form a composite tip electrode assembly adapted for facilitating high resolution electrogram mapping at a mapping frequency (e.g., with the two electrode members acting as separate independent electrodes) and facilitating ablation RF energy delivery or transmission at an ablation frequency (e.g., with the electrode members acting as a single integral electrode), as described in more detail elsewhere herein. The distal tip electrode of the composite-tip electrode assembly is referred to as D1, and the proximal electrode of the composite-tip electrode assembly is referred to as D2. In some embodiments, third electrode D3 is spaced proximally from proximal electrode D2 of the composite-tip electrode assembly. In some embodiments, a third electrode D3 for contact sensing is positioned around the insulating sheath of the catheter shaft. Third electrode D3 may be configured to function only as an EGM recording or mapping electrode (e.g., not as an RF transmitting electrode similar to electrodes D1 and D2). The composite tip electrode assembly and ablation catheter may include and incorporate any of the structural and/or functional features (e.g., size, spacing, thermal shunting, irrigation, etc.) of any of the embodiments described herein. For example, the catheter tip 4500 may include a plurality of distal temperature sensors 4525A and a plurality of proximal temperature sensors 4525B, such as disclosed in fig. 18A-19D. The catheter tip 4500 may also include an electrical insulation gap 4531 between a proximal edge of the distal tip electrode D1 of the composite tip electrode assembly and a distal edge of the proximal electrode D2 of the composite tip electrode assembly, and one or more thermal shunt members 4545, such as disclosed in, for example, fig. 9-17B, 18C, 19C, 20. As shown, the ablation catheter tip 4500 may also further include additional mapping electrodes (R1, R2) positioned proximal to the third electrode D3 and along the insulating sheath of the ablation catheter shaft. According to several embodiments, the illustrated ablation catheter tip 4500 does not include microelectrodes.

Turning to fig. 42A, in some embodiments, hybrid contact assessment method 4200A includes generating (at block 4205A) an output indicative of catheter tip-to-tissue contact based on local measurements (e.g., bipolar tissue voltage, tissue impedance, and/or tissue frequency measurements) obtained between two or more electrode members positioned along a catheter tip for display. Referring to fig. 45, bipolar electrical measurements (e.g., voltage, current) may be obtained between respective pairs of three electrode members (e.g., between D1 and D2, between D1 and D3, and/or between D2 and D3). In several embodiments, it is advantageous to obtain measurements without the need for external signals (e.g., applying signals from a signal generator or other signal source) to facilitate contact assessment. Rather, according to such an arrangement, the measurement depends on the inherent electrical properties or signals present in the target body tissue (e.g., cardiac tissue).

The pumping action of the heart is regulated by an electrical conduction system that coordinates the contraction of the various chambers of the heart. Uniquely, the myocardium has the ability to initiate potentials at a fixed frequency that rapidly diffuse between cells to trigger contractile mechanisms. This potential is a transient change in voltage across the cell membrane of the heart cell. The intrinsic voltage of the heart tissue can be measured differently, conventionally in the form of an ECG, an EGM, an EKG, etc. In some embodiments, the voltage measurement is not determined from electrographic recording (EGM) and is not a measurement between the electrode and the tissue (e.g., electrical coupling). Rather, in some embodiments, the voltage measurement is a bipolar measurement between two electrodes axially spaced apart on the catheter tip.

In some embodiments, the nature and intensity of the measured intracardiac voltage is directly related to the electrode configuration used for the measurement. According to several embodiments, the electrode configuration of the catheter tip 4500 is configured to measure local cardiac tissue voltages. For example, the size of the electrodes D1, D2, D3 and the separation distance between the electrodes may advantageously allow the electrodes to accurately sense the near-field voltage generated from tissue in direct contact with the electrodes D1, D2, D3 of the catheter tip (and the measurement is not affected or influenced by the far-field voltage). As a result, the local tissue voltage measured between the electrodes may provide a reliable way of assessing tissue contact. For example, the use of three electrodes axially spaced along the length of the catheter tip advantageously facilitates reliable assessment of the orientation and excessive penetration of the catheter tip. The relatively small surface area and close spacing (e.g., small separation distance) between the electrodes may facilitate localization of the measurements, as more near-field (and less noise) is measured. Conventional mapping catheters with large tip electrodes of large surface area measure far field, and voltage measurements are typically averaged over the large surface area, so the measurements are not localized. In some embodiments, the spacing between each of the electrodes D1, D2, D3 is in the range of about 0.10mm to about 2.0mm (e.g., 0.10mm to 0.50mm, 0.30mm to 0.80mm, 0.50mm to 1.5mm, 0.60mm to 1.8mm, 1.0mm to 2.0mm, overlapping ranges thereof, or any value within the recited ranges). The spacing or separation distance between electrodes D1 and D2 and between D2 and D3 may be the same or may be different. The length of electrodes D1, D3 can be about 0.25mm to about 2.5mm (e.g., 0.25mm to 1.5mm, 0.50mm to 2.0mm, 0.25mm to 1.0mm, 0.50 to 1.5mm, 1.0mm to 2.5mm, 1.0mm to 2.0mm, overlapping ranges thereof, or any value within the recited ranges) in addition to the length of the electrodes or electrode portions (e.g., electrodes 30A, 30B) described elsewhere herein. In some embodiments, the length of electrode D2 is in a range from about 1.0mm to about 5.0mm (e.g., from 2.0mm to 5.0mm, from 1.0mm to 4.0mm, from 1.5mm to 3.5mm, from 2.0mm to 4.0mm, from 2.5mm to 5.0mm, from 3.0mm to 5.0mm, from 2.5mm to 4.5mm, overlapping ranges thereof, or any value within the recited ranges).

Various instruments (e.g., a spectrum analyzer or oscilloscope) can be used to measure cardiac voltage. Since the heart frequency may be below 10Hz, the measuring instrument is advantageously able to handle a range of at least 1-10 Hz. Relatively small cardiac voltages (typically ranging between 0.1mV to 5 mV) can be amplified (as needed) using hardware (e.g., one or more amplifiers) and/or software (e.g., one or more signal multipliers) before or after the measurement. Various connections and devices to the catheter introduce noise as the cardiac voltage travels (e.g., from the electrodes) to the point of measurement. Thus, in some arrangements, a low pass filter (e.g., having a cutoff frequency of 50Hz or lower) may be used to remove these noises.

According to several embodiments, one or more amplifiers are advantageously positioned to follow one or more filters (e.g., notch filter (s)) in energy delivery module 40 (e.g., RF generator) that remove (e.g., filter out) the ablation frequency (e.g., 450kHz) from the contact sense signals obtained from contact sense electrodes D1, D2, D3. In other words, the contact sensing measurements are obtained from the output of one or more filters in the energy delivery module 40 (e.g., RF generator) and isolated from noise effects that would be introduced if the contact sensing measurements were obtained at a point adjacent to the electrophysiology mapping display and/or recording system. In some embodiments, the contact sensing signal (from which the contact sensing measurements are taken) travels directly from the catheter along one or more cables to a generator, and then through one or more filters as described above, and then to one or more amplifiers. One advantage of such positioning of one or more amplifiers is that: a display indicating lesion formation (e.g., dynamic scale 4613 or a lesion complete indicator described below) will be more accurate because less noise is introduced into the touch sense signal. If the signal is too noisy (e.g., because the signal travels through a proprietary RF generator and/or non-proprietary electrophysiology hardware components connected to the RF generator), it may affect the clinician's ability to see when the signal is completely attenuated and when the clinician should stop delivering ablation energy (as described in more detail below). The positioning of the amplifier as described herein may better ensure the quality and accuracy of ablation monitoring.

According to several embodiments (such as, for example and without limitation, when a spectrum analyzer is used to measure voltage), the measured time domain signal is converted to the frequency domain and displayed on a display screen to find the frequency at the peak. In some embodiments, the voltage signal is converted to the frequency domain using a frequency transform, such as fourier, Fast Fourier Transform (FFT), wavelet, Wigner-Ville. Various instrument software modules or programs (such as LabVIEW provided by National Instruments) may be used for signal acquisition, noise filtering, FFT, peak voltage measurement, and frequency detection at peak.

According to several embodiments, the nature (e.g., amplitude, orientation) of the catheter tip-to-tissue contact may be determined from direct measurements or from a comparison of measurements between contacting sensing electrodes (e.g., electrodes D1, D2, D3). The magnitude or level of the contact may be based on both the voltage amplitude and the pulse width. The amplitude of the recording voltage between the two electrodes times the duration of the pulse is equal to the amplitude of the contact. The pulse width will continue to increase when the voltage amplitude reaches a peak or reaches saturation after the optical contact has at least been achieved. Thus, an increased contact level may be indicated or determined based on an increase in pulse width, even if the amplitude is not increased or not significantly increased. In some embodiments, if the measured pulse has a significantly high amplitude (e.g., 1.5mV to 4.0mV) and a wide pulse width (e.g., 10-20 ms), the tip is determined to be in strong contact with the tissue. If the measured pulse has a relatively high amplitude (e.g., 0.1 to 1.0mV) but a very narrow pulse width (e.g., 2-9 milliseconds), the tip is determined to be in light contact with the tissue. According to several embodiments, the pulse width is measured at a signal amplitude (e.g., voltage amplitude) of between 40% and 70% of the maximum amplitude (e.g., between 40% and 60%, between 50% and 70%, any value within the recited range, 50%). Measuring with signal amplitudes in this range may advantageously ensure that the width of the actual biosignal is measured without including noise elements in the measurement that would affect the integrity of the measurement. In some embodiments, the contact level may be based on envelope detection (e.g., pulse width), rather than just on peak-to-peak amplitude.

In some embodiments, the properties of the catheter tip may be determined (e.g., upon execution of software instructions stored on a non-transitory computer-readable medium by a processor) according to the following parameters or conditions (e.g., based at least in part on the amplitude and/or pulse width of the voltage measurements between the contacting sensing electrodes):

1. in some embodiments, if the voltage measurements between electrodes D1 and D2 and between electrodes D2 and D3 are substantially equal (e.g., within a certain threshold percentage of each other, such as between about 80% to about 100% of each other), the orientation of the catheter tip relative to the target tissue is determined to be substantially parallel; .

2. In some embodiments, the orientation of the catheter tip relative to the target tissue is determined to be generally perpendicular if the voltage measurement between electrodes D1 and D2 is not substantially equal to the voltage measurement between electrodes D2 and D3;

3. in some embodiments, as the magnitude of the voltage measurement between electrodes D1 and D3 increases, the magnitude of the catheter tip-to-tissue contact increases;

4. in some embodiments, if the magnitude of the voltage measurement between electrodes D1 and D2 stops increasing (while the frequency stops decreasing) and the magnitude of the voltage measurement between electrodes D2 and D3 begins and continues to increase (while the frequency continues to decrease), the vertical tip contact is increasing and there may be a risk of perforation. In this case, a visual, audible, or tactile alarm may be generated and output.

According to several embodiments, the level or degree of contact is determined based on a relative relationship between voltage and/or frequency measurements rather than on an absolute quantity, value or measurement. The level or degree of contact may also be determined (e.g., using a relative relationship) based on the tissue type, the nature of the tissue, or any other tissue characteristic. For example, diseased or ablated tissue may begin at a lower initial voltage amplitude value than healthy, living tissue, and the voltage amplitude may not increase as much as a higher contact level is reached when in contact with diseased or ablated tissue; however, the pulse width may still increase and may provide an indication of an increased level of contact.

In some embodiments, voltage measurements are made between respective contacting sensing electrodes along the catheter tip and separate reference electrodes (e.g., in a monopolar fashion) instead of or in addition to bipolar voltage measurements. The monopolar voltage measurement may also be used to indicate the nature of the tip in contact with the tissue according to parameters or conditions similar to those described for the bipolar voltage measurement.

Instead of or in addition to voltage measurement, voltage measurement configurations or parameters (e.g., algorithms, conditions) may also be used for frequency measurement or impedance measurement. The voltage measurement is in the time domain. The time domain may be converted directly to the frequency domain (e.g., using fourier, laplace, and/or Z transform techniques). According to several embodiments, it may be advantageous to evaluate both voltage measurements and frequency measurements. According to several embodiments, the frequency advantageously provides a higher degree of consistency, specificity and sensitivity for the measurements (particularly when distinguishing between contact and non-contact and between living, diseased and ablated tissue). The three tissue types (live, diseased, ablated) each have different frequency spectra. Thus, as the peak frequency (the frequency at the peak) changes, the frequency response of the tissue during the ablation process may be able to show the progression from live tissue to ablated tissue. In addition, since blood has neither a voltage nor a frequency, and diseased or ablated tissue has a low voltage and corresponding frequency, in certain cases where the voltage or frequency alone does not provide discrimination of tissue type and contact information, the use of both voltage and frequency may provide discrimination of tissue type and contact information.

After initiating delivery of ablation power or energy, and while ablation power or energy is being delivered, method 4200A switches (at block 4210A) to generate for display an output indicative of contact based on temperature measurements (e.g., temperature measurements determined from a plurality of temperature measurement devices, such as temperature sensors 4525 positioned along the distal portion 4500 of the ablation catheter or other medical instrument).

Referring to fig. 42B, hybrid contact assessment method 4200B includes generating (at block 4205B) for display an output indicative of tip-to-tissue contact based on impedance values or measurements (e.g., bipolar impedance measurements taken between two electrode members of a composite tip electrode assembly or between any two electrodes of a medical device) prior to delivery of ablation energy. Contact assessment based on impedance values or measurements may be performed using any of the systems, apparatus, and methods described herein (e.g., the contact sensing subsystems described herein and systems, apparatus, and methods such as those described in paragraphs [0554] - [0626 ]). After initiating delivery of the ablation power or energy, and while the ablation power or energy is being delivered, the method 4,200B switches (at block 4,210B) to generate for display an output indicative of the contact based on temperature measurements (e.g., temperature measurements determined from a plurality of temperature measurement devices, such as temperature sensors positioned along a distal portion of an ablation catheter or other medical instrument).

In embodiments involving an ablation catheter or other medical device having a composite tip electrode assembly adapted for providing contact assessment based on bipolar impedance measurements between two electrode members at a contact sensing frequency and delivering ablation radiofrequency power or energy as a single tip electrode (such as many of the configurations described herein or equivalents thereof), contact assessment based on bipolar impedance measurements may not be physically performed while ablation energy is being delivered. Thus, contact assessment based on temperature measurements may be advantageously used to provide continuous real-time assessment of contact as ablation power or energy is applied to the tissue.

In some embodiments, the method 4200 includes determining (at block 4208) whether ablation power or energy is being applied to tissue. The determining may include determining a current operating mode of an energy delivery module (e.g., an RF generator). For example, if the RF generator is determined to be in a pre-ablation mode (e.g., based on a data flow menu of the generator), the contact assessment may be based on the impedance measurement, and if the RF generator is determined to be in an ablation mode, the contact assessment may be switched to be based on the temperature measurement. In some embodiments, all or a subset of the steps of hybrid contact evaluation method 4200 may be performed by a single hybrid contact evaluation subsystem or module or any of the contact sensing subsystems or modules described herein. In some embodiments, the various steps are performed by separate contact sensing subsystems or modules, as desired or required. For example, contact assessment based on impedance values or measurements may be performed by a first subsystem or module (e.g., performed based on stored instructions in a tangible computer-readable medium of the first subsystem or module), and contact assessment or output generation based on temperature measurements may be performed by a second subsystem or module (e.g., performed based on stored instructions in a tangible computer-readable medium of the second subsystem or module). The methods 4200A, 4200B and/or the contact assessment subsystem or module implementing the methods 4200A, 4200B may be executed by one or more processing devices (e.g., the processor 46 of fig. 1) and/or stored in memory of the one or more processing devices. The module may be stored in memory and may include algorithms or machine-readable instructions to be executed by one or more processing devices.

As described, for example in connection with fig. 18A-23F-3, an ablation catheter may include a composite tip electrode assembly having a distal tip electrode member and a proximal electrode member spaced a gap distance from the distal tip electrode member, wherein the two electrode members are coupled to one another by a filtering element (e.g., a capacitor). In some embodiments, as discussed in more detail herein, when power having a frequency within the ablation frequency range is applied, the two electrode members function like a single tip electrode due to the electrical properties or characteristics of the filtering element. When signals having frequencies in the high-resolution mapping frequency range are applied, the two electrode members act as separate electrodes due to the electrical properties or characteristics of the filtering elements. As also described above in connection with fig. 18A-23F-3, the ablation catheter may include a plurality of temperature measurement devices positioned along the length of the distal portion of the ablation catheter. The temperature measurement device may advantageously be positioned at or near an area of the electrode member where RF induced hot spots may occur in order to capture the hottest temperatures. For example, the ablation catheter may include a first plurality of temperature sensors positioned along a distal face of the distal tip electrode member and a second plurality of temperature sensors positioned along or adjacent to the proximal electrode member (e.g., within 1mm or about 1mm of the proximal or distal side of the proximal electrode member).

In some embodiments, the first plurality of temperature-measurement devices consists of three temperature sensors positioned equally or substantially equally spaced from each other on the distal side of the distal tip electrode member (e.g., 120 degrees or about 120 degrees apart relative to the central longitudinal axis of the catheter tip), and the second plurality of temperature-measurement devices consists of three temperature sensors positioned equally or substantially equally spaced from each other at or adjacent to the proximal end (e.g., edge) of the proximal electrode member (e.g., 120 degrees or about 120 degrees apart relative to the central longitudinal axis of the catheter tip), or near the proximal end of the proximal electrode member. Each of the first plurality of temperature measurement devices may be horizontally aligned (e.g., in a first plane perpendicular or substantially perpendicular to a longitudinal axis of the catheter tip) or substantially aligned, and/or each of the second plurality of temperature measurements may be horizontally aligned (e.g., in a second plane intersecting the longitudinal axis of the catheter tip) or substantially aligned. In some embodiments, each of the first plurality of temperature measurement devices is vertically aligned or substantially aligned with a respective one of the second plurality of temperature measurement devices.

According to several embodiments, the use of three proximal temperature sensors and three distal temperature sensors advantageously provides an effective amount of surface coverage while reducing cost, complexity, and/or number of parts, thereby providing accurate (or substantially accurate) orientation determination and facilitating contact assessment with sufficiently high confidence. In some embodiments, three proximal temperature sensors and three distal temperature sensors arranged and positioned in the manner described in accordance with the configurations disclosed herein may be advantageously used to thermally map the entire surface of an electrode during ablation to provide a meaningful contact indicator and/or lesion assessment indicator, as the magnitude of the sensed temperature is directly related to the magnitude or degree of contact of the respective sensor with tissue. However, in other embodiments, more or less than 3 proximal temperature sensors and/or more or less than 3 distal temperature sensors (e.g., two, four, five, six temperature sensors or more than six temperature sensors) may be used in the system, as desired or required.

As described, for example, in connection with fig. 23F-1 through 23F-3, a graphical output indicative of the orientation of the catheter tip may be generated for display on a graphical user interface. The graphical output may be generated and displayed prior to and/or during ablation. In some embodiments, a graphical output may be generated for display on a graphical user interface to facilitate contact assessment based on temperature measurements determined (e.g., calculated) from a temperature measurement device (e.g., three proximal temperature sensors and three distal temperature sensors). For example, as shown in fig. 43A and 43B, a graphical representation 4305 (e.g., a two-dimensional or three-dimensional image) of the catheter tip may be displayed. The graphical representation 4305 of the tip may be subdivided into separate discrete zones or regions corresponding to or associated with each of the temperature measurement devices (e.g., thermocouples). For example, for an ablation catheter having three proximal temperature sensors and three distal temperature sensors (e.g., thermocouples) as described herein, the graphical representation 4305 of the tip may be subdivided into six zones (three distal-D1, D2, D3 and three proximal-P1, P2, P3) and the zones may be further subdivided by 120 degrees (as shown in fig. 43A and 43B). Each of the zones may provide a graphical output indicative of a real-time temperature reading of one of the temperature sensors and thus indicative of the temperature of tissue in contact with the zone of the catheter tip. For example, instead of displaying a graph (such as the graphs shown in fig. 23A and 23B) of the temperature readings of each of the temperature sensors over time, the graphical output may provide a more simplified visual icon and/or other graphics so that the clinician may easily and intuitively determine the nature of the contact between the catheter tip and the tissue at various regions along the catheter tip.

The graphical representation 4305 of the tip may include multiple graphical representations of various views (e.g., side views, cross-sectional views) of the catheter tip so that all of the zones may be seen at any particular time. As shown in fig. 43A and 43B, in addition to the graphical representation 4305 of the tip, the graphical output may also include separate graphical outputs (e.g., icons, other images, etc.) showing independent zones corresponding to each of the proximal temperature sensors (e.g., icon 4307) and showing separate independent zones corresponding to each of the distal temperature sensors (e.g., icon 4308), as all of the zones may not be visible in the graphical representation 4305 of the catheter tip at any time.

The graphical output advantageously displays the local heating that is occurring in real time. The graphical output may advantageously facilitate real-time, intuitive, easy-to-understand assessment of contact and/or lesion formation by the clinician. For example, each of the zones may be color coded based on the current temperature reading. As one example, the zones may change in color (chromatically) from a light color to a dark color (e.g., from yellow to red) as a function of temperature changes in each respective zone, where the light color (e.g., lighter hue or shade) corresponds to a minimum temperature (e.g., 36 or 37 degrees celsius indicating no tissue contact and only blood contact) and where the dark color (e.g., darker hue or shade) corresponds to a maximum temperature (e.g., a set point or peak temperature of 60 degrees celsius or higher). As another example, the color may change along a continuous spectrum of colors (e.g., colors of the visible spectrum), changing from violet to blue to green to yellow to orange to red with increasing temperature. According to several embodiments, each degree of temperature may be associated with a particular set of values using an RGB or HSL color model. The color change may vary from light to dark (e.g., changing shade, hue, and/or brightness) for a first color, light to dark for a second color, and light to dark for a third color. Any number of colors (e.g., two, three, four, five, six, seven, or more) and any particular color may be used.

In some embodiments, for each color (e.g., changing shading), the color does not change substantially continuously from light to dark as the temperature value increases. Instead, a single bright color (e.g., yellow) is used for the first range of lowest temperature values, a single darker color (e.g., orange) is used for the second range of medium temperature values, and a single darkest color (e.g., red) is used for the third range of highest temperature values. Again, any number of colors (e.g., two, three, four, or more than four) or any particular color may be used as desired. A clinician or other user may be able to select or adjust colors, the number of colors, and/or whether the colors change in color (e.g., different shades or hues) for each color.

In some embodiments, digital information (e.g., actual temperature values) may also be displayed for each zone (e.g., continuously or only when the temperature values are above a threshold). In any of the described embodiments, a temperature legend or scale 4410 may be output on the display to correlate temperature values to particular colors. The maximum and minimum temperatures on the legend or scale may optionally be adjusted (e.g., increased or decreased) by the clinician (e.g., via up and down arrows, by typing numbers in text fields, or other user input on a graphical user interface).

According to several embodiments, the color may indicate various levels, degrees, or magnitudes of contact of the region (e.g., zone location) of the catheter tip with the tissue. In some embodiments, a separate indicator (e.g., textual or graphical) is displayed and configured to indicate when the temperature value for any of the zones or regions correlates to when a sufficient level of contact (e.g., a threshold contact temperature) has been achieved by one or more of the regions. In some embodiments, a slider, a scale, a gauge indicator, and/or any other indicator may be displayed to indicate the level, degree, or magnitude of contact.

In some arrangements, the graphical representation 4305 of the tip is adapted for rotation in real-time (e.g., substantially continuously or at periodic time intervals) based on the orientation determination calculation. For example, fig. 43A shows one embodiment of a graphical output when the catheter tip has a vertical orientation, and fig. 43B shows one embodiment of a graphical output displayed at times when the catheter tip has a parallel orientation.

Referring to fig. 44A-44C, the graphical representation 4405 of the catheter tip may be represented as a single unitary electrode, and pixelation may be used to indicate the current temperature over the entire catheter tip in a continuous manner (e.g., rather than discrete and separate regions of the representation as shown in fig. 43A and 43B). This provisional application also provides color versions of the graphical outputs of fig. 44A-44C. The black and white versions of fig. 44A-44C include a pattern of shading to distinguish colors. Fig. 44A shows an example of a screenshot of the graphical output at a time when it is determined that the catheter tip is in a tilted orientation. As shown in fig. 44A, the graphical representation 4405 of the catheter tip indicates that the temperature is highest at the region of the catheter tip in contact with the tissue and transitions to a cooler temperature at a point further away from the tissue contact. In the depicted arrangement, in the tilted orientation, the highest temperature is isolated to a relatively small area of the catheter tip. Fig. 44B shows an example of a screenshot of the graphical output at a time when the catheter tips are determined to be in a parallel orientation. As shown in fig. 44B, the graphical representation 4405 of the catheter tip indicates that the temperature is high along the entire length of the surface in contact with the tissue, and that the temperature gradually decreases with distance from the contact surface. As seen in fig. 44B, in the parallel orientation, there is relatively no "cold" spot at that particular moment. Fig. 44C shows an example of a screenshot of the graphical output at a time when the catheter tip is determined to be in a vertical orientation. As shown in fig. 44C, the graphical representation 4405 of the catheter tip indicates that the temperature is highest at the distal tip of the catheter tip (which is in direct contact with the tissue) and gradually transitions to a cooler temperature as the distance from the distal tip increases. In some embodiments, a 256 color scheme may be used in which the colors are discretized and range from dark blue for the coldest temperatures to dark red for the hottest temperatures, such that as the temperature increases, the colors generally transition from blue to green to yellow to orange to red. Any other color scheme (e.g., a color scheme with a resolution greater or less than 256 colors) may be used as desired or required.

One or more interpolation algorithms may be used to interpolate the temperature at locations between the temperature sensors (e.g., spaced from the direct region or regions surrounding any one of the temperature sensors so as to provide a continuous temperature indication along the catheter tip rather than only in the region immediately surrounding the temperature sensor). For example, if the temperature at each of the temperature sensor locations is known, the temperature at the locations between the temperature sensors may be calculated or determined (e.g., interpolated) based on the known temperature values at the temperature sensor locations. In some embodiments, a bilinear interpolation algorithm or method is used to determine the temperature of the rectilinear two-dimensional grid between the temperature sensors. The interpolated temperature values may be mapped to or correlated with a color (e.g., one of 256 discrete colors from blue to red). The resolution of the temperature may advantageously be chosen to reduce computational power and time. Various sizes may be used for the two-dimensional interpolation grid depending on the desired resolution (e.g., 10x 10, 5x 5, 20x 20, 50x 50, 100x 100, 2x 2, 5x 10, 20x 40, 50x 100, etc.). Other two-dimensional or three-dimensional interpolation algorithms or methods may be used in other embodiments (e.g., bicubic interpolation, trilinear interpolation, tricubic interpolation, nearest neighbor interpolation, natural neighbor interpolation, spline interpolation, radial basis functions, inverse distance weighting, etc.). If one-dimensional is not used, a three-dimensional interpolation algorithm or method may be used for two-dimensional interpolation.

Methods of determining orientation based on temperature measurements obtained from temperature sensors are described above (e.g., in conjunction with fig. 23C-23E). In one embodiment of the orientation determination operation (e.g., at block 23040 of process 23000), the processing device, when executing the stored instructions, first evaluates criteria for a vertical orientation in a steady-state stage. For example, the vertical orientation criterion may be satisfied if the sum of the temperature measurements of the distal temperature sensors is at least 15% greater than the sum of the temperature measurements of the proximal temperature sensors and the temperature measurements of the distal temperature sensors are the same or very close to each other (e.g., within 5 degrees celsius of each other). In some embodiments, if the vertical orientation criterion is not satisfied, the orientation determination operation is then performed to evaluate the criterion for parallel orientation. For example, if the maximum temperature measurement of the proximal temperature sensor and the maximum temperature measurement of the distal temperature sensor are the same or very close to each other (e.g., within 5 degrees celsius of each other), the parallel orientation criterion can be satisfied. If the vertical and parallel orientation criteria are not satisfied, an embodiment of the orientation determination operation determines that the catheter tip is in a tilt determination (e.g., halfway between parallel and vertical, or at a 45 degree angle) if the maximum temperature measurement of the proximal temperature sensor and the maximum temperature measurement of the distal temperature sensor differ by more than a threshold percentage (e.g., 30-40%, or any integer value within the range). If the maximum temperature value of the distal temperature sensor is higher than the maximum temperature value of the proximal temperature sensor, the processing device determines that the catheter tip is oriented downward, as shown in FIG. 44A. If the maximum temperature value of the proximal temperature sensor is higher than the maximum temperature value of the distal temperature sensor, the processing device determines that the catheter tip is oriented upward, as shown in FIG. 44D. As with fig. 44A-44C, this provisional application provides a color version of the graphical output of fig. 44D.

In some embodiments, the orientation is selected from one of three discrete orientations (parallel, perpendicular, or 45 degree tilt) based on various comparisons of temperature values of the temperature sensors (as described in more detail above). In some embodiments, interpolation algorithms and/or techniques may be used in order to output the orientation for display between the three discrete orientations, making the orientation graphic output more accurate, and also facilitating a smooth, continuous transition between the three discrete orientations. For example, any orientation angle between vertical and tilt can be calculated by linear interpolation between vertical and 45 degree tilt orientations. Any orientation angle between parallel and tilt can be calculated by linearly interpolating the parallel and 45 degree tilt conditions. The calculated orientation angle may be used to cause the display of the catheter tip to have the currently calculated orientation angle, rather than displaying the catheter tip at only one of three discrete angles corresponding to parallel, perpendicular, and 45 degree tilt.

According to some embodiments, current color and color changes may advantageously alert the clinician in real-time as to: the speed at which a lesion is formed at a particular ablation site (e.g., the rate at which the catheter tip "heats up"), the degree or nature of contact with the tissue (by looking at which zones or regions are hot, and which zones or regions are not hot and how hot the zones or regions are), and/or the orientation of the tissue with respect to the catheter tip. The clinician can monitor the graphical output and make decisions to adjust the position of the catheter tip or parameters of the treatment in real time because the catheter tip is not necessarily stationary during the course of the treatment (e.g., the catheter tip may move due to cardiac cycles, blood flow, patient movement, movement due to respiration, etc.). For example, if a region or zone is heated rapidly (or typically the catheter tip is heated), the lesion may be formed relatively quickly and the clinician may decide to ablate for a shorter time. In some embodiments, rapid heating means that the setpoint temperature is reached within a particular amount of time after initiating energy delivery (e.g., within 5 seconds or less, within 10 seconds or less, within 20% of the total ablation therapy duration, within 25% of the total ablation therapy duration, within 15% of the total ablation therapy duration, within 10% of the total ablation therapy duration, within 30% of the total ablation therapy duration). Conversely, if the zone or region heats up relatively slowly (or typically the catheter tip heats up) or not at all, the clinician may decide to reposition the catheter or ablate for a longer period of time. If all of the area or regions of the catheter tip are uniformly heated, the clinician can determine that the tip is completely or substantially completely buried in tissue (e.g., a pocket or tissue completely wrapped around the catheter tip). If only the distal region or area is heated (or rapidly heated relative to other regions or areas), the clinician can be more confident that the catheter tip is perpendicular (or substantially perpendicular) to the tissue. If the combination of the proximal and distal regions or areas become hot, the clinician may be more confident that the catheter tip is parallel or substantially parallel to the tissue. The graphical output may advantageously assist the clinician in understanding the nature of the lesion being formed and thus the clinician may adjust based on the graphical output or information to avoid over ablation, under ablation, charring, steam pop, tissue penetration, or other deleterious effects.

In some embodiments, the graphical output may provide advantages over force and/or impedance based contact assessment. For example, a catheter tip located in a tissue pocket will have significantly different injury properties than a catheter tip that slides along smooth muscle tissue, even if the same amount of force is applied to the catheter tip. The ability to determine that the catheter tip is in the pocket based on the graphical output of the temperature measurement can avoid charring, steam pops, or other deleterious effects. As another example, contact sensing based solely on impedance measurements may not provide accurate information for tissue that has been ablated because the impedance value varies based on tissue characteristics, while temperature measurements are not affected by tissue impedance changes. Thus, in some embodiments, data/information obtained or derived based on temperature measurements is clinically superior to impedance-only based contact sensing for the case where ablation is performed on previously ablated tissue (e.g., during a pulmonary vein isolation procedure). According to several embodiments, the graphical output provided herein is simpler and does not rely on calculations using complex algorithms based on multiple factors (e.g., force, power, and time).

The graphical output may optionally include a display of the temperature measurements of each of the temperature sensors over time (e.g., as shown in fig. 23A and 23B), which may also provide both a graphical indication of orientation and qualitative and quantitative information related to the real-time temperature measurements. The color code or color may be replaced (and/or supplemented) with other graphical schemes, indicators or representations (e.g., hatch patterns or shades of gray, alphanumeric characters, colors other than yellow and red, etc.). A visual, tactile, and/or audible alert may also be generated when a set point temperature (e.g., a peak temperature) is reached and/or when a temperature reaches a threshold temperature that is below the set point temperature.

The biophysics of radiofrequency tissue ablation are governed by the temperature of the tissue. For example, in the case where the tissue temperature is greater than a certain threshold temperature (e.g., 50 ℃), it may be assumed that the cells of the tissue are destroyed. The destroyed cells then become electrically inactive. According to several embodiments, selective rendering of a target region of the heart electrically inert with RF energy is effective in treating cardiac arrhythmias. Knowing the volume size of the RF lesion formed during the ablation process can be a very important clinical endpoint. According to several embodiments, lesion size and the rate of lesion formation may be determined, at least in part, by how many catheter tips are indicated to have a temperature sufficient to destroy or ablate tissue. A small portion of the catheter tip may mean a small and slowly formed lesion, while a large portion of the catheter tip may mean a larger and more quickly formed lesion. According to several embodiments, the resulting lesion volume is evaluated without using a fixed power and time algorithm.

In some embodiments, according to several embodiments, a temperature-based algorithm may be used to predict lesion volume and/or wall penetration of the lesion through tissue. In one embodiment, a temperature-based algorithm is used as follows:

(set temperature) x (time) x (% tip in contact with tissue)% damage volume index

Wherein:

set point temperature (c) — the temperature set on the energy delivery module (e.g., RF generator) or the tip-to-tissue interface temperature;

time (seconds) the duration of current rf power or energy application (e.g., duration of ablation);

contact% (mm)²) Percent of surface area of the catheter tip (e.g., composite tip electrode) in contact with tissue, as defined as the percentage of the electrode at a temperature equal to or greater than a threshold percentage (e.g., 90%) of the set point temperature; and

the surface area of the catheter tip (tip electrode) can be calculated using the formula for the surface area of the cylinder: pi r²+2 pi rh, where r is the radius and h is the height of the cylinder.

The above lesion volume prediction algorithm or other temperature-based algorithms are used or performed in conjunction with orientation determination and temperature-based contact assessment methods, techniques, and algorithms also described elsewhere herein, according to several embodiments. In some embodiments, the processing device (e.g., processor 46) begins calculating the lesion volume prediction algorithm when the RF energy is turned on, or when the generator initiates the application of RF energy or energy. In some embodiments, the region 4412 outlined in dashed lines in fig. 44B and 44C represents an example of a region of the surface area of the electrode at a temperature equal to or greater than a threshold percentage (e.g., 90%) of the target, set, or peak temperature.

The calculated lesion volume index may be generated according to a lesion volume prediction algorithm, in some embodiments, displayed in real-time on a graphical user interface, for example, as schematically shown in fig. 44B and 44C, a numerical display of the output index 4414 to be displayed alongside a graphical image of the catheter tip, the lesion volume index may advantageously inform the clinician of the nature (e.g., size and/or rate of formation) of the lesion, the clinician may direct his progress of ablation based at least in part on the magnitude of the calculated index, for example, the clinician may adjust the orientation or amount of pressure or force based on the index, or may manually terminate ablation when the index reaches a given value (e.g., a predetermined value or threshold), in some embodiments, the energy delivery module or other component of the treatment system automatically terminates ablation when the given value is reached, in some embodiments, an alert is generated when the given value is reached (e.g., a visual alert is output on a display, an audible sound is generated, and/or a vibration or other alert is output to a handle of the ablation catheter, for example, a visual alert is generated when the index is less than a given value (e.g., a visual alert, a) is output, a thin tissue volume index, a given value, such as a less than a study, a thin tissue, or thicker tissue than a given value, such as a study tissue, a study, tissue with a study, such as a study, tissue with a study.

In some embodiments, the graphical output includes a graphical representation of the tissue plane 4315 to facilitate a visual picture of the orientation of the catheter tip relative to the tissue (e.g., such that the graphical representation of the catheter tip 4305 is overlaid on the graphical representation of the tissue 4315). The graphical output may optionally include a visual representation or graphic 4320 that shows the nature of the lesion that is likely to form under the tissue based on the current orientation determination and temperature measurement, for example as shown in fig. 43A and 43B.

Fig. 46A and 46B illustrate an embodiment of graphical output before (fig. 46A) and during (fig. 46B) delivery of ablation energy (e.g., ablation RF energy) when the orientation of the catheter tip to the tissue is determined to be perpendicular, and fig. 47A and 47B illustrate an embodiment of graphical output before (fig. 47A) and during (fig. 47B) delivery of ablation energy (e.g., ablation RF energy) when the orientation of the catheter tip to the tissue is determined to be parallel (e.g., by the contact sensing module or subsystem when the one or more processors execute the stored instructions). As shown, the graphical output may include a visual image or representation (e.g., graphical tip icon) 4405 of the catheter tip and one or more dynamic scales, bar charts, or gauges 4613 located adjacent to the visual image or representation 4405 of the catheter tip. The dynamic scale 4613 may be located at any position (e.g., on one side of the graphical tip icon, on an opposite side of the graphical tip icon, above or below the graphical tip icon). The one or more dynamic scales 4613 may include, for example, a voltage scale 4613A and/or a frequency scale 4613B that displays (e.g., continuously, intermittently, etc.) to an operator the maximum real-time voltage and/or frequency amplitude between respective pairs of electrodes of a sensing electrode (e.g., electrodes D1, D2, D3 of ablation catheter tip 4500). In some embodiments, voltage scale 4613A shows a composite of the maximum amplitude and the maximum pulse width (e.g., based on a ratio of the two measurements). In several implementations, a significant increase in the amplitude observable on one or both of the scales 4613 from the initial steady-state level is indicative of initial tip contact with tissue. The amplitude may then gradually increase as increased contact between the catheter tip and the tissue is achieved.

The dynamic scale 4613 and graphical tip icon display 4405 are configured to be dynamically updated in real-time. "real-time" is used herein as understood in the art, and may mean "sufficiently immediate" or "without involving a significant time lag as perceived by an operator or viewer. Referring to the displays in fig. 46A and 47A, "the color of the graphical tip icon 4405 can be programmed to change as the corresponding measurement value between the contact sensing electrodes changes to indicate the nature of the tip in contact with the tissue and the orientation in which the electrodes are contacting the tissue. For example, in blood (no contact), the entire graphical tip icon 4405 may be displayed in a single solid color, but when the catheter tip is in contact with tissue, a second color may be used to indicate which surfaces of the tip electrode are contacting the tissue. In some embodiments, prior to delivering ablation energy, the portion of the representative catheter tip of the graphical tip icon 4405 representing the surface area of the catheter tip determined to be in contact with tissue may be displayed in a different color than the color of the portion of the representative catheter tip of the graphical tip icon 4405 representing the surface area determined to be in contact with tissue based on electrical measurements obtained between the contact sensing electrodes (e.g., electrodes D1, D2, D3), as represented by the different hatching in fig. 46A and 47A. The implementation of the graphical color change may be similar to the implementation of the temperature-based contact tip icon coloring described in connection with fig. 43A-44D.

During delivery of ablation energy, the graphical tip icon output is based on temperature measurements between the temperature sensors, and the graphical tip icon 4405 switches to a temperature display mode (e.g., as shown in fig. 43A-44D and described in connection with fig. 43A-44D). For example, the graphical catheter tip icon output in fig. 46B and 47B may be the same as the graphical catheter tip icon output in fig. 44B and 44C, respectively. In certain embodiments, it may be helpful to understand the percentage of the surface of the composite-tip electrode assembly that is in contact with tissue. In some embodiments, the rate of lesion formation and the size of the lesion are directly related to the amount of electrode surface contact, and not necessarily to the magnitude of the contact force.

Another clinically relevant aspect of displaying in real time the voltage and/or frequency of tissue in contact with the catheter tip is for lesion monitoring. In some embodiments, as shown in fig. 46B and 47B, the voltage and/or frequency dynamic scale 4613 continues to be displayed during energy delivery even though contact is no longer determined based on local voltage and/or frequency measurements. When RF energy is initiated, the initial measured voltage and frequency will change as the tissue is ablated. In some embodiments, when the measured voltage and/or frequency on the scale 4613 ceases to change or when the measured voltage and/or frequency decreases to a predetermined threshold level (e.g., 80% of the starting level), the lesion may be assumed to be fully formed and the clinician may decide to stop the RF application. In some embodiments, the measured voltage and/or frequency decreases over time after the initiation of the RF energy. As shown in fig. 46B and 47B, the measured voltage and/or frequency on the dynamic scale 4613 is significantly lower than the measured voltage and/or frequency on the dynamic scale 4613 in fig. 46A and 47A, indicating that the lesion is complete. In some embodiments, the post-ablation voltage is reduced by 50% to 95% and the post-ablation frequency is shifted to 1.0Hz to 15.0 Hz. After this significant voltage and frequency change (e.g., drop) occurs after ablation, if the respective parameters fluctuate by 0% to 10% for at least 5 seconds, an output may be generated to indicate to the clinician that the delivery of ablation energy may be terminated or that ablation energy may be automatically terminated. In other embodiments, the clinician may decide to terminate the delivery of ablation energy based on changes in the displayed dynamic scale 4613 observed over time. In still other arrangements, the graphical display or other output may include a graph showing the rate of change of voltage and frequency over time. Thus, once those plots flatten (e.g., or begin to tend to flatten) such that the voltage and frequency measurements no longer change or change by a significant amount, the clinician or practitioner may choose to terminate the process. In other embodiments, the system may be configured to automatically terminate the process once the slope of such a graph has flattened to a threshold level.

The output indicative of the damage assessment may be dynamically displayed on the graphical tip icon by changing the color of the slider on the scale. For example, the color of the bars on scale 4613 may change (with different colors represented in the figure by different hatch patterns) when the frequency corresponds to a known spectrum of ablated tissue. In some implementations, there may be a dedicated lesion completion icon or output indicator 4622 that indicates to the operator that the target tissue has been sufficiently ablated and that the delivery of energy may be terminated. As one example, output indicator 2622 may be graphically represented as an LED icon that lights up or colors when the measured voltage and/or frequency on one or both of graduations 4613 has reached a threshold level indicating lesion formation (or ablation of tissue). There may also be an audible, tactile (e.g., tactile), and/or any other alarm or indicator to indicate that the injury is complete. In some embodiments, RF energy delivery may be automatically terminated by an energy delivery module (e.g., a processing device of an RF generator) upon indication of lesion completion.

According to several embodiments, the concept of monitoring frequency values may be used to distinguish between living tissue and previously ablated tissue. For example, the color of the graphical tip icon may be configured to change according to the voltage or frequency of the tissue as it is scanned back and forth across the endocardium. Ablated tissue has a unique low voltage and low frequency spectral profile. Thus, the combination of the voltage scale and the frequency scale may advantageously inform the clinician: if there is very low voltage or little voltage but low frequency, they are contacting the ablated tissue.

According to several embodiments, one or more screenshots of the graphical output may be acquired at particular ablation locations or positions during ablation and stored in memory such that the graphical output may be subsequently displayed (e.g., via integration with a mapping/recording system and via some other mechanism, in a pop-up window, such as the pop-up windows described herein, e.g., in paragraphs [0630] to [0666] in connection with fig. 36A-40B, etc.). In some embodiments, information and/or data used to generate the graphical output is stored in addition to or instead of the actual graphical image, such that the graphical output may be rendered on the display at a later time (e.g., after being transmitted to and integrated with the mapping/recording system). Accordingly, the system 10 may be configured to allow a clinician or other user to retrieve information already stored in memory relating to one or more previous ablation procedures at one or more particular ablation locations or positions.

The graphical output (e.g., a two-dimensional or three-dimensional graphical representation, icon or image, etc.) may include a visual representation generated in a graphical user interface by execution of software including executable instructions stored on a non-transitory computer-readable medium by one or more processing devices (e.g., processors 46) connected with an input/output device (as described in connection with fig. 1). The one or more processing devices may be configured such that the generated output is displayed on a display (e.g., an LCD or LED monitor, touchscreen, etc.) in communication with the processing device (e.g., a display of the RF generator or other energy delivery module, a display of a mapping/recording system communicatively coupled to the medical instrument, the processing device, or the energy delivery module (e.g., radio frequency generator), or a separate stand-alone display device (such as an LCD or LED monitor, touchscreen, etc.). In some embodiments, the "real-time" graphical output is transmitted, recalled, or otherwise displayed at a mapping/recording system communicatively coupled to a Medical instrument or generator (e.g., st

Cardiac mapping system, Biosense Webster Inc

3EP System, Boston Scientific

Mapping system, any other electro-anatomical navigation system, etc.), rather than being stored in memory for later display.

As discussed and illustrated herein with reference to some embodiments, the distal end of the ablation catheter may include an electrode having a split orientation. Fig. 48 depicts one embodiment of a system 1100 including such a catheter 1120. As shown, the distal end of the catheter may include an electrode assembly 1130, the electrode assembly 1130 including a distal portion (or distal electrode) 1130a and a proximal portion (or proximal electrode) 1130 b. The distal and proximal portions or electrodes 1130a, 1130b may be electrically coupled to one another at a certain operating frequency using one or more filtering elements (e.g., capacitors) according to various configurations disclosed herein.

With continued reference to fig. 48, the system 1100 may further include one or more ring electrodes 1170A, 1170B, which may be used to obtain and provide additional electrical measurement data to the user during performance of an ablation procedure. In the illustrated embodiment, the catheter 1120 includes a total of two ring electrodes, a distal ring electrode 1170A and a proximal ring electrode 1170B. However, in other configurations, the number of ring electrodes, their size, their location, their relative spacing, and/or other details may be different than shown in fig. 48, as desired or required.

In fig. 48, the distal portion or electrode 1130A of the electrode assembly 1130 is labeled "D1", the proximal portion or electrode 1130b is labeled "D2", and the distal ring electrode 1170A is labeled "D3". As discussed in more detail herein, electrical measurements between "D1" and "D2" and between "D2" and "D3" may be measured and processed. In some embodiments, such electrical data, with or without other data (e.g., temperature), may be used to determine or approximately determine whether contact exists between the electrode assembly and the tissue, the degree, extent, or nature of such contact, the orientation of the electrode assembly relative to the tissue, and so forth, as discussed in more detail herein.

In some embodiments, as discussed in more detail herein, a first gap separates a distal electrode portion or electrode 1130a (also referred to as "D1") from a proximal electrode portion or electrode 1130b (also referred to as "D2") of the electrode assembly. A thermal shunt member or any other member that electrically separates the distal or proximal electrode portions or electrodes 1130a, 1130b may be located within the gap a. In some embodiments, the width of gap A is about 0.2 to 1.0mm (e.g., 0.2-0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6, 0.6-0.7, 0.7-0.8, 0.8-0.9, 0.9-1.0mm, values between the foregoing ranges, less than 0.2mm, greater than 1mm, etc.). In one arrangement, the gap width is 0.5 mm.

According to some embodiments, and to facilitate obtaining additional high resolution electrical data, a distal ring electrode 1170A (also referred to as "D3") may be positioned relatively close to a proximal electrode portion or electrode 1130b (also referred to as "D2"). In some embodiments, the gap width B is about 0.5 to 2.5mm (e.g., 0.5-0.6, 0.6-0.7, 0.7-0.8, 0.8-0.9, 0.9-1.0, 1.0-1.2, 1.2-1.4, 1.4-1.6, 1.6-1.8, 1.8-2.2mm, 2.0-2.5mm, values between the foregoing ranges (less than 0.5mm, greater than 2.5mm, etc.). in one arrangement, the gap width B is 1.0 mm. in another arrangement, the gap width B is 2.0 mm.

In some embodiments, the system may be configured to process electrical, temperature, and/or other data (e.g., obtained by one or more components and/or portions of a catheter) and generate graphical output to provide information to and assist a user (e.g., a clinician). Such output may be displayed (e.g., using a graphical user interface) on a monitor, display, or other output device that may be included within the system or may be separate from the system (e.g., an off-the-shelf product, or other product that the ablation system is not necessarily equipped with or is not necessarily tied to the ablation system). One configuration of such an output is shown in fig. 49A.

As shown in the embodiment of fig. 49A, graphical output 3000 may include one or more panels or portions 3010, 3020, 3030. In the depicted arrangement, output 3000 includes panel 3010, panel 3010 displaying one or more of the following, among others: detected temperature, power, impedance, etc. As shown, such data can be provided in textual form (e.g., real-time values, moving averages, etc.) and/or in graphical form (e.g., values that vary over time), as desired or required. In some embodiments, one or more of the displayed values may comprise a composite value; in other words, the average of the temperature across one or more temperature sensors included along the distal end of the catheter. However, alternatively, a separate value (e.g., temperature value) may be provided for each sensor or parameter detection device or apparatus.

With further reference to fig. 49A, another panel or portion 3020 of the output 3000 may provide a graphical representation of an electrogram between or in relation to any two different electrodes or electrode portions (e.g., electrodes or electrode portions of an ablation electrode assembly, ring electrodes, etc.), as desired or required. Such an output may provide the user with information he or she is looking for, such as, for example, confirming contact of the catheter between a particular location (e.g., between a pair of electrodes being monitored).

Further, as shown in fig. 49A, graphical output 3000 may include a panel or portion 3030, which panel or portion 3030 may advantageously provide a user with information relating to: (1) temperature of the electrode assembly (e.g., temperature of a portion of the assembly or of the assembly as a whole); (2) a level of contact between the electrode assembly and the target tissue; (3) the viability or tissue type of the target tissue (e.g., whether the tissue being targeted is viable or non-viable; in other words, whether the target tissue has been sufficiently or sufficiently ablated); and so on.

In the embodiment shown in fig. 49A, bottom graphical output panel or portion 3030 includes a graphical representation of an electrode assembly (e.g., as a unitary structure). As shown, the graphical representation of the electrode assembly may include one or more different views (e.g., a view in panel 3034 and a view in panel 3036). As discussed in more detail herein, each of the various views of the electrode assembly may be used to provide specific information and/or data to a user of the ablation system. For example, one of the views 3034 may be used to display or represent (e.g., approximate) a level of contact between the electrode assembly and a tissue of the subject (e.g., cardiac tissue). In some embodiments, another view 3036 may show or represent (e.g., approximate) the temperature of the electrode assembly. As discussed herein, in some embodiments, the "temperature" of the electrode assembly may be an average or other approximation of the electrode assembly temperature (e.g., based on various temperature sensors included along the distal end of a system catheter or other medical instrument). Alternatively, however, the temperature may be displayed by a non-uniform representation in the graphical output. For example, the temperature measurement(s) at each longitudinal location of the catheter or other medical instrument may be considered and displayed separately from the measurements at other locations (e.g., as an average of the various temperature sensors at that longitudinal location, a median of the various temperature sensors at that longitudinal location, etc.). Thus, in some embodiments, a representation of the temperature of the electrode assembly may be shown with varying temperatures along the length of the electrode assembly based on such sensor measurements. As shown in fig. 49A, a legend of voltage and/or temperature may be provided along or near each graphical representation of the electrode assembly (e.g., to help a user quickly and easily assess the real-time status of the representation).

Figure 49B shows a representation 3030, which representation 3030 may be provided to a user in an output (e.g., in a graphical user interface) related to the temperature of an electrode assembly (e.g., represented as 3037). As with fig. 49A, the graphical output depicted in fig. 49B may include a legend 3038, which legend 3038 allows a user to quickly and conveniently estimate and evaluate the temperature of the electrode assembly in a corresponding graphical representation 3036 of the electrode assembly. As described herein, the graphical representation 3037 relating to the temperature of the electrode assembly may be a graphical image of a distal portion of an ablation catheter including the electrode assembly represented as a single integral tip. The graphical representation 3037 may be shown at a uniform temperature (e.g., an average value along the entire electrode). Alternatively, representation 3037 may include a gradient that more accurately depicts the difference between temperatures at various locations along the electrode (e.g., distal and proximal and/or lateral differences in temperature). In other words, in one or two directions (e.g., vertical or horizontal as shown in fig. 49B). The gradient may be calculated based on interpolated values determined using temperature values of one or more of the individual temperature sensors located along the electrode assembly.

According to some embodiments, the graphical representation of the ablation electrode or catheter tip displayed on a monitor or other output that may be viewed by a clinician or other practitioner during a procedure may include a halo or similar overlay or layer 3160. As shown in fig. 50, at least a portion 3136 of the display may include a graphical representation of an ablation electrode assembly. In the depicted embodiment, the electrode assembly is shown oriented substantially vertically such that the distal end of the assembly is along the top. However, in other embodiments, the electrode assembly may be depicted differently, as desired or required. In still other embodiments, the orientation of the electrode assembly may be configured to move during use and/or the user may select a desired orientation according to his or her own preferences and desires. A halo or other covering 3160 may extend generally around the periphery of the graphical representation of the electrode assembly, as shown in fig. 50. As discussed in more detail below, such a halo or other overlay 3160 may provide information to a clinician or other user regarding the degree of contact between the electrode assembly and adjacent tissue, the viability of the target tissue, and the like.

With continued reference to fig. 50, the graphical representation of the electrode assembly may include a region 3137 along a distal portion thereof, which region 3137 may provide information regarding the temperature of the electrode assembly and/or the tissue being treated. In some embodiments, such regions 3137 generally correspond to portions of the distal end of the catheter associated with the ablation electrode assembly, as shown in fig. 50. In some embodiments, the graphical representation is configured to display a single temperature along the entire region 3137. However, in other configurations, region 3137 may include a gradient that more accurately indicates the temperature distribution at various locations (e.g., in the longitudinal and/or radial directions) along and/or around the electrode assembly during use. As shown in fig. 50, a temperature legend may be provided alongside or near area 3137 to assist the user in assessing the temperature and its changes (with the hottest temperature being indicated in red and then traveling through the visible spectrum to cooler temperatures, such as orange, yellow, green, blue). The real-time peak temperature (e.g., the maximum temperature of the temperature measurements of the plurality of temperature sensors) may be displayed as a numerical value, a quantitative indicator (e.g., color), and/or a bar or other graph. As shown in fig. 50, the real-time peak temperature is represented graphically and by a color adjacent to the temperature legend. Although the depicted embodiment uses different colors to represent varying temperatures, any other visually distinct identifier (e.g., shaded lines or other textures, other patterns, different intensities/hues of a single color, etc.) may be used instead of or in addition to the different colors.

As shown in FIG. 50, additional data and/or information may be provided on an output to a clinician or other user. For example, the illustrated embodiment includes including certain electrical data in a separate portion 3139 of the output. Such data may include, but is not limited to: a real-time voltage across the electrode pair (e.g., between D1 and D2, between D2 and D3, etc.), a peak voltage across the electrode pair (e.g., between D1 and D2, between D2 and D3, etc.), a change in peak voltage as energy (e.g., radio frequency energy) is being delivered to the electrode assembly, one or more indices, and/or the like. For one or more of such electrical parameters, the output may include a graphical representation of the parameter instead of or in addition to a textual output. For example, in fig. 50, the voltage across the electrode pair (e.g., D1 and D2, D2 and D3, etc.) is provided immediately to the left of the representation of the electrode assembly.

In some embodiments, a halo or other overlay 3160 surrounding the electrode assembly in the output graphical representation may be configured to change color (and/or in some other manner relative to the visual indication) to alert a clinician or other user of the change in the state of the electrode assembly and/or the tissue being treated. For example, in some embodiments, the color of the halo 3160 (and/or another visual indicator) may vary depending on the level of contact between the electrode assembly and tissue (e.g., cardiac tissue). In some embodiments, the color of the halo 3160 (e.g., blue) may be brighter when there is little or no contact between the electrode assembly and the tissue. In one embodiment, the halo 3160 becomes white (or colorless) when there is no contact between the electrode assembly and the tissue. The color of the halo 3160 may be configured to become darker (or different) with greater levels of contact between the electrode assembly and the tissue. Thus, in some embodiments, the brightness or shade of the color of the halo 3160 may be configured to change (e.g., become darker or more vivid) as the level of contact between the electrode assembly and the tissue improves or is otherwise modified. In some embodiments, the color code indicating the contact level may be based on envelope detection, rather than just on peak-to-peak amplitude.

In some embodiments, a visual halo or other covering 3160 around the graphical representation of the electrode assembly on the output device (e.g., monitor) may include two or more discrete portions. For example, the halo 3160 may be divided between the distal portion and the proximal portion. Such different portions may be associated with contact between certain specific portions of the electrode assembly and adjacent tissue. For example, a distal end of the halo or other visual covering 3160 may correspond to and relate to contact between a distal portion of the electrode assembly and tissue, while a proximal end of the halo or other visual covering 3160 may correspond to and relate to contact between a proximal portion of the electrode assembly and tissue. Thus, in such embodiments, by looking at the halo or other visual overlay 3160 and its changes, a clinician or other user can easily and quickly determine whether there is sufficient contact between the electrode assembly and the tissue, what type of contact is present (e.g., strong or weak), the orientation of the electrode assembly (e.g., parallel, perpendicular, oblique with respect to the tissue), and so forth. Further, in some arrangements, the halo 3160 may inform the user of the status of the tissue being treated (e.g., whether the target tissue is live, whether a lesion may have formed, etc.).

According to some embodiments, a halo or other visual overlay 3160 (which may provide information to a user regarding contact and/or tissue viability) may be generated by processing electrical data obtained by or between one or more of the electrodes positioned along the distal end of a catheter or other medical device of an ablation system. In some embodiments, the voltage across the distal and proximal electrodes or electrode portions 1130a, 1130b (or D1 and D2) of the electrode assembly 1130 is measured (see, e.g., fig. 48). Depending on the measured voltage across the electrode or electrode portion, the system may determine whether there is sufficient contact between the electrode assembly (along the electrode or electrode portion whose voltage is being measured) and the adjacent tissue. In some arrangements, the threshold measured voltage indicative of sufficient contact between the electrode assembly and the tissue is about 0.30 mV. In some embodiments, the threshold measured voltage indicative of sufficient contact between the electrode assembly and the tissue is 0.15mV to 0.45mV (e.g., 0.15-0.2, 0.2-0.25, 0.25-0.3, 0.3-0.35, 0.35-0.4, 0.4-0.45, 0.3-0.4, 0.25-0.35mV, 0.3-0.4mV, values in between the foregoing, etc.).

In some embodiments, when the voltage measurement between two electrodes or two electrode portions (e.g., D1 and D2 or two electrodes or electrode portions of an ablation assembly, D2 and D2, etc.) is at or falls below a particular threshold (e.g., equal to or about 0.30mV), the system may conclude that contact between the corresponding portion or region of the catheter and the tissue is insufficient. This determination may take a variety of forms. For example, depending on the actual voltage measurement, the system may determine and indicate "no contact" between the portion of the catheter and the tissue, or it may determine that there is contact between the portion of the catheter and the tissue, but that the contact is weak or insufficient (e.g., below a necessary or desired threshold for the purpose of initiating an ablation procedure or for effectively forming a lesion). Likewise, if the voltage is below or drops below a particular threshold (e.g., equal to or about 0.30mV), the system may interpret such measurements as measurements indicative of ablated tissue (e.g., tissue that has formed a desired lesion or is no longer viable).

Likewise, when the voltage measurement between the two electrodes or two electrode portions is equal to or above a particular threshold (e.g., equal to or about 0.30mV), the system may conclude that contact between the corresponding portion or region of the catheter and the tissue is sufficient (e.g., there is sufficient and appropriate contact as a premise for initiating the energy delivery and ablation process). Such measurements may also indicate that the target tissue in contact with the corresponding portion of the catheter is living and has not been ablated (e.g., there is no lesion at that location of the tissue).

According to some embodiments, as described above, the halo or other visual overlay 3160 that at least partially surrounds the graphical representation of the electrode assembly on the display or other output may be divided into two or more portions or sections. In some arrangements, the halo 3160 is divided into a distal half and a proximal half. However, in other embodiments, the halo may be split into additional portions or sections, some of which may or may not be equal to each other. In one configuration, voltage measurements along the distal end of a catheter or other medical instrument are obtained and processed. For example, with reference to the embodiment of the ablation system shown in fig. 48, voltage measurements may be obtained between electrodes/electrode portions D1 and D2 (the two electrodes or electrode portions 1130A, 1130b of the electrode assembly) and between D2 and D3 (the proximal electrode or electrode portion of the electrode assembly 1130b and the distal ring electrode 1170A). In some embodiments, if the voltage measurements across two electrode pairs (e.g., between D1 and D2 and between D3 and D3) are below a particular threshold (e.g., 0.30mV), the system may be configured to determine that there is insufficient contact between the electrode assembly and the tissue and/or that the tissue being targeted has been ablated. Likewise, if the voltage measurements across two electrode pairs (e.g., between D1 and D2 and between D3 and D3) are equal to or above a particular threshold (e.g., 0.30mV), the system may be configured to determine that there is sufficient contact between the electrode assembly and the tissue and/or that the tissue being targeted is living (e.g., has not been ablated). By using voltage measurements to determine the level of contact rather than force measurements, safe, light contact ablation can be performed without the user having to press with more force to ensure sufficient contact, which may result in perforation or damage to the tissue.

In some embodiments, the system is configured to recognize that the measured voltages across the two pairs of electrodes (e.g., D1 and D2 and D2 and D3) may be different from each other. This may indicate that the contact between the electrode assembly and the tissue varies along the length of the electrode assembly. As discussed in more detail herein, this variability may help the system determine and display (e.g., via a halo or other visual overlay) the orientation of the electrode assembly relative to adjacent tissue. For example, the data may be processed and the graphical representation (e.g., including the use of a halo or other visual overlay) may assist a clinician or other user in determining whether the electrode assembly includes a parallel orientation relative to the tissue, a perpendicular orientation relative to the tissue, an oblique orientation relative to the tissue, which portion(s) of the electrode assembly are making sufficient contact with the tissue, and so forth.

Fig. 51A illustrates one embodiment of a graphical representation 3136A of an electrode assembly, the graphical representation 3136A including a halo or other visual overlay 3160A. In the depicted arrangement, there is no contact between the electrode assembly and the tissue. Thus, the clinician or other user is alerted to the "no contact" condition via the color or other visual indication of the halo 3136A. For example, in some embodiments, when insufficient contact between the electrode assembly and the tissue is determined, the halo or other covering 3160A is white or another bright color. In the illustrated embodiment, there is insufficient tissue contact along both the distal and proximal portions of the electrode (e.g., as determined by voltage measurements across the D1 and D2 electrodes and across the D2 and D3 electrodes, as discussed above).

In several embodiments disclosed herein, different colors are used in the graphical output to represent differences in electrode-tissue contact, tissue viability, temperature, impedance, and/or one or more other parameters. However, in other embodiments, other visual indications instead of or in addition to color may be used to inform a clinician or other user of relevant information. Such other indicia may include, but are not limited to: different shades and/or tones of the same color, different contrast or brightness levels, shading or other patterns, and the like.

As described above, with continued reference to fig. 51A, the "no touch" determination of the system may be displayed in a halo or other visual overlay 3160A that includes bright colors (e.g., white, gray, etc.). Alternatively, any other color or visual indication may be used, as discussed in the preceding paragraph. In some embodiments, when there is sufficient contact between the electrode assembly and the ablated (e.g., non-living) tissue, the halo or other visual overlay 3160A will be the same as the "no contact" scenario. Thus, in some arrangements, a clinician may need to distinguish between a "no-contact" condition and a scenario in which non-living tissue is in contact in one or more other ways. For example, a clinician can typically determine whether there is tissue contact with the distal end of the catheter based on the resistance and tactile feedback felt while manipulating the catheter.

The embodiment shown in fig. 51B depicts a situation in which a stronger contact between the electrode assembly and tissue along the proximal portion of the electrode assembly is indicated based on the graphical output 3136B (including the halo 3160B). For example, in the depicted arrangement, the color (or other visual indication) is different along the proximal half of the halo or other visual overlay 3160B-2 relative to the distal half of the halo 3160B-1. In some embodiments, the proximal half of the halo or other visual overlay 3160B-2 comprises a blue color that is darker than the brighter blue color along the distal half of the halo 3160B-1. Of course, as discussed herein, any other color scheme or other visual indication may be used to indicate a difference in contact between the electrode assembly and the tissue, as desired or required. According to some embodiments, the visual representation of the halo 3160B shown in fig. 51B informs the clinician or other user of the following: there is generally parallel contact between the electrode assembly and the tissue, with better contact along the proximal portion of the electrode assembly. As a result, when the clinician positions the ablation catheter within the target region of the subject, he or she can easily and quickly visually determine the orientation of the electrode assembly relative to the tissue via the graphical representation 3160 on the monitor or other output.

Fig. 51C shows a graphical representation 3136C, where a halo or other covering 3160C indicates that there is better electrode assembly-tissue contact along the distal end of the electrode assembly relative to the proximal end. As shown, in some embodiments, the area of the distal portion 3160C-1 of the halo 3160C may be darker and/or may be otherwise distinguished from the area of the proximal portion 3160C-2 of the halo to inform the clinician of better contact between the electrode assembly along the distal end of the catheter and the tissue. In fig. 51D, the halo or other covering 3160D is generally uniform along both the distal and proximal portions, and its color (or other visual scheme) indicates that there is sufficient contact between the electrode assembly and the tissue along both the distal and proximal portions of the electrode assembly. Thus, in such embodiments, the clinician or other user is informed that the electrode assembly includes an orientation that is substantially parallel with respect to the tissue (e.g., due to the seemingly similar contact along the entire length of the electrode assembly).

According to some embodiments, the system may be configured to display the halo or other visual covering 3160 of the distal portion differently than the proximal portion even where both the distal portion and the proximal portion have met a threshold contact requirement (e.g., with respect to the voltage across the electrodes or electrode portions, as discussed herein). For example, in some arrangements, blue color on the halo 3160 may be used to show satisfactory tissue contact. Depending on whether one portion (e.g., the distal half, the proximal half, etc.) of the electrode assembly exhibits better contact with adjacent tissue (e.g., as determined by voltage measurements obtained from electrodes or electrode portions positioned along a corresponding portion of the electrode assembly), the darkness or hue of the color (blue) representing the contact may vary along the halo or other visual covering 3160 for two or more portions (e.g., halves). For example, as shown in fig. 51B, the distal half 3160B-1 of the halo 3160B includes a brighter shade of blue than the proximal half 3160B-2 of the halo, which indicates that, while the electrode assembly is contacting tissue along its entire length, the contact between the proximal portion of the electrode assembly and the tissue is better than the contact between the distal portion and the tissue. As discussed above with reference to fig. 51B, this informs the user that the orientation of the electrode assembly relative to the tissue is not perfectly parallel (e.g., is typically tilted relative thereto, wherein the proximal end of the electrode assembly makes better contact with the tissue than the distal end).

According to some embodiments, the system may be configured to assign different colors (e.g., different darkness levels or hues, different shadows, etc.) and/or some other visual distinction between two or more portions (e.g., the distal half, the proximal half) of the halo 3160 based on a comparison of voltages obtained by corresponding electrode pairs located in different portions of the electrode assembly. For example, referring to the embodiment shown in fig. 48, the system is designed and configured to obtain voltage measurements between (1) D1 and D2 and (2) D2 and D3. As discussed above, the spacing of the electrode pairs is selected to enable local and reliable voltage data to be obtained to better assess the level of contact between the corresponding electrode pair and adjacent tissue.

In some embodiments, for example, assuming that it is determined that both the distal portion and the proximal portion of the electrode assembly are sufficiently in contact with tissue (e.g., the voltage across the corresponding electrode pair satisfies a threshold voltage, e.g., 0.30mV), if the voltage measured across D1 and D2 is greater than 30% relative to the voltage measured across D2 and D3, the color or other visual identifier assigned to the distal half of the halo 3160 will be different (e.g., darker) than the color or other visual identifier assigned to the proximal half of the halo, and vice versa. In some embodiments, a different color or identifier is used when the relative difference between the voltage measurements across two electrode pairs is different than 30%. For example, such a percentage difference that triggers a visual difference (e.g., a color difference) in a corresponding portion of the halo 3160 may be between 20% and 40% (e.g., 20-25, 25-30, 30-35, 35-40%, percentages between the foregoing, etc.), less than or equal to 20%, greater than or equal to 40%, as desired or required.

In some embodiments, if the voltage measurement across any pair of electrodes is unstable, the color or other visual representation of the halo 3160 may visually change, thereby suggesting to a clinician or other user that sufficient electrode-tissue contact has not been achieved. For example, in some arrangements, if the voltage recording changes by more than 5% when the voltage measurement is obtained and processed, the shade of color in the halo (e.g., blue) representing the contact may change (e.g., rapidly). Any other method of alerting the user to a potentially unstable voltage reading may be included in the visual display, including but not limited to flashing, blinking, pixelating, and the like, instead of or in addition to a color change. The percentage fluctuation of the voltage measurement that can trigger such an alarm may be different from 5%. For example, the percentage can be 1% to 10% (e.g., 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10%, percentages therebetween, etc.), greater than 10% (e.g., 10-12, 12-14, 14-16, 16-18, 18-20, 15%, percentages therebetween, greater than 20%, less than 1%, as desired or required.

In some embodiments, the halo or other visual overlay 3160 surrounding the graphical representation of the electrode assembly on the display or other output may vary along the extent of the electrode assembly without having different portions or sections. For example, in the foregoing discussion relating to fig. 51A-51D, the halo 3160 is divided into a distal half and a proximal half (e.g., corresponding to voltage measurements taken at the D1 and D2 electrodes and at the D2 and D3 electrodes, respectively). However, in alternative embodiments, as shown in fig. 53B-53D, the halo or other visual covering 3260 may vary along the length of the graphical representation of the electrode assembly without having different portions or sections. Thus, in some embodiments, the range, color, intensity, and/or other visual characteristics of the halo may be varied to indicate varying degrees of tissue contact along various portions of the electrode assembly.

Referring to fig. 52, the graphical representation 3236 of the electrode assembly does not include a halo or other visual covering therearound. In some embodiments, the absence of a halo or other visual covering indicates that there is not sufficient contact between the electrode assembly and the tissue. As discussed herein, such a determination may be based on a voltage measurement across an electrode pair located at or near the electrode assembly.

Fig. 53A illustrates an embodiment of a graphical output 3236A in which a halo 3260A is generally uniform around the entire electrode, thereby alerting a clinician or other user that sufficient contact is present along both the distal and proximal ends of the electrode assembly. Such a configuration may therefore inform the user that the electrode assembly has a substantially parallel orientation with respect to the tissue.

In fig. 53B-53D, the level of contact between the electrode assembly and the tissue varies along the length of the electrode assembly. The clinician or other user is informed of this fact in a corresponding graphical representation by the shape, intensity, extent, and/or other visual differences of the halo 3260 that vary along the length of the electrode assembly. For example, in the graphical representation 3236B of fig. 53B, the halo 3260 is more intense (e.g., with respect to color, brightness, contrast, etc.) along the distal end of the electrode assembly. However, in this arrangement, there still appears to be sufficient or sufficient contact along the proximal end of the electrode assembly, as indicated by the halo of lesser intensity along that region of the assembly. When encountering such a graphical representation, the clinician can readily understand that: contact between the electrode assembly and the tissue is stronger or better along the distal end of the assembly relative to the proximal end.

Fig. 53C shows an embodiment of a graphical representation 3236C of an electrode assembly, which is generally the reverse of the representation in fig. 53B. In other words, the halo 3260C in fig. 53C is more intense (e.g., with respect to color, brightness, contrast, etc.) along the proximal end of the electrode assembly. Thus, when encountering such a graphical representation, the clinician can readily understand that: contact between the electrode assembly and the tissue is stronger or better along the proximal end of the assembly relative to the distal end. Fig. 53D illustrates an embodiment of a graphical output 3236D in which a halo 3260D is placed primarily along and around the distal end of the electrode assembly representation. Thus, in this configuration, the clinician may be informed that contact between the electrode assembly and tissue is occurring along the distal end of the electrode assembly, thereby indicating vertical or substantially vertical contact between the assembly and the target tissue.

In some embodiments, when the tissue being contacted by the electrode assembly is non-viable (e.g., a lesion has formed or the tissue has been sufficiently ablated), a halo may be absent from the graphical representation of the electrode assembly on the display or other output. For example, fig. 53E shows a graphical representation 3236E of an electrode assembly without halo present. As discussed previously, a clinician or other user can typically determine whether the tip of a catheter or other medical device used to perform an ablation procedure is in contact with tissue (e.g., based on tactile feedback when manipulating the catheter). In the embodiment of fig. 53E, another visual indicator that helps the user to conclude is the temperature of the electrode: the electrode assembly is in contact with tissue that has been ablated. In the illustrated embodiment, the temperature of the electrode assembly may be represented by the color and/or other visual scheme 3237E of the representation attached to the assembly. Thus, in some embodiments, fig. 53E may indicate the following scenario: the clinician has delivered sufficient ablation energy to the electrode assembly after ensuring that there is sufficient contact between the electrode assembly and the target tissue. In other words, fig. 53E may represent a graphical output at the end of an ablation procedure. In some embodiments, the initial (pre-ablation) graphical output will include a halo or other visual overlay (e.g., representing sufficient contact with tissue) around at least a portion of the electrode. As energy is delivered to the electrode assembly and surrounding tissue begins to form lesions, the temperature of the electrode will increase (e.g., as indicated by a change in color or other visual identifier within region 3237E representing the electrode assembly). At the same time, when tissue begins to become inactive, the halo (e.g., its color, intensity, range, etc.) will begin to diminish because the voltage measurement across such tissue will decrease.

Fig. 53F illustrates one embodiment of a graphical output 3236F in which the halo 3260F is relatively weak and is located only along the proximal end of the electrode assembly. In some embodiments, this represents the following: the distal end of the assembly is in contact with the tissue that has been ablated while the proximal end of the assembly is in contact with the tissue that is still viable.

As shown in fig. 49B-53F, the graphical representation of the electrode assembly may be configured to display the real-time temperature of the assembly (e.g., along an interior region defined by the graphical representations of the assemblies 3037, 3137A-D, 3237A-F). In some embodiments, the temperature of the electrode comprises an average temperature of all sensors that obtain the temperature measurement. Thus, the representation of the electrode assembly may include a single color or other visual representation that indicates the average temperature of the assembly (and/or the temperature of the adjacent tissue with which the electrode assembly is contacting). In other embodiments, as shown in fig. 53E and 53F, the color and/or other visual indicators of the temperature along the area represented by the assembly may vary (e.g., may show a temperature gradient along one or more directions of the assembly that represents the actual temperature measurement of the various sensors).

According to some embodiments, any of the electrode assembly graphical renderings or representations disclosed herein (such as, for example, those shown in fig. 43A-44D, fig. 46A-47B, and fig. 49A-54D) may be configured to be displayed on a mapping and navigation system. In some embodiments, the real-time voltages obtained across one or more pairs of electrodes (e.g., D1 and D2, D2 and D3, etc.), real-time temperatures (e.g., average temperature measurements from all sensors, individual temperature measurements, etc.), and/or any other data and/or information may be displayed on and otherwise incorporated into the mapping and navigation system. In some arrangements, the electrode assembly rendered tip electrode displayed within the three-dimensional electro-anatomical model may have the same functionality as the independent contact module system. Thus, the necessary hardware and/or software components within a separate module may be incorporated into the mapping and navigation system.

According to some embodiments, when an electrode assembly is determined to be in contact with tissue (e.g., based on a voltage measurement, as described herein) based on a rendered or graphical representation of the electrode assembly (according to any of the arrangements disclosed herein or an equivalent thereof), the corresponding tissue may be represented as a blue color (or another color or visual indicator) in the mapping and navigation system output. When a practitioner or other user initiates energy delivery to the electrode assembly, the color of the electrode assembly graphical representation or other visual indicia of the color (e.g., such as those described herein with reference to fig. 49A-54D) will change to track the real-time temperature readings of the sensors along the electrodes (e.g., measure the temperature of adjacent tissue, blood, etc.). In some arrangements, once voltage measurements obtained along one or more electrode pairs confirm that necrosis or lesion formation has occurred (e.g., when the voltage drops below 0.30mV or another threshold level), a color (e.g., blue) or other visual indicator representing tissue on the mapping and navigation system may change (e.g., turn red). The tip of the ablation catheter may then be moved to an adjacent desired location within the anatomy to form additional lesions. In some embodiments, this process is repeated until a complete pattern of lesions is created that meets the desires and requirements of the clinician. One embodiment of points visually added to the mapping and navigation system output is shown in fig. 37A and 37B. In some arrangements, the treatment site is given a red color or other visual indication of ablation completion to help the clinician determine how the lesion is being formed and where to position the electrode for additional ablation.

In some embodiments, certain data is included in each ablation point, which is added to the output of the mapping and navigation system. For example, a measured tissue voltage (or peak, average, and/or other voltage measurement) at the end of a single ablation point, a temperature of the tissue based on sensor measurements (e.g., average, maximum, and/or other measurement data) at that location, a duration or time of energy delivery, and/or any other parameter may be associated with each ablation point. In some embodiments, a user may easily access such data associated with each ablation point (e.g., by moving a pointer or other user-controlled device over each point). In some embodiments, an index may be created that evaluates the effectiveness, extent, and/or other characteristics of the ablation point. For example, such indicators may be determined at least in part using time, temperature, voltage, and the like.

According to some arrangements, once a lesion or ablated line is created, a practitioner or other user may move the electrode assembly along or near the ablated line to investigate and confirm that the lesion has been properly formed, or to identify a gap or break in the "lesion line". For example, if the clinician determines that one or more regions along the "lesion line" are not already properly ablated (e.g., based on voltage measurements), he or she may make additional ablation points.

The graphical output may be further supplemented in order to provide additional guidance to the clinician during the execution of the lesion formation procedure. For example, as shown in fig. 54A-54D, the visual representation of the electrode assembly may include an outer frame or border 3390A. In some embodiments, the color and/or one or more other visual indications (e.g., pattern, brightness, shading, intensity, etc.) of the frame 3390A may change during the course. Such features may provide additional information to the clinician to assist him or her in performing the ablation procedure correctly and safely.

For example, in some arrangements, the frame 3390 may include a black or other desired color or visual scheme prior to delivering any energy (e.g., RF) to the electrode assembly. As shown in fig. 54A, the color of the frame 3390A may change color to white (or another desired color or visual scheme) when energy delivery to the electrode assembly is initiated and one or more other criteria are met. For example, in some embodiments, the frame 3390A turns white when energy delivery is initiated and (1) the voltage measured across one or more electrode pairs is above a particular first threshold (e.g., 0.30mV) and (2) the temperature detected by sensors along the electrode assembly (e.g., indicating electrode and/or tissue temperature) is below a particular first temperature threshold (e.g., 44 degrees celsius). In some embodiments, if energy is delivered to the electrode assembly, but the voltage measurement is below a first threshold (e.g., below 0.30mV), the system may be configured to visually notify the clinician. This scenario may occur, for example, when contact between the electrodes and the tissue is not appropriate. For example, in some embodiments, in those cases, the frame 3390A may remain the same color (e.g., white), but may begin to flash. Alternatively, the frame 3390A may change color and/or be modified in one or more other visual ways to alert the user.

Referring to fig. 54B, when the system determines that a lesion has begun to form, the frame 3390B may change color (e.g., from white to green, from a first color to any other color, etc.) and/or otherwise change visually (e.g., pattern, hue, shade, intensity, brightness, etc.). For example, in some embodiments, such a change in the frame 3390B may occur when energy delivery to the electrode assembly is recovering and certain criteria related to voltage and temperature are met. In some embodiments, when the voltage is greater than a particular second voltage threshold and the temperature is greater than a particular second temperature threshold, the frame 3390B will be changed to confirm that lesion formation has been initiated. In some embodiments, the first and second voltage and/or temperature thresholds may be the same. However, in other embodiments, the first and second thresholds are different. In one configuration, the frame color changes (e.g., from white to green) when RF energy is being delivered to the electrode assembly, voltage measurements exceed 0.30mV, and temperature measurements exceed 44 degrees celsius. As shown in fig. 54B, once the formation of the damage begins and the voltage begins to drop, the visual representation (e.g., shape, size, extent, etc.) of the halo will begin to change (e.g., assume a smaller shape or size).

In some embodiments, as shown in fig. 54C, the frame 3390C is configured to change color again (or in some other visual manner) to alert a clinician or other user that the ablation process (e.g., lesion formation at the target tissue location) is near completion. As shown, this change in state (e.g., from a green to yellow frame) may be configured to occur when ablation energy continues to be delivered to the electrode assembly and certain criteria are met. For example, in some embodiments, the criteria that need to be met to trigger such an event or change the color and/or other visual representation of the frame include: (1) a temperature detected by the one or more sensors (e.g., a temperature of the electrode assembly, adjacent tissue, etc.) exceeds a particular threshold (e.g., 44 degrees celsius), and (2) a voltage measured along the one or more electrodes is within a particular target range (e.g., 0.30mV, 0.20 and 0.25mV, ranges therebetween, etc.). As shown in fig. 54C, the size of the halo will continue to change (e.g., it will continue to become smaller) as the living tissue continues to ablate.

In some cases, when the formation of the lesion is deemed "complete" (e.g., according to some predetermined criteria), the frame may be configured to change the color and/or visual scheme again. In one arrangement, as shown in fig. 54D, the frame 3390D may change the visual scheme again (e.g., to red or to another color, change as desired or required with respect to another visual scheme, etc.). Such a change may advantageously inform the clinician or other user that the ablation procedure should be terminated, as the lesion appears to have formed according to certain criteria. For example, in some configurations, the frame 3390D may turn red (or otherwise visually change) when energy continues to be delivered to the electrode assembly and (1) the voltage measured across one or more electrode pairs located at or near the assembly is below a pre-specified ablation threshold (e.g., 0.30mV) and (2) the temperature detected by a sensor at the electrode assembly is above a lesion formation threshold (e.g., 44 degrees celsius). . In certain embodiments, if energy delivery continues after confirmation of lesion formation has been provided (e.g., via a frame color change to, for example, red), the system may be configured to alert the clinician to this condition. For example, in some arrangements, the system may be configured to flash a frame (e.g., a frame that has changed to red). Such an alert may help inform the clinician that the lesion has fully developed and that energy delivery should be terminated immediately to prevent charring or other damage to the subject. As shown in fig. 54D, when the desired lesion has formed in the target tissue and/or the desired or required level of ablation has been produced to the subject, the halo around the graphical representation of the electrode assembly disappears because the recorded voltage measurements have fallen below the threshold for good contact and/or living tissue contact. According to several embodiments, implementations of the contact level and tissue viability approaches and methods described herein advantageously allow clinicians to perform ablation procedures based on real data rather than on arbitrary configurations based on predictions or models or algorithms. The methods described herein are based on real-time accurate measurements rather than any "one-size-fits-all" type of method or model-based method, accurately guiding the clinician when to start and stop the ablation process, thereby enhancing safety and efficacy.

In some embodiments, the temperature color (or other visual indication or representation) along the graphical image of the electrode assembly may inform about how quickly a lesion will form, the local blood flow conditions around the tip, whether the tip is slipping or losing contact, whether the tip is buried in tissue, and/or other data and information that may facilitate a clinician in performing an ablation procedure.

According to some arrangements in which a halo or other covering is used, when attempting to create a continuous drag (drag) lesion, energy may be delivered before the halo disappears. In embodiments such as those described herein with reference to fig. 54A-54D, once the frame alerts the user about the appropriate ablation (e.g., by flashing red), the clinician may drag the tip to the next point so that the halo reappears on the graphical representation of the electrode assembly. This process may be repeated using dragging or similar techniques to create lesions with multiple ablation points. In some embodiments, when ablating in thin tissue, the halo may disappear and the progression of the graphical representation change (e.g., from fig. 54A to 54D) may be completed in a few seconds (e.g., 1 to 10 seconds (e.g., 2 to 8, 4 to 6, 1 to 2, 2 to 3, 3 to 4, 4 to 5, 5 to 6, 6 to 7, 7 to 8, 8 to 9, 9 to 10 seconds, values between the aforementioned ranges, etc.).

According to some configurations, because the measurements are based on actual real-time tissue data, any of the graphical output embodiments disclosed herein can be used to perform faster ablation without safety or efficacy concerns (or with reduced safety and/or efficacy concerns). As a result, "continuous" rapid ablation can be performed by: rapidly increasing power and maintaining for a short time at each location by monitoring the pattern output. In some embodiments, the time of ablation (e.g., from the beginning to the end of energy delivery) can be reduced by about half or more than half (e.g., 30-70, 40-60, 60-80, 50-100, 20-100, 0-20, 20-40, 40-60, 60-80, 80-100%, percentages in between, etc.) relative to the prior art.

In some embodiments, the system comprises one or more of: means for tissue modulation (e.g., an ablation or other type of modulation catheter or delivery device), means for generating energy (e.g., a generator or other energy delivery module), means for connecting the means for generating energy to the means for tissue modulation (e.g., an interface or input/output connector or other coupling member), means for performing tissue contact sensing and/or tissue type determination, means for displaying output generated by the means for performing tissue contact sensing and/or tissue type determination, means for determining a level of contact with tissue, means for calibrating network parameter measurements connected with the contact sensing means, and the like.

In some embodiments, a system includes various features that exist as a single feature (as opposed to multiple features). For example, in one embodiment, the system includes a single ablation catheter with a single high resolution (e.g., compound, e.g., split tip) electrode and one or more temperature sensors (e.g., thermocouples) to help determine the temperature of the tissue at a depth. The system may include an impedance transformation network. In some embodiments, the system includes a single ablation catheter with a thermal shunt network for transferring heat away from the electrodes and/or tissue to be treated. In some embodiments, the system includes a single contact sensing subsystem for determining whether and to what extent contact is present between the electrodes and the target tissue of the subject. In alternative embodiments, multiple features or components are provided.

In one embodiment, the system comprises one or more of: means for tissue modulation (e.g., ablation or other type of modulation catheter or delivery device), means for generating energy (e.g., a generator or other energy delivery module), and/or means for connecting the means for generating energy to the means for tissue modulation (e.g., an interface or input/output connector or other coupling member), etc.

In some embodiments, the system comprises one or more of: means for tissue modulation (e.g., an ablation or other type of modulation catheter or delivery device), means for measuring tissue temperature at a depth (e.g., using a plurality of temperature sensors (e.g., thermocouples) thermally insulated from the electrodes and positioned along two different longitudinal portions of the catheter), means for efficiently transferring heat away from the electrodes and/or tissue to be treated (e.g., using thermal shunt materials and components), and means for determining whether and to what extent contact exists between the electrodes and adjacent tissue (e.g., using impedance measurements obtained from high resolution electrodes also configured to ablate tissue).

In some embodiments, the system comprises one or more of: the ablation system consists essentially of: a catheter, an ablation member (e.g., an RF electrode, a composite (e.g., split tip) electrode, another type of high resolution electrode, etc.), an irrigation conduit extending through the interior of the catheter to or near the ablation member, at least one electrical conductor (e.g., a wire, cable, etc.) for selectively activating the ablation member, and at least one heat transfer member that places at least a portion of the ablation member (e.g., a proximal portion of the ablation member) in thermal communication with the irrigation conduit, at least one thermal shunt member configured to effectively transfer heat away from the electrode and/or tissue being treated, a plurality of temperature sensors (e.g., thermocouples) positioned along two different longitudinal locations of the catheter, a contact detection subsystem for determining whether and to what extent contact exists between the electrode and adjacent tissue (e.g., using impedance measurements obtained from the high resolution electrode also configured to ablate tissue), and the like Wherein the temperature sensor is thermally isolated from the electrode and configured to detect a temperature of tissue at a depth.

In the above disclosed embodiments, a heat transfer member is disclosed. Alternatively, in some embodiments, a heat retainer is used instead of or in addition to the heat transfer member.

Any of the methods described herein may be embodied in and partially or fully automated via a software code module (e.g., in the form of an algorithm or machine-readable instructions) stored in a memory or tangible, non-transitory computer-readable medium executed by one or more processors or other computing devices. The software may be downloaded to the processor in electronic form. In embodiments involving multiple processors, the processors may operate in parallel to form a parallel processing system in which the process is divided into portions that are executed simultaneously on different processors of the ablation system. The method may be performed on a computing device in response to execution of software instructions or other executable machine-readable code read from a tangible computer-readable medium. The tangible computer readable medium is a data storage device that can store data that can be read by a computer system. Examples of a computer-readable medium include read-only memory (e.g., ROM or PROM, EEPROM), random-access memory, other volatile or non-volatile memory devices, CD-ROMs, magnetic tape, flash drives, and optical data storage devices. The modules described herein (e.g., contact detection, evaluation, or sensing modules) may include structural hardware elements and/or non-structural software elements (e.g., algorithms or machine-readable instructions executable by a processing or computing device) stored in memory.

Additionally, embodiments may be implemented as computer-executable instructions stored in one or more tangible computer storage media. As will be appreciated by those of ordinary skill in the art, such computer-executable instructions stored in tangible computer storage media define specific functions to be performed by computer hardware, such as a computer processor. Typically, in such implementations, the computer-executable instructions are loaded into a memory accessible by at least one computer processor (e.g., a programmable microprocessor or microcontroller or application specific integrated circuit). The at least one computer processor then executes the instructions, causing the computer hardware to perform the specific functions defined by the computer-executable instructions. As will be appreciated by one of ordinary skill in the art, computer execution of computer-executable instructions is equivalent to the execution of the same functions by electronic hardware that includes hardware circuitry that is hardwired to perform the specific functions. Thus, while the embodiments illustrated herein are typically implemented as some combination of computer hardware and computer-executable instructions, the embodiments illustrated herein may also be implemented as one or more electronic circuits that are hardwired to perform the specific functions illustrated herein.

Various systems, devices, and/or related methods disclosed herein may be used to at least partially ablate and/or otherwise ablate, heat, or otherwise thermally treat one or more portions of a subject's anatomy, including but not limited to: cardiac tissue (e.g., myocardium, atrial tissue, ventricular tissue, valves, etc.), body cavities (e.g., veins, arteries, airways, esophagus or other digestive tract lumens, urethra and/or other urinary tract vessels or lumens, other lumens, etc.), sphincters, prostate, baby, gall bladder, uterus, other organs, tumors and/or other growths (growths), neural tissue, and/or any other portion of the anatomy. Selective ablation and/or other heating of such anatomical locations may be used to treat one or more diseases or conditions, including, for example, atrial fibrillation (sustained or episodic), atrial flutter, ventricular tachycardia, mitral regurgitation, other heart diseases, asthma, Chronic Obstructive Pulmonary Disease (COPD), other pulmonary or respiratory diseases (including benign or cancerous lung nodules), hypertension, heart failure, denervation, renal failure, obesity, diabetes, gastroesophageal reflux disease (GERD), other gastrointestinal diseases, other neurological diseases, tumors or other growths, pain, and/or any other disease, condition or disease.

In any of the embodiments disclosed herein, one or more components (including a processor, computer-readable medium or other memory, a controller (e.g., dials, switches, knobs, etc.), a contact sensing subsystem, a display (e.g., a temperature display timer, etc.) are incorporated into and/or coupled (e.g., reversibly or irreversibly) with one or more of the following: a generator, an irrigation system (e.g., irrigation pump, reservoir, etc.), and/or any other portion of an ablation or other modulation or therapy system.

Although several embodiments and examples are disclosed herein, the present application extends beyond the scope of the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and modifications and equivalents thereof. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. Thus, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed inventions. The headings used herein are provided solely for the purpose of enhancing readability and are not intended to limit the scope of the embodiments disclosed in the specific section to the features or elements disclosed in that section.

While the embodiments disclosed herein are susceptible to various modifications and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the invention is not to be limited to the particular forms or methods disclosed, but to the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the various embodiments described and the appended claims. Any methods disclosed herein do not have to be performed in the order recited. The methods disclosed herein include certain actions taken by the practitioner; however, they may also contain any third party instructions for these actions, whether explicit or implicit. For example, actions such as "advancing a catheter" or "delivering energy to an ablation member" include "instructing to advance a catheter" or "instructing to deliver energy to an ablation member," respectively. The ranges disclosed herein also encompass any and all overlaps, sub-ranges, and combinations thereof. Language such as "up to," at least, "" greater than, "" less than, "" between. Numerals following terms such as "about" or "approximately" include the recited numerals. For example, "about 10 mm" includes "10 mm". A term or phrase following a term such as "substantially" includes the recited term or phrase. For example, "substantially parallel" includes "parallel".

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