阅读说明：本技术 局部缺血的治疗 (Treatment of ischemia ) 是由 F·多兰 H·奥多诺霍 于 2019-11-06 设计创作，主要内容包括：一种用于穿过血管中的阻塞物的血管内设备包括细长血管内线材和联接件。使用时,所述联接件将超声能量从超声能量源沿着所述线材传输到所述线材的远侧端部处的有源尖端。所述联接件被布置成在沿着所述线材的长度的多个离散操作位置中的任一者处将所述源联接到所述线材以用于超声能量到所述有源尖端的所述传输。(An intravascular device for traversing an obstruction in a blood vessel includes an elongate intravascular wire and a coupling. In use, the coupling transmits ultrasonic energy from an ultrasonic energy source along the wire to an active tip at a distal end of the wire. The coupling is arranged to couple the source to the wire at any one of a plurality of discrete operating positions along the length of the wire for the transmission of ultrasonic energy to the active tip.)

1. An intravascular device for traversing an obstruction in a blood vessel, the device comprising:

an elongated intravascular wire; and

a coupling for transmitting, in use, ultrasonic energy along the wire from the source of ultrasonic energy to an active tip at a distal end of the wire;

wherein the coupling is arranged to couple the source to the wire at any one of a plurality of discrete operating positions along the length of the wire for the transmission of ultrasonic energy to the active tip.

2. The apparatus of claim 1 wherein the coupling is arranged to effect relative longitudinal movement between the source and the wire when moving between the operative positions.

3. The apparatus of claim 2, wherein the coupling is arranged to effect the relative longitudinal movement while remaining attached to the wire.

4. The apparatus of claim 2 wherein the coupling is arranged to effect the relative longitudinal movement by removal from and reattachment to the wire.

5. The apparatus of claim 4, wherein the coupling and/or the source comprise distal and proximal or lateral openings for longitudinal insertion and withdrawal of the wire.

6. The apparatus of claim 4, wherein the coupling and/or the source comprises at least one longitudinal slot for the wire to enter or exit in a lateral direction transverse to a longitudinal axis of the wire.

7. The apparatus of claim 6, further comprising a locking mechanism arranged to capture the wire after it enters laterally through the slot and release the wire to exit laterally through the slot.

8. The apparatus of claim 7, wherein the locking mechanism comprises at least one locking member rotatable about the wire to capture and release the wire.

9. Apparatus according to any preceding claim, wherein the coupling is arranged to clamp the wire when in any of the operative positions.

10. The apparatus of claim 9, wherein the coupling comprises a collet radially compressible onto the wire in response to longitudinal movement or longitudinal compression of the collet.

11. The apparatus of claim 10, wherein the collet includes at least one mating face that engages the source, the face being inclined relative to a longitudinal axis of the collet.

12. The apparatus of claim 11, wherein the mating surface is defined by a tapered end of the collet.

13. The apparatus of claim 11 or claim 12, wherein the collet is movable longitudinally within or relative to a transducer used as the source.

14. The apparatus of claim 13, comprising threads between the collet and the transducer, the threads arranged to move the collet longitudinally and couple the collet to the transducer.

15. The apparatus of any preceding claim, wherein the wire extends through the source and has portions extending proximally and distally from the source, respectively.

16. The apparatus of claim 15, wherein the proximally extending portion of the wire exits a proximal end of the source.

17. The apparatus of claim 15, wherein the proximally extending portion of the wire exits the source on an axis transverse to a longitudinal axis of the distally extending portion of the wire.

18. The apparatus of any preceding claim, wherein the operating position is marked on the wire.

19. The apparatus of any preceding claim, wherein the operating position is a characteristic of a harmonic of the wire at an activation frequency of the source.

20. An intravascular device for traversing an obstruction in a blood vessel, the device comprising:

an electrically driven ultrasonic energy source;

a coupling for exciting, in use, an intravascular wire to transmit ultrasonic energy along the wire from the source thus coupled to the wire to an active tip at a distal end of the wire; and

a signal acquisition and processing system configured to capture and respond to operating parameters of the device as the active tip approaches or passes through an obstruction in use.

21. The device of claim 20, wherein the signal acquisition and processing system is configured to monitor changes in frequency and/or amplitude of a current drawn by the source of ultrasound energy or a voltage dropped across the source of ultrasound energy.

22. The apparatus according to claim 20 or claim 21, wherein the signal acquisition and processing system is configured to modulate an excitation voltage applied to the ultrasound energy source or an excitation current supplied to the ultrasound energy source.

23. The device of claim 22, wherein the signal acquisition and processing system is configured to control the ultrasound energy source by varying a frequency and/or amplitude of the excitation voltage applied to the ultrasound energy source.

24. The apparatus of claim 23, wherein the signal acquisition and processing system is configured to drive the frequency of the excitation voltage by employing a phase difference between the excitation voltage and the excitation current in combination with an amplitude of the excitation voltage.

25. The apparatus of any of claims 20-24, wherein the signal acquisition and processing system is configured to monitor changes in the vibration frequency or amplitude of the wire via the coupling.

26. The apparatus of claim 25, wherein the signal acquisition and processing system comprises an amplitude feedback controller and is configured to use a resonant frequency as an operating point for control.

27. The apparatus of claim 25 or claim 26, wherein the signal acquisition and processing system is configured to infer displacement of the active tip of the wire from a waveform in the wire determined from the change in vibration frequency of the wire.

28. The apparatus of claim 27, wherein the signal acquisition and processing system is configured to employ a numerical algorithm selected for a particular type of the wire.

29. The device of claim 27 or claim 28, wherein the signal acquisition and processing system is configured to estimate an area of gelatinous, fibrous, and calcified lesions delineated by the displacement of the active tip of the wire in open and occluded vasculature.

30. The apparatus according to any one of claims 20 to 29, wherein the signal acquisition and processing system is configured to monitor proximity to an obstruction and/or determine a characteristic of an obstruction from the captured operating parameters.

31. The device of any one of claims 20 to 30, wherein the signal acquisition and processing system is configured to compare the relative contribution of losses from anatomical tortuosity as the active tip is navigated to the obstruction to losses due to the active tip passing through the obstruction.

32. The device of claim 31, wherein the signal acquisition and processing system is configured to pulse or vary a drive signal to the ultrasound energy source.

33. The device of any one of claims 20-32, wherein the signal acquisition and processing system is configured to run an intravascular wire type specific algorithm to estimate deflection of the active tip when energized, and to estimate a tunnel diameter extending through the obstruction.

34. The apparatus of any of claims 20 to 33, wherein the signal acquisition and processing system is configured to:

monitoring modulation of a transmission signal and automatically controlling a voltage applied to the ultrasonic energy source to compensate for background energy losses encountered in the wire when the active tip is proximate the obstruction; and

distinguishing the background energy loss from an additional energy loss of the active tip when passing through the obstruction and compensating for the background energy loss to maintain a displacement at the active tip.

35. The apparatus of any one of claims 20 to 34, further comprising a manual override device operable to modulate the power output of the ultrasonic energy source.

36. The apparatus according to any one of claims 20 to 35, wherein the signal acquisition and processing system is configured to compare the captured operating parameters with stored data characterizing known obstructions, and to characterize the obstruction with reference to the comparison.

37. The apparatus of any one of claims 20 to 36, wherein the signal acquisition and processing system further comprises an output to a user interface and/or to an external data acquisition system.

38. The apparatus of any one of claims 20 to 37, wherein the signal acquisition and processing system further comprises an input from a user interface and/or from an external data network.

39. The device according to any one of claims 20 to 38, wherein the signal acquisition and processing system is configured to modify or change a control algorithm in response to a change in the operating parameter of the device, the change being caused by interaction of the active tip with an obstruction in use.

40. The apparatus of any one of claims 20 to 39, wherein the signal acquisition and processing system is configured to output data to an external data network and in response receive data from the network, and to modify or change the control algorithm accordingly as data is received from the network.

41. The device of claim 40, wherein the signal acquisition and processing system is configured to output data to the network representative of a change in the operating parameter of the device, the change resulting from interaction of the active tip with an obstruction, in use.

42. The apparatus of any preceding claim, wherein the source comprises a transducer that vibrates at a frequency between 20kHz and 60 kHz.

43. The apparatus of claim 42, wherein the transducer vibrates at a frequency between 35kHz and 45 kHz.

44. The apparatus of claim 43, wherein the transducer vibrates at a frequency between 37kHz and 43 kHz.

45. The apparatus of claim 44, wherein the transducer vibrates at a frequency substantially equal to 40 kHz.

46. The apparatus of any preceding claim, further comprising a subsequent intravascular diagnostic or therapeutic device deliverable distally along the wire into the vasculature of a patient after separation of the source from the wire.

47. A communication system comprising a device according to any preceding claim in data communication with a computer system arranged to receive data from the device, to optimise and update a control algorithm accordingly, and to output the optimised, updated control algorithm to the device.

48. A communication system as claimed in claim 47, wherein two or more such devices are in data communication with the computer system, the computer system being arranged to optimise a control algorithm in accordance with data received from a plurality of procedures performed using the devices and to output the optimised, updated control algorithm to the devices.

49. An elongate intravascular wire for passing through an obstruction in a blood vessel, the wire comprising a coupling for transmitting, in use, ultrasonic energy along the wire from a source of the ultrasonic energy to an active tip at a distal end of the wire, wherein the coupling is arranged to couple the source to the wire at any one of a plurality of discrete operating positions along the length of the wire for the transmission of ultrasonic energy to the active tip.

50. An elongate intravascular wire for passing through an obstruction in a blood vessel, the wire comprising:

a coupling for transmitting, in use, ultrasonic energy along the wire from the source of ultrasonic energy to an active tip at a distal end of the wire; and

a cutting device on the link or on the wire to cut through or score the wire to sever the link from a portion of the wire that extends distally from the cutting device.

51. The wire of claim 50, wherein the cutting device comprises at least one blade movable laterally relative to a longitudinal axis of the wire.

52. An elongate intravascular wire for passing through an obstruction in a blood vessel, the wire comprising:

a coupling for transmitting, in use, ultrasonic energy along the wire from the source of ultrasonic energy to an active tip at a distal end of the wire;

wherein the coupling comprises: a screw connector secured to a proximal end of the wire; and a rotating sleeve engaged with the screw connector in a first longitudinal position to rotate the screw connector into engagement with the source of ultrasonic energy, and then movable to a second longitudinal position to separate the sleeve from the screw connector and the wire.

53. The wire of claim 52, wherein the first longitudinal position is disposed proximally relative to the second longitudinal position.

54. An elongate intravascular wire for passing through an obstruction in a blood vessel, the wire comprising a proximal segment; a distal tip section having a smaller diameter than the proximal section; and a distally tapered intermediate section extending between the proximal section and the distal tip section, wherein the wire is substantially sleeve-free over its entire length.

55. The wire of claim 54, comprising at least one weld joint between at least two of the segments.

56. The wire of claim 54 or claim 55, wherein the distal tip segment comprises a bulbous distal tip.

57. The wire of any one of claims 54 to 56, wherein the distal tip section comprises a distal portion that is angularly offset relative to a longitudinal axis of the wire.

58. The wire of any one of claims 54-57, wherein a marker band encircles at least the distal tip segment.

59. The wire of any one of claims 54-58, having an overall length of between 500mm and 2500 mm.

60. The wire of any one of claims 54-59, wherein the proximal segment has a uniform diameter along its length.

61. The wire of claim 60, wherein the proximal segment has a diameter of 0.014 to 0.035 inches (about 0.36 to about 0.89 mm).

62. The wire of any one of claims 54-61, wherein the proximal segment of the wire has a length of 500mm to 2000 mm.

63. The wire of any one of claims 54-62, wherein the length of each of the segments is a function or multiple of λ/4, where λ is the drive frequency that causes resonance in the wire.

64. The wire of any one of claims 54-63, wherein the distal section is tapered or has a constant diameter along its length.

65. The wire of claim 64, wherein the distal segment has a diameter of 0.003 to 0.014 inches (about 0.08 to about 0.36 mm).

66. An intravascular device comprising the wire of any one of claims 49-65 and an ultrasound energy source coupled to the wire.

67. An activation unit for delivering ultrasound energy into an elongate intravascular wire, the unit comprising:

a source of said ultrasonic energy; and

a coupling arranged to couple the source to the wire at any one of a plurality of discrete operating positions along the length of the wire.

68. A unit as claimed in claim 67 wherein the linkage is arranged to effect relative longitudinal movement between the source and the wire when moving between the operative positions.

69. The unit of claim 68 wherein the coupling is arranged to effect the relative longitudinal movement while remaining attached to the wire.

70. The unit of claim 68 wherein the coupling is arranged to effect the relative longitudinal movement by removal from and reattachment to the wire.

71. A unit as claimed in any of claims 67 to 70, in which the source comprises a transducer which vibrates at a frequency of between 20kHz and 60 kHz.

72. A unit as claimed in claim 71, in which the transducer vibrates at a frequency of between 35kHz and 45 kHz.

73. A unit as claimed in claim 72, in which the transducer vibrates at a frequency of between 37kHz and 43 kHz.

74. A unit as claimed in claim 73, wherein the transducer vibrates at a frequency of between or substantially equal to 40 kHz.

75. The unit of any one of claims 67 to 74, further comprising a visual, tactile and/or audio user interface.

76. A method of reducing obstructions in a channel, the method comprising:

coupling a source of ultrasonic energy to an elongate wire at any one of a plurality of discrete operating positions along the length of the wire; and

transmitting ultrasonic vibrations from the source along the wire to vibrate an active tip at a distal end of the wire in contact with the obstruction.

77. The method of claim 76 including effecting relative longitudinal movement between the source and the wire when moving between the operative positions.

78. The method of claim 77, comprising effecting said relative longitudinal movement while said source remains attached to said wire.

79. The method of claim 78, comprising moving the wire longitudinally while holding the source substantially stationary.

80. The method of claim 77, comprising effecting said relative longitudinal movement by removing said source from said wire and reattaching said source to said wire at a different longitudinal position.

81. The method of claim 80, comprising moving the source longitudinally while holding the wire substantially stationary.

82. The method of claim 80 or claim 81, comprising removing the source from or attaching the source to the wire by relative movement between the source and the wire in a lateral direction transverse to a longitudinal axis of the wire.

83. The method of any one of claims 76 to 82, comprising clamping the wire when the source is in any one of the operating positions.

84. A method of reducing obstructions in a channel, the method comprising:

transmitting ultrasonic vibrations along an elongate wire from an ultrasonic energy source to vibrate an active tip at a distal end of the wire in contact with the obstruction; and

delivering a subsequent diagnostic or therapeutic device distally along the wire.

85. The method of claim 84, comprising removing the source from the wire prior to delivering the subsequent device along the wire.

86. A method of reducing obstructions in a channel, the method comprising:

transmitting ultrasonic vibrations along a wire from an electrical drive source coupled with the wire to vibrate an active tip at a distal end of the wire in contact with the obstruction; and

sensing a response of the vibrating wire to interaction with the obstruction as the active tip encounters and passes through the obstruction.

87. The method of claim 86, further comprising comparing sensed data representative of the response of the vibrating wire to stored data representative of a response of a corresponding vibrating wire to interaction with a known obstruction.

88. The method of claim 86 or claim 87, further comprising adjusting an amplitude or frequency of the ultrasonic vibrations transmitted along the wire to the active tip in response to sensing the response of the vibrating wire.

89. The method of any one of claims 86 to 88, comprising sensing the amplitude of vibration of the wire and controlling the source to maintain a resonant frequency in the wire.

90. The method of any one of claims 86 to 89, comprising modifying or changing a control algorithm in response to a change in the response of the vibrating wire.

91. The method of any one of claims 86 to 90, comprising: outputting the data to an external data network; receiving data from the network in response; and modifying or changing the control algorithm accordingly upon receiving data from the network.

92. The method of claim 91, comprising: outputting data representing a change in the response of the vibrating wire to the network.

93. The method of any one of claims 86 to 92, comprising: outputting the data to an external computer system; optimizing and updating, in the external computer system, a control algorithm based on the data; outputting the optimized, updated control algorithm from the external computer system; and controlling the vibration of the wire using the optimized, updated control algorithm.

94. The method of claim 93, wherein the computer system optimizes the control algorithm based on data received from a plurality of protocols.

95. A method of characterizing an obstruction in a blood vessel, the method comprising comparing measurement data representing a response of a previously delivered vibrating intravascular wire to interaction with the obstruction to stored data representing a response of a corresponding vibrating intravascular wire to interaction with a known obstruction.

96. The method of claim 95, comprising adjusting vibration of the pre-delivered intravascular wire in response to the comparison between the measured data and the stored data.

97. The method of claim 95 or claim 96, comprising the preliminary steps of: an algorithm for selecting a particular type of intravascular wire and selecting a wire specific to the type of intravascular wire for determining a response of the selected wire to an obstruction.

Technical Field

A broad approach to using ultrasonic vibrations transmitted through small diameter catheters and components has been established in the outdated and recent prior art, as exemplified by US 3433226. US 5971949 describes the transmission of ultrasonic energy via waveguides of different configurations and tip geometries. US 5427118 describes an ultrasonic guidewire system but does not discuss in detail the proximal geometry of the wire or how it facilitates subsequent devices via a through-wire approach.

Many current single transducer systems are not ultrasonically activated guidewires, but are ultrasonically activated catheters that contain a wire member to agitate and ablate the substance. US 6855123 and US 4979939 describe such systems. These catheters themselves require a separate passive guidewire to assist them in navigation and, therefore, are tools to facilitate passage of the separate guidewire through the occlusion. US 9629643 shows a system having a series of distal tip configurations, but all requiring a separate guidewire for access.

These devices are intended to deliver an alternative method of revascularization and are described as atherectomy devices. They were not found to facilitate delivery of the device across lesions to achieve revascularization by conventional PTA and PTCA treatment devices.

These ultrasound devices and recanalization devices are associated in the art with the claims that they enhance clinical atherectomy procedures. They enhance revascularization and provide or effect atherectomy procedures by removing plaque that forms the lesion to reduce the volume of the lesion.

Many prior art disclosures suggest a reduced likelihood of vessel dissection as a result of the atraumatic manipulation of such devices against soft compliant tissue. Some facilitate movement of the wire through the vasculature without relying on hydrophobic or hydrophilic coatings.

There is also repeated mention in the art of how the vibration of an ultrasound intravascular device can reduce the likelihood of vasospasm, an adverse event that can occur during any angioplasty procedure using conventional devices. This therapeutic benefit is believed to result from the vibrating effect of the wire massaging the tissue, see US 5324255.

Early researchers of these revascularization devices reported in the open literature how their efficacy was affected by contact with tissue, and they explained how these revascularization devices increased power in the system to overcome losses by manually adjusting the voltage to overcome the losses in a stepwise increasing manner. This illustrates the need to provide some means of overcoming the effects of losses, such as changing the voltage to increase the amplitude or changing the frequency.

In later and current designs, the ultrasonic generator system has become a large unit, scaled to generate and control the pulse wave. While today's electronics make it possible to package such systems in smaller form, the cost of miniaturization is not to this end. In addition, practical considerations mean that known systems typically include separate elements. For example, many systems are designed with the signal generator housed in a unit separate from the transducer, some mounted on large cart units that occupy significant space in the clinical environment. US 6450975, US 2008/0228111 and US 9282984 all describe such systems.

In the prior art, many systems describe semi-automatic control of amplitude by monitoring the current through a feedback loop. This provides a way to achieve maximum tip displacement through the device's passage through the vasculature and tunneling through the lesion by modulating the voltage. These systems do not directly relate this modulation to tip displacement and tunneling effects or to the composition or characteristics of the lesion.

US 6577042 to Angiosonic describes the modulation of output amplitude by current in an algorithm that interrogates the transducer current over a small range of frequencies. This maintains the power at a constant level and also monitors the current and voltage over a small range of frequencies to detect failure of the sonotrode (sonotrode), the active member, and to confirm the optimized output frequency.

WO 2018/002887 to soudbite describes a different approach in which multiple transducers or wave foci are used to generate a concentrated waveform. This again results in the need for a large physical unit. The unit constructs an output ultrasonic wave by coordinating the acoustic waves generated by the transducers in the device by taking at least two different component waves and combining them in a waveguide to form the desired output wave. All of these methods require extensive data acquisition and computer systems to implement the solution.

The method of coupling the mechanical waveguide or transmission member to the horn is critical and a number of connection methods are disclosed. US 4572184 discloses a method of using a screw connector, wherein a wire is held in a screw. In addition to internal connection mechanisms, there are many patents associated with design features to allow a user to interact with these mechanisms, such as US 6508781, US 5971949, US 5417672, and US 9433433.

Constraints in the lateral direction have also been proposed to optimize the way the wire will migrate through the vessel. The document also proposes providing strain relief at the transfer joint.

While there are also proposals for hollow constructions as in US 4538622, the properties of the wire have been suggested in relation to its form or shape, with solid wires such as disclosed in US 6589253 being the most common. It is proposed to modify the wire by tapering to drive the distal tip displacement and to optimize the resonance along the length of the wire. The composition of the material is also critical in terms of type and combination and composite construction, as disclosed for example in US 8500658 and US 5397301, respectively.

Ultrasound-activated catheter and wire systems have been considered in the past as methods of atherectomy and preparation of blood vessels for angioplasty treatment. Some products were commercially available in the past, some products were still available on the market, and some new systems have recently been marketed. These various types of catheters are mentioned below.

These catheter and wire systems typically include a) an ultrasonic generator that converts mains electrical power into an ultrasonic waveform defined by its voltage amplitude and frequency; b) an ultrasonic transducer, and typically an amplifying horn, which converts electrical energy into high frequency mechanical vibrations defined by a vibration frequency and amplitude; and c) a small diameter waveguide coupled to the horn, the small diameter waveguide transmitting the mechanical vibration to the distal tip of the wire. This causes the distal tip of the wire to vibrate at a desired amplitude and frequency in order to ablate the material and ultimately facilitate revascularization or recanalization of the systemic vessel and anatomy.

Tissue and material near the distal tip are affected by a combination of ultrasonic movement of the tip and its direct mechanical wear, ablation, and cavitation from the pressure wave component and acoustic streaming that removes ablated material from the area around the tip.

Background

Ischemia is a deficiency in the blood supply to a body organ. In atherosclerotic vessels, ischemia occurs as a result of the vessel being occluded by an obstruction caused by a lesion in the vessel wall, atherosclerotic plaque, or emboli produced by other sources. Atherosclerotic plaques are composed of a substance whose structure becomes increasingly rigid over time.

By partially or completely occluding the vessel, the occlusion restricts blood flow to the tissue distal to the occlusion, resulting in cell death and rapid deterioration of tissue health.

A preferred mode of treatment for such blockages is minimally invasive intravascular angioplasty. In these procedures, small diameter therapeutic devices are introduced into the vasculature and navigated to the obstruction via the lumens of the veins and arteries, and deployed at the site of the lesion to restore patency. These procedures which reestablish occluded blood flow in the coronary and peripheral arteries in the treatment of chronic atherosclerotic plaques may also be used to treat acute embolic occlusions, thrombi, or occlusive blood clots.

The anatomical structures that perform these procedures include, but are not limited to, coronary arteries, neuro-vascular and peripheral arteries that serve the lower extremities. Different anatomical structures are associated with different lesions. Lesions found in various peripheral vessels pose different types of challenges to lesions found in coronary arteries. The iliac, femoral, popliteal, and popliteal arteries have different tortuosity, and are typically significantly smaller than the coronary or neural vasculature. However, these arteries are prone to extensive calcification, which is a serious impediment to successful endovascular procedures.

In intravascular procedures, arteries are selected and recruited for gaining access to the vasculature. The ability to adapt the pathway of the intended diagnostic or therapeutic device to the target site based on the artery is selected and the extent to which it can minimize tissue and patient trauma.

In peripheral arterial revascularization procedures, the femoral, popliteal and plantar arteries are typically accessed through surgical incisions and punctures, which is commonly referred to in medical terminology as the Seldinger technique. Once inside, the guidewire and introducer sheath are inserted into the vessel and secured at the site. The sheath serves as a port for introduction, withdrawal and replacement of the device and minimizes abrasion of the arterial tissue. A guide catheter and guidewire are then introduced into the artery to provide further protection and to assist in navigation of the device to the target site.

The guidewire is carefully pushed along the vessel lumen to avoid any trauma to the vessel wall and to navigate the guidewire to the obstruction site. In a successful procedure, a guidewire is then pushed across or through the obstruction and held in place to act as a guide through which diagnostic or therapeutic devices (such as balloon catheters and stents) are tracked to the site of the occlusion. Guidewires are used for other minimally invasive procedures to introduce other devices and instruments into a blood vessel or other lumen of the body to enable inspection, diagnosis, and different types of treatment.

In the case of balloon angioplasty, after a balloon catheter is introduced into the vessel over a guidewire and navigated to the site of the occlusion, the balloon is then expanded, thereby destroying or compressing the occluding material and restoring blood flow. Sometimes, a stent is placed over the crushed diseased area to act as a support frame for maintaining vessel patency.

Visualization of the progress of guidewires and other diagnostic treatment devices being advanced through the anatomy is typically accomplished by X-ray or duplex ultrasound. MRI is becoming more common in other anatomical structures.

Other medical procedures using the above-mentioned guidewires include gastrointestinal, urinary and gynecological procedures, all of which require the formation of a passageway through an occlusion in order for a larger and often more cumbersome device to pass to a lesion or other target tissue distal to the lesion in the body.

Guidewires are critical for therapeutic intervention and are made of different materials, most typically stainless steel and NiTi (nitinol), with many different designs. Their manufacture involves altering the microstructure morphology of the material, such as by cold working the material while forming it into a wire, and then working the wire into different dimensional designs to achieve the desired properties. As one example, a particular taper may be machined into the length of the wire to create a differential degree of flexibility along the length of the wire. Thus, the wire will have sufficient flexibility at its distal end to conform to the shape of the vessel, and have a strength to transmit force to the tip ("tip strength") or through the lesion.

The construction of these devices typically includes a thin coil that may extend the entire length of the wire or discrete segments, most typically the distal segment. These coils help to transfer forces over the tapered section and increase the forces that can be transferred through the entire length of the wire. They also allow the wire to easily conform to the shape of the vessel and track through tortuous anatomy that may be encountered particularly in coronary and neurovascular anatomy.

The wires are made available within a range of outer diameters associated with the anatomy they are treating. Wires having a diameter of about 0.010 inches (about 0.25mm) are typically used in neurovasculature, while wires having an outer diameter of 0.014 to 0.018 inches (about 0.36 to about 0.46mm) are typically used in coronary applications. These 0.014 inch and 0.018 inch (about 0.36mm and about 0.46mm) wires are also used in many peripheral vasculature, typically for the popliteal infrapodal and tibial anatomy. In accessing and treating diseased larger diameter and straighter vessels, such as iliac, aortic, and thoracic vessels, wires having a typical outer diameter of 0.035 inches (about 0.89mm) can be used. Wires with outer diameters of 0.016 inches (about 0.4mm) and 0.018 inches (about 0.46mm) are common in accessing femoral, popliteal and infrapopliteal vessels.

The length of the wire used in intravascular procedures also varies depending on the distance they are deemed likely to operate. As one example, wires, typically 750mm up to 900mm in length, are used in many peripheral applications where they may be introduced into the femoral or popliteal anatomy, or require tracking to and through occlusions in the ipsilateral iliac femoral and infrapopliteal arteries. The length of wires used in contralateral and coronary applications is often about 1200mm, 1500mm or 1700 mm. In practice, the wire that can be traced contralaterally may be longer, perhaps about 2000mm to 2250mm or 2500mm in length.

These conventional intravascular wires are passive in that they do not transmit any energy other than that applied by the clinician. They are of different construction and design to facilitate access to and passage through lesions in different anatomical structures, and are used with different devices. However, in many cases, occlusions are too challenging for conventional wires to pass through.

In the case of peripheral arteries, these blockages are often too severely diseased and consist of too recalcitrant substances to allow the passage of the wire, and in these cases, intravascular planning takes significantly more time to progress, or often requires more devices to pass through the lesion or the lesion is only abandoned many times.

In more than 50% of cases of peripheral arteries, particularly in the popliteal, tibial and peroneal arteries, the vessels are completely occluded by the lesion; in about 30% of cases, the target lesion is heavily calcified. These calcified lesions actually consist of rigid inelastic segments that typically extend to lengths of 3cm to 5cm within widely diffuse lesions of even longer average length of about 20 cm. The choice of treatment for these lesions requires knowledge of their length and composition, which is not readily available from conventional imaging.

If the guidewire is unable to pass through a lesion in a blood vessel, the possible success of the procedure is significantly affected. The failure of the guidewire to pass through lesions in the vessel prevents preferred follow-up procedures, such as balloon angioplasty and stent implantation, and limits the ability to treat the patient.

Occlusion in the distal popliteal inferior blood vessel or the anterior, posterior and peroneal arteries leads to ischemic responses to wounds and trauma, resulting in refractory ulceration of wounds and incisions and other damage to tissue. This anticipated response makes surgical intervention less attractive, promoting the need for intravascular solutions to Chronic Total Occlusion (CTO).

The inability of conventional wire designs to generally pass through refractory lesions has led to the development of advanced minimally invasive endovascular surgical techniques in the last two decades, which employ conventional guidewires and balloons. These procedures are technically challenging, requiring a great deal of skill and training and specialized equipment created to enable them to be completed more efficiently. Techniques such as subintimal and retrograde approaches have been developed and reentry devices have emerged to assist in this procedure.

The subintimal technique bypasses the lesion by creating a new pathway by tunneling along the intima of the vessel, around the media over the length of the lesion, and re-enters the vessel distally. These pathways are established by balloon dilation and stenting to maintain patency. Reentry devices have been developed to facilitate these procedures.

Retrograde techniques utilize a softer distal cap of the occlusion, which is easier to pass through than calcified proximal caps encountered in antegrade (femoral) approaches. In these retrograde techniques, access is obtained through blood vessels distal to the lesion of the foot or ankle in the case of peripheral disease; or access is gained through collateral (usually septal) vessels in the coronary anatomy. These procedures are more complex; they require more skill and take longer to complete.

In the peripheral sub-iliac procedure, time is spent trying the conventional (antegrade) approach and in further antegrade attempts escalating by wire, then escalating to the retrograde approach to cross the lesion.

In resource-limited healthcare systems, the increasing demand makes the adoption of these life-saving and limb-preserving endovascular techniques problematic for the clinical community. They arguably provide optimal patient outcomes, consume less hospital and community care resources, and provide better financial results for healthcare systems. However, widespread awareness of these results, limited hospital and clinical resources, and the significant level of clinical training and practice required by current technology, have limited adoption.

Conventional intravascular guidewires are passive mechanical devices with no active components. They operate by their proximal ends being pushed, pulled and twisted to navigate to the site of the obstruction, and then pushed through or around the obstruction. Their design balances surface properties, stiffness, and flexibility to optimize the way they navigate and function when delivering therapy. These passive wires do not work as expected from guidewires or are limited when attempting to pass through near-or total-occlusion obstructions, which may also be significantly calcified.

Disclosure of Invention

The present invention is a subversive advance over conventional intravascular guidewire designs, as well as existing activated guidewire and catheter systems, in which mechanical vibrations are transmitted to the distal tip via a wire.

Aspects of the inventive concept are expressed in the appended claims.

An ultrasound system is disclosed that induces vibrations in a customized endovascular surgical wire device, interrogates and applies artificial intelligence and/or intelligent electronics to feedback in the system for optimizing the performance of the device in navigating to and through endovascular occlusions and characterizing endovascular occlusions.

The present invention provides a device that aims to rapidly penetrate and traverse any occlusion of any component in any artery or other vessel. The device may be used in stand-alone procedures to achieve revascularization and restore blood flow in foot applications or other situations. However, the device is most advantageously used to facilitate the subsequent delivery of intravascular diagnostic and therapeutic devices to effect and assist in revascularization of blood vessels.

The goals of ultrasound active guidewire devices are 1) to pass through complex and calcified vascular occlusions, either as a stand-alone procedure, or as an active or passive guidewire, and 2) to provide a catheter to enable the passage of auxiliary devices to achieve revascularization and stenting of the vessel.

The concept of a wire or ultrasound activation system locates and clamps the proximal end of the device in the literature, in patents, and in products entering the market.

Embodiments of the invention provide for the transmission or activation to be performed at intervals anywhere along the length of the wire. This allows the activation device to be moved along the length of the wire or left at a particular location, such as near the activation port, and the wire moved into and out of the device in preparation for passing through the treatment device.

In a sense, the invention resides in a system comprising three interconnected components, namely: a) compact housings and components for ultrasound sources and connectors; b) an active crossing wire assembly for entering the anatomical system and transmitting energy to the active distal tip; and c) a signal acquisition, processing and communication chipset. The compact housing unit has an ultrasound generator; an ultrasound transducer, a horn and a control unit collectively housed in a portable compact housing unit designed to be connected by a coupling unit that energizes the intravascular crossing wire and monitors and modulates the energization of the system in order to effect crossing and characterization of the intravascular occlusion. An on-board signal acquisition and processing chipset may acquire and control the excitation of the signal generator and provide communication from the system to its user and/or the output of an external data acquisition system.

The present invention resides in a device that advantageously ultrasonically activates an endovascular crossing wire along its entire length. Upon separation from the activation unit via the detachment device of the present invention, the crossing wire has a nominal outer diameter that may enable the wire to function as a primary crossing device. The activation units may be coupled to and separated from the wire and coupled at intervals along the length of the wire. When detached, the activation unit also facilitates passage of treatment devices, such as atherectomy vessel preparation devices, angioplasty catheters, and stents, through the wire to the site of the occlusion.

The controller may monitor the frequency and amplitude of the current and voltage and the measurements of the frequency and amplitude of the incident, reflected and standing wave waveforms, and may estimate the distal tip displacement therefrom. Modulation of these variables can be monitored as the wire passes through the anatomy and through different types of occlusions, including calcified chronic total occlusions. Determining the duration or length of calcified and non-calcified lesions and calcified segments is key to some aspects of the invention.

The signal used to drive the ultrasonic generator can be pulsed or varied to reduce heating and optimize analysis and matching of shifts at the resonant frequency. Pulsing of the voltage over a small frequency range can activate the traversing wire. The digital signal processor unit may interrogate the measurements made, provide feedback and interpret and compare the relative contribution of losses due to anatomical tortuosity to losses due to crossing occlusions when navigating to the site.

For each standard wire type, a specific algorithm may be employed to estimate the diameter described by the deflection of the distal tip when excited at different levels of frequency and power and device configuration under conditions relevant to the procedure. The algorithm may estimate a diameter along the length of the tunneling segment through the occlusion.

The system of the present invention can process data obtained from measurements indicative of the ultrasound waveform as it passes through the vasculature and through the occlusion as it is generated, as it passes through the transmission member, and as the transformation of the resonant vibration occurs, as the reflected waveform is attenuated by the transmission member. The data is processed or manipulated by onboard algorithms to perform operations that convert the raw data into procedure related outputs.

In the case of monitoring and analyzing the modulation of the transmitted signal, the system of the present invention can adjust the energy loss in the system through voltage control, possibly automatically, to increase the power in the system and compensate for the energy loss encountered in the wire as it passes through the vasculature to an occlusion. The system can distinguish these losses from the additional losses as the wire passes through the occlusion, and can compensate for the latter losses to maintain displacement at the distal tip.

The measured parameters and variables may be numerically operated to determine the rate of change of these measurements relative to each other and other parameters. The system of the invention can numerically compare and interpret the difference between these calculated values from the active system and a set of prescribed values in order to characterize the nature of the substance occluding the blood vessel. Optionally, the energy may be manually controlled by an override controller that enables a user to increase the power in the system, and thus increase the energy level driving the waveguide. Methods of providing manual pulse override by adjusting current or voltage can be used to immediately or pre-address sudden losses in the system due to accidents or interference with the wire.

The output may be presented visually on a small display or via tactile or audio hardware (such as a tactile interface) located on a device accessible and visible to the user.

Optionally, the active crossing wire assembly may be used in a passive mode without ultrasonic activation, or the wire may be mechanically coupled to an ultrasonic transducer and acoustic horn in the housing unit to transmit ultrasonic vibrations, and then the wire may be detached from the housing unit to return it to a configuration for a subsequent procedure.

The active wire assembly may be connected by means for connecting the active wire assembly to the acoustic horn and the compact housing unit in a manner that allows efficient transmission of ultrasonic vibrations to the wire assembly. The geometric proximal tip can be optimized for easy positioning, loading, and interference fit into a coupling connector to facilitate rapid loading and unloading and accurate and reliable transfer of energy through the wire.

The proximal end of the wire may be shaped to allow it to be positioned into and engaged in direct contact with the acoustic horn. Once the wire is in this position, the secondary mechanism may be clamped or locked into position in cooperation with the circumferential surface of the locking unit, whereupon the wire remains in place until the mechanism is released.

Customized active crossing wire assemblies can be provided to systems with integrated positioning bosses that allow components to be positioned in or out of the coupling for a procedure. A device may be provided for rapid separation of an ultrasonically activated intravascular wire from an acoustic horn by a mechanism that cuts the wire in a precisely controlled manner to allow the remainder of the device to be used as a delivery wire for subsequent procedures. The boss may perform the function of either or both of the joining and cutting or breaking of the wire.

The custom active wire assembly may have features that optimize radiopacity under high frequency deflection, placed at regular intervals along the length of the assembly, and visible under duplex imaging. Such features may be machined and/or may include marker bands of, for example, gold or platinum. Ultrasound as well as X-rays can be used to estimate the occlusion length during the procedure.

The distal tip edge of the crossing wire may be rounded and polished to limit the possibility of trauma to the tissue, and may be made of scratch resistant material optimized to pass through lesions.

The customized crossing wire of the present invention may have a shapeable or shapeable distal tip for manipulation and radiopacity for visibility to provide more effective tracking to and through the target lesion and to facilitate access to the side branch.

The crossing wires are made of a resilient fracture-resistant material, such as ASTM type I to type IV low inclusion density nitinol wires, selected based on the optimized characteristics of the different diameters and the targeted anatomy.

The crossing wire may have lubricious hydrophilic and hydrophobic coatings and/or low friction sheaths to further minimize the adverse effects of micromotion and minimize the possibility of coagulation.

The controller may process all measurements of the converted transmit and receive waveforms. The user interface may convey tracking performance and progress as one progresses through any obstruction and provide feedback via visual, audio, or haptic means (such as haptics) regarding characterization of the composition and length of the lesion.

The system of the present invention may enable data transfer between a device and another device or a wireless or cloud service for analysis and storage.

An accessory device attached to a luer device through which the wire passes may provide telemetry related to the movement of the wire through the vessel.

Automated drivers may be used to carefully control the rate of insertion and withdrawal of the wire into the vasculature to provide more accurate feedback on the composition of plaque passing through the length of the lesion. This provides a means to achieve more complex characterization of the lesion and the intravascular environment.

The acoustic horn and transducer assembly may have a hollow port through the full length of the assembly with an internal wire connect/disconnect mechanism or locking collet.

The system of the present invention may include three interconnected components, with the components of the ultrasound system being broken down. For example, the generator may be separate from the compact unit.

The wire may be secured in a crimp sleeve that captures the wire over the length of the sleeve. The sleeve may be cylindrical or may preferably have a polygonal cross-section, such as a hexagonal or octagonal pattern, which collapses onto the wire in a uniform manner. The sleeve or other coupling structure such as a collet may be made of stainless steel or aluminum, for example.

The crimped section may be applied under controlled force and the wall thickness of the collapsed sleeve ensures that a uniform load is applied to the wire. Conveniently, the proximal end of the crimp sleeve may be threaded to screw into the transducer head. Alternatively, the wire may be secured in a crimped set screw that captures the wire at the proximal length.

Structure of the device

In a preferred embodiment, the system of the present invention comprises:

a) a signal power generator;

b) an ultrasonic transducer;

c) optionally an acoustic horn;

d) a transmission waveguide or crossing wire that can transmit high frequency ultrasonic vibrations from a proximal end to a distal tip thereof for ablation by a non-compliant substance occluding an artery and having dimensions that facilitate standard diagnostic and therapeutic devices;

e) a link, which is an attachment mechanism that couples the transmission wire to the acoustic horn or directly to the transducer, that minimizes losses and enables accurate and reliable transmission of high frequency mechanical vibrations;

f) means for detaching or detaching the transmission member from the acoustic horn or transducer, which may or may not utilize an attachment method; and

g) programmable circuitry including an integrated or onboard programmable digital signal processing chipset to process the monitored, transmitted and received/input signals through algorithms that interrogate the responses, compare the ultrasound feedback and effect on the resonant frequency standing wave, estimate the size of the opening tunneled through the lesion by the activated tip, and modulate the power in the system via voltage amplitude and system frequency.

For purposes of the following description, the system may be considered to be comprised of four main subcomponents and subsystems:

1) a compact housing unit, which may or may not be hand-held, to control the operation of the medical device, and which houses all or some of the signal generator, the ultrasonic transducer, the acoustic horn (although the horn may be part of the transducer assembly, it may be omitted) and interfacing components, as well as data acquisition, processing and system control.

Different embodiments of the device system are envisaged. In one embodiment, all components are grouped in a single unit. In another embodiment, the components are disassembled, wherein the generators are housed separately. In another embodiment, the transducer horns are separate. In another embodiment, the coupling is directly connected to the transducer stack.

2) An attachment and detachment module that allows the pass-through wire to be connected to the ultrasonic transducer and/or horn assembly.

3) A set, plurality or series of interchangeable flexible delivery member assemblies or crossing guidewires for minimally invasive percutaneous surgical recanalization of blocked or partially blocked anatomical passageways.

4) And the integrated signal processing circuit board is used for data acquisition and processing and controlled activation of the system. In some embodiments, the processing board is capable of analog and/or digital signal analysis and power control of the device and incorporation into a communication module. This enables devices and their data to be wired and wirelessly connected to a wider range of data networks and the internet, and facilitates the development of more intelligent algorithms to manage the system.

Operation of

In general, the system operates as follows: a) the signal generator provides electric energy to the transducer; b) the piezoelectric ultrasonic transducer converts electric energy into mechanical vibration; c) these mechanical vibrations may be further amplified by the acoustic horn; d) the customized transmission member is coupled to the acoustic horn or to the transducer via a customized coupling method; e) the ultrasonic vibration is transmitted via the transmission member; f) the distal tip of the transmission member vibrates at a prescribed frequency and amplitude with the ability to beneficially destroy diseased tissue or other matter; and g) digital signal processing and control circuitry allows semi-autonomous overall characterization of lesions, power control and estimated size of openings in the system.

When the ultrasound system is activated, the emitted waves travel along the wire to its distal tip where they are reflected. The reverberation produced in the wire at the different transition points creates a series of secondary and tertiary reflections. These waves have different wire design and characteristic characteristics and can be optimized to enhance the differences in their signal characteristics. These reflections are determined to consist of specific response patterns in the waveform of a given input at any time, and their changes are associated with perturbations or differences in the surrounding environment.

The amplitude of displacement along the wire at a particular frequency varies throughout the procedure due to damping caused by contact with surrounding tissue during navigation to the lesion site or contact with diseased non-compliant or calcified tissue in the lesion. Compensation for these losses is made, for example, by increasing the voltage or current in the generator and then in the transducer. This is used to drive amplification and/or attenuation of the primary ultrasonic energy. Reverberation in the system is affected in a characteristic way, similar to primary losses, which allows them to be used to traverse and excavate lesions and characterize the sources and properties causing damping.

Control of

To achieve a constant vibration amplitude, the ultrasonic transducer is controlled by a suitable feedback controller. In the case of the ultrasonic waveform, the phase feedback control and comparison may be performed by an electrically equivalent model, such as a Butterworth-van Dyke model.

The ultrasonic transducer may be controlled by the frequency and amplitude of the excitation voltage. In embodiments of the invention a way is employed in which varying the frequency affects the phase between the voltage and current. Here, the amplitude of the excitation voltage controls the current and is proportional to the vibration amplitude in the resonance. This allows the control algorithm to drive the frequency with only phase and amplitude.

In a preferred embodiment, the method is to use the resonant frequency as the operating point for control, in conjunction with an amplitude feedback controller to drive the system, and manage this operation by using a custom programmed control algorithm unique to each wire type.

The advantages of a resonant drive, low damping system are the required low voltage and high effective power values. This technique is novel in the context of active guidewire systems. It also provides additional advantages in controlling the response of the nitinol wire system to ultrasonic activation.

Preferably, the wire is activated at a frequency of 40kHz in order to advance to and also through the lesion. The amplitude of the signal is determined by the extent to which it is possible to find resonances in the system due to contact in tortuous pathways or perturbations in contact with lesions forming complete occlusions or thrombi or some embolic material. An activation frequency of 40kHz has been found to be effective in producing a crossing/digging action at and around the distal end portion of the wire and to help drive the wire to and through the lesion.

An activation frequency of 40kHz enables ultrasonic energy to be transmitted over a functional working length of 750mm or less to 2m or more (e.g., 1.5m) for distal tip activation, with sufficient strength to achieve resonance over a range of harmonics, and with sufficient energy to achieve crossing and digging.

Basing the system on an activation frequency of 40kHz also enables the components to be compact enough so that they can be incorporated into a handheld device that is compact in size and convenient in form. For example, using a 20kHz system would require the mass and size (both length and diameter) of the transducer to be multiplied.

The transducer can be designed to have a desired resonant frequency depending on the material properties, geometry and pre-stress of the transducer. In a broad sense, the higher the resonant frequency of the transducer, the smaller its size and overall dimensions. For example, a transducer and horn configuration operating at a frequency of 40kHz can be made hand-held and compact. This is so as to allow the production of a hand-held transducer that can be easily used with a wire. In particular, small transducers can be easily moved along the wire by a single operator, and can be easily stored or fixed at specific locations along the wire.

The concept of such a system has been established to achieve atherectomy and remove lesions as obstructions. Thus, one function of the described apparatus is to accomplish this. However, this product platform offers another function, namely to act as a guidewire to deliver a treatment or therapeutic device to the lesion site. By using ultrasound to temporarily transform the guidewire into an activated wire, the wire is passed through a lesion of any composition, which allows the wire to pass through lesions that cannot be passed through except by a detour technique.

For a given transducer, temperature effects and changing load conditions in nitinol due to interactions with surrounding tissue during the procedure, which could potentially lead to changes in resonant frequency and vibration amplitude, can be compensated for, to a certain extent.

Thus, it is disclosed that in embodiments of the device, differential changes over time and length will be monitored through resonant frequency use control and analysis, in the use of voltage and current, and such interrogation and compensation will be used to characterize the nature of the anatomical structure within the vessel.

Algorithm

The comparison and analysis between the primary emission and the tertiary feedback response in the wire takes into account the variation in characteristic losses, which are typical characteristics of the engagement of active components with different healthy and diseased tissue types. The analysis distinguishes between loss in the blood vessel and loss associated with the lesion as well as between lesions of different composition, in particular calcified lesions and non-calcified lesions.

The resistive load encountered and recorded by the system varies as the active member passes through different anatomical structures. The analog signals are interrogated and conditioned by an onboard Digital Signal Processor (DSP), and the parametric outputs are processed by algorithms to characterize the response and define feedback and effect control.

The characteristic responses to differential changes occurring in different media and in the passage or navigation of wires within vessels through different anatomical structures are used to create different algorithms for: 1) determining a source of loss in the system and compensating for the loss; 2) assessing the arterial vessel tone; and 3) determining the composition details of the lesion. These algorithms provide an automatic level of compensation to the tip of the wire as it comes into contact with compliant, non-compliant and calcified substances, and in the latter amplify the energy in the system to increase cavitation and formation of the primary lumen.

The algorithm can be customized according to the wire type. The range and rate of change and the differential order of change filtered by the signal processing circuit may be used by an algorithm to characterize the nature of the substance through which the wire passes. This can then be communicated to a physician as the procedure is being performed to help define the treatment.

Performance improvements

Advantageously, the algorithm can be trained with reference in vitro and in vivo data. The latter is achieved by embodiments of the device having a communication mode that provides for the transmission of data to and from the device. Thus, by interpolating more data sets from additional procedures built on experience and evidence of use, the operational quality and interpretation of the device can be improved over time, which can be published into iterative generations of control algorithms for the product.

Such onboard, local, and cloud-based algorithm improvements improve the design and operational interface of the device. It also provides more detailed feedback to the physician using the device and facilitates tailoring the operation of the device to accommodate different wire geometries and anatomical structures.

Coupling and arrangement

The ultrasound generator, main housing, circuitry and coupling components remain outside the patient's body. The majority of the length of the components of the delivery member and any peripheral catheters are the only parts of the system that need to enter the patient's body. The proximal section of the transmission member and any peripheral catheter components remain external to facilitate coupling to the main unit and the protocol requirements for manipulation and control.

A first concept of the invention is a detachable active crossing guide wire. In this way, the active crossing wire can be used as a guidewire for subsequent treatment after crossing. This relates to a method of operation in which a crossing wire may be used in both passive and active configurations. The crossing wire may be attached to or detached from the transducer housing at the point of care.

In a preferred method of operation, the intravascular crossing wire may be initially used in an anatomical passageway in a passive mode without ultrasonic vibration. While the wire remains in the anatomical passageway, the proximal end of the crossing wire may then be connected to an acoustic horn/transducer assembly located in the housing as needed to excite or transmit ultrasonic vibrations via the wire acting as a transmission member, resulting in vibrations at the distal tip to effect crossing of the lesion.

After ultrasonic activation, if desired, the crossing wire can then be detached or separated from the acoustic horn located in the housing to return to the passive wire configuration to facilitate further subsequent devices or treatments.

The ultrasonic transducer, horn, coupling means, signal generator, power supply and control circuitry may all be located in the same hand-held, lightweight compact housing unit. In another embodiment, the signal generator is separate and coupled via a connector cable to a compact housing unit containing the transducer and horn. In another embodiment, the entire system can be designed as a disposable device. In another embodiment, the ultrasound transducer, the horn, the coupling device, the generator, and the control circuit may all be located in the same portable compact housing unit and connected to the power source via a cable.

A customized transmission member or wire is disclosed that will function as an intravascular crossing guidewire, designed and customized to effectively transmit vibrational energy over its length and achieve controlled ablation at its distal tip.

Various methods of mechanically coupling the transmission member to an acoustic horn or transducer located in the housing are also disclosed. The coupling arrangement used in reverse may also serve as a decoupling arrangement.

It is also disclosed that the system may include a separate discrete component to quickly detach the delivery member proximally from the overall system, facilitating its use as a tracking guidewire or positioning device.

The coupling and decoupling mechanism may be housed a) in a main housing in which the transducer and horn are housed, or b) as part of a proximal housing that is part of the transmission member assembly.

In another embodiment, the transmission member is pre-coupled to an acoustic horn located in the housing at the manufacturing stage.

The design of the coupling is optimized to achieve efficient transmission and limit undesirable strain and acoustic transmission losses.

The coupling method is designed to facilitate user interaction, coupling, and visual/tactile feedback of the coupling state.

In one embodiment, the transmission member is part of a custom wire assembly having a proximal housing including a coupling and decoupling arrangement and a wire support to minimize losses in energy delivery through the proximal section of the transmission member. Such customized assemblies and proximal wire segments allow for better guidewire control and access during passive crossing. The design of the coupling mechanism is optimized for the transmission of acoustic ultrasonic energy from the transducer and/or acoustic horn. The manner in which the wires are engaged is important to achieve the desired transmission of the actuation force to the distal tip over the length of the waveguide.

The system delivers a controlled level of energy to the transmission member through a custom coupling to achieve minimal losses and can direct the initial deformation of the transmission member to minimize losses and unwanted loading of the transmission member.

The design of the transmission member or waveguide wire is optimized to control the transmission of the wave pattern through different anatomies to the distal tip and through different materials. The morphology of the materials used is important and although they may appear as highly elastic isotropic material morphologies on a macroscopic level, they may have anisotropic micro-morphological features that may delay the onset of cracks or inhibit the progression of cracks.

To deliver destructive vibrations to the lesion site, the present invention contemplates that the customized pass-through wire resonates at the drive frequency of the system. This is achieved by knowing the material properties including speed of sound and density in addition to the resonant properties and numerical modeling of the elongated rod.

The crossing wire may be made from a single piece of drawn wire or may be constructed by joining segments together end-to-end.

Proximal features may be included to enhance coupling of the wire to the ultrasonic drive unit and reduce the risk of fatigue failure. Rather, distal features may be included to enhance performance of navigation and traversal, including optimizing control and maneuverability for tracking wires through the anatomy, and also increasing the achieved opening profile. Additionally, marker bands may be included to provide visibility under fluoroscopy or x-ray. For example, radiopaque markers may indicate the working length of the wire and the crossing tip.

More generally, the present invention allows the introduction of specific features machined into the wire at the proximal and distal ends and over its length to enhance the ability of the wire to pass through lesions, reinforce the wire, enable greater control of the wire, and enable coupling of the wire and efficient transmission of energy through the wire. The composition of the design will vary with the materials used and the intended use.

The geometry of the wire and the materials used are optimized for different application applications. The wire is machined to minimize imperfections and optimize the transport of segments through the material length and over the material length by tightly controlled taper and keying splines.

The material used in the exemplary embodiment is a nickel titanium (nitinol) alloy. In particular, in the case of nitinol alloys, the size and amount of inclusions are tightly controlled in order to limit the likelihood of fracture.

The design and any geometric features of the distal tip are modern manufacturing methods and have optimized geometries to achieve different effects. By way of non-limiting example, these effects include: limiting trauma to the tissue; accelerating the waveguide through different anatomical structures; and limits unnecessary lateral deflection by different types of different lesions. Lesions may be of varying length, diameter or composition, or originate from thrombosis or calcification. The distal tip is also optimized to open or increase the diameter of the passageway to provide a subsequent treatment device, if desired.

The present invention may include a novel semi-automatic control system that may control or modulate the signal applied from the generator to the transducer and horn and thus to the crosswire. Control may be based on feedback from wire-tissue interaction in order to control the signal transmitted to adjust for losses due to damping or increased resistance or to modulate applied force.

Embodiments of the system include visual and tactile feedback indicators that can provide visual, audio, and/or tactile feedback to the user regarding the status of the device and the nature of the tissue being ablated. Such feedback may also indicate the level of force that may be applied to effect ablation and destruction of tissue and advancement through the wire.

The system may include means for providing a manual override to help control the amplitude of the vibrations delivered to the distal tip. This allows the system to be controlled by the user operating the device during the course of a procedure, either through controls and user input mechanisms located on the generator and transmission unit, or autonomously.

The transmission link and controller unit may include a sensory feedback system and haptics that allow the user to sense the extent to which the wire has passed through the lesion.

In the apparatus described herein, the transducer converts the frequency of the mechanical signal at a set short range frequency sweep over a short range frequency to accommodate losses over the length of the wire caused by the interaction and impact of different forces. The speed of the microprocessor allows the device to handle small fluctuations in resonance in real time. Signal processing and analysis of the feedback ensures that optimum mechanical feedback is achieved.

The device operates at a set frequency between 20kHz and 60kHz, preferably between 35kHz and 45kHz, more preferably between 37kHz and 43kHz and most preferably around 40 kHz. The device also operates at a desired low power, for example in the range of 1W to 5W, to reduce the risk of trauma or dissection of the vessel. In addition to automatically controlling the desired low power range, e.g. 1W to 5W, the output of the device may be controlled to allow the user to amplify the power outside this range and thus compensate for accidental interference and ensure a fast and efficient ride through. Thus, the device can also achieve maximum loading at higher power levels (e.g., up to 50W to 100W) to break through challenging lesions and overcome tip attenuation or deflection.

Another objective of the procedure is to use an interrogation feedback signal method to characterize the lesion through which the wire is passing and to collect data about the passed lesion, such as its length and composition, which are aspects of the way the physician is informed that the target lesion can be treated.

This data is also provided to the physician as feedback in tactile and/or visual or audio form on the display to allow the physician to operate the device. For example, in one embodiment, such feedback may allow a physician to monitor the crossing and assess the characteristics of a lesion using a simple backlit screen on the compact housing unit.

In another embodiment, where the user has access to a network, data from the protocol may be captured anonymously to protect the patient secret and transferred from the device to a data storage and processing platform where it may be analyzed in real time or at a later time.

The characteristics of the lesion may also be presented to the user for analysis and interpretation while they are performing the procedure.

In another embodiment, an appendage is used to record and measure the displacement of the wire as it traverses within the vasculature, and the lesion composition is mapped according to the feedback to characterize lesion characteristics as a function of displacement through the lesion.

In another embodiment, the system is supported in a displacement drive that can push the wire over a controlled distance to provide semi-automatic and robotic traversal of the lesion and a more accurate representation of its composition and displacement.

In another embodiment, the active wire is supported in a sliding locking mechanism, wherein the wire can travel through the center of the transducer body, but there is a lock in the transducer, e.g., at its distal end, where the transmission of energy is achieved.

In another mechanism, the activation unit may travel along the length of the wire and be located at a desired point to lock and effect delivery by a sliding locking mechanism.

Drawings

In order that the invention may be more readily understood, reference will now be made, by way of example, to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a system according to the present invention, including a compact housing unit;

FIG. 2 is a perspective view of the system shown in FIG. 1;

FIG. 3 is a schematic side view showing another embodiment in which an ultrasonic generator is housed in a separate unit;

FIG. 4 is a diagram of analog and digital data flow in the system;

FIG. 5 is a flow chart illustrating a preferred method of operation of the system;

FIG. 6 is a diagram showing the operational functional flow of the system;

FIG. 7 is a flow chart illustrating operation of the semi-autonomous intelligent control system of the present invention;

8a, 8b and 8c are schematic side views showing the active wire assembly being then connected to the horn using a suitable mechanical coupling method and separated from the main housing and proximal assembly by a separation method prior to connection to the horn;

FIGS. 9a, 9b and 9c are cross-sectional views showing one embodiment of a joining method;

FIGS. 10 and 11 are enlarged partial cross-sectional views illustrating other embodiments of the linear push-screw connection method;

FIG. 12 is an enlarged partial cross-sectional view showing another embodiment of a joining method using mechanical locking;

FIG. 13 is an enlarged partial cross-sectional view illustrating one embodiment of a screw attachment method employing a radial release mechanism;

FIG. 14 illustrates a coupling method with a proximal interlock feature on the transmission member;

FIG. 15 is a perspective view of a wire release mechanism that breaks or cuts the active wire between opposing blades;

FIG. 16 is a schematic view of a wire release mechanism breaking or cutting an active wire between gear-carried blades actuated by rollers;

FIG. 17 is a schematic view of a wire release mechanism breaking or cutting an active wire between blades carried by a linearly actuated gear;

fig. 18a to 18c are schematic detailed side views illustrating a method of breaking the active wire;

fig. 19 is a cross-sectional side view of a proximal subassembly that can measure the displacement of an active wire as it traverses;

FIG. 20 is a schematic side view showing the housing unit supported by the automated drive system;

FIG. 21 is a cross-sectional side view of one embodiment in which the acoustic horn and transducer assembly has a hollow port through the full length of the assembly with an internal wire connect/disconnect mechanism or locking collet;

FIG. 22 is a cross-sectional side view of an embodiment in which the acoustic horn/transducer assembly of the activation unit has a hollow port through most of the body length of the assembly, but the wire exits the assembly through a side port, enabling the activation unit to be locked along the wire by a mechanism in the transducer tip;

23 a-23 c are schematic side views of an acoustic horn/transducer assembly showing additional methods for connecting active wires;

24 a-24 c are schematic side views of variations of the arrangement shown in FIGS. 23 a-23 c, in which the active wire extends through the full length of the horn/transducer assembly;

25 a-25 c are schematic side views, and FIG. 25d is a schematic perspective view, of a further variation of the arrangement shown in FIGS. 23 a-23 c, with active wires exiting the horn/transducer assembly through side ports;

FIGS. 26 a-26 c are schematic side views, and FIG. 26d is a schematic detail view, of a variation of the arrangement shown in FIGS. 25 a-25 c, wherein the active wire is laterally removable from the horn/transducer assembly in a direction transverse to the longitudinal axis of the active wire;

27 a-27 c are schematic side views showing the housing unit positioned at various longitudinal positions along a proximal portion of an active wire protruding from a patient's body;

FIGS. 28-31 are exploded perspective views of various collet arrangements for securing an active wire to a horn/transducer assembly;

FIGS. 32a and 32b are enlarged perspective views of the chuck as shown in FIG. 30;

FIG. 33 is a schematic cross-sectional side view of a further collet arrangement;

fig. 34a and 34b are schematic side views of further active wires of the present invention;

fig. 35 is a schematic side view of an active wire of the present invention;

FIG. 36 is a perspective view of a variation of the present invention in which the active wire has an angularly offset distal end portion;

fig. 37 is a schematic side view of an active wire similar to that shown in fig. 35 having an angularly offset distal end portion;

fig. 38a and 38b are schematic side views of additional active wires of the present invention including marker bands;

fig. 39 is a schematic side view of another active wire of the present invention;

fig. 40 and 41 are schematic side views of other active wires of the present invention each having an enlarged bulbous distal tip; and is

Fig. 42a to 42c are schematic side views showing the wire of the present invention initially used as an active wire to pass through a lesion and then used as a guidewire to deliver a subsequent device to the lesion.

Detailed Description

Fig. 1 comprises a schematic view of a compact housing unit 2. In this configuration, the compact housing unit 2 includes an ultrasound generator 4, an ultrasound transducer 6 and an acoustic horn 8. The housing unit 2 is connected to an available power supply via a power cable 10.

Fig. 1 also shows an active traverse wire assembly 12 that may be connected to the housing unit 2. The active wire assembly 12 includes a flexible transmission member in the form of a wire 14.

The proximal segment of the active crossing wire assembly 12 includes an attachment module 16 and a detachment module 18, and one or more additional ports 20 are provided. Also shown is the distal section of the active crossing wire assembly 12, including an enlarged view 22 of the distal tip 24 of the wire 14. In this example, the distal tip 24 is bulbous.

When coupled and activated, transducer 6 and wire 14 vibrate at the proximal end with sufficient amplitude so that the distal end of wire 14 is able to effect traversal of the lesion by energy transmitted along wire 14.

For example, the length of the wire 14 may exceed 2 m. For example, a lesion into or through the foot may involve the wire 14 traveling a distance within the vasculature of typically 1200mm to 2000mm, depending on whether an ipsilateral or contralateral approach is selected. In this regard, the wire 14, which tapers distally to a thin wire at its tip, may be navigated to the plantar artery and around the arch of the foot between the dorsal and plantar arteries. However, the present invention is not limited to foot or other peripheral applications and may be used, for example, in coronary applications where the ability of the wire 14 to navigate to and excavate tortuous small diameter arteries is also beneficial.

Fig. 2 also shows the compact housing unit 2 and the active traverse wire assembly 12. Also shown are user input controls 26 and means for providing feedback to the user, here exemplified by a display 28.

The wire 14 may be coupled to the transducer 6 via the acoustic horn 8 or may alternatively be coupled directly to the transducer 6, in which case the acoustic horn 8 may be omitted. For example, referring to fig. 2, the attachment module 16 may attach the wires 14 directly to the transducers 6 within the body of the housing unit 2, below the display 28 of the housing unit 2.

Fig. 3 shows a variant in which the ultrasonic transducer 6 and the acoustic horn 8 are integrated into the compact housing unit 2, while the ultrasonic generator and the circuit 4 are accommodated in a separate generator housing unit 30. In this case, the housing unit is connected to the generator housing unit via a connector cable 32.

Fig. 4 shows the components and elements of the system and the flow of data through the system, including communications. A controller within the housing unit controls the ultrasonic generator to generate a signal that is converted to ultrasonic energy by the transducer. The ultrasonic energy is fed via an optional acoustic horn to an active wire that navigates the vasculature and passes through an occlusion, such as a Chronic Total Occlusion (CTO).

Feedback from the active wire is received by a feedback receiver, amplified by an amplifier and filtered by a series of bandpass filters, and then through analog-to-digital conversion generates feedback data that is sent to a processor. The controller preferably controls the wireless communication system, for example using a Wi-Fi network or bluetooth connection, to receive data from the processor and to transfer the data from the housing unit to the local storage and/or cloud. Fig. 4 also shows means in the housing unit for providing feedback to the user, such as the display and/or the haptic feedback system described above.

Turning next to fig. 5, this shows that the system can be used in either passive or active mode. Initially, an active wire assembly is introduced into an artery, and the distal tip of the wire is navigated to a target obstruction that may be calcified or spread. If the obstruction can be passed without an ultrasonically activated wire, the system is in a passive mode and the obstruction is passed. Conversely, if the occlusion cannot be traversed without ultrasonically activating the wire, the active wire assembly is connected to the housing unit and then ultrasonically activated to effectuate traversal.

Once through the blockage, the active wire assembly is disconnected from the housing unit. The wire is then ready for use as a guidewire to facilitate introduction and navigation of subsequent therapeutic or diagnostic devices as needed.

Figure 6 further summarizes the operation of the system and the procedures and decision points associated with the use of the system.

FIG. 7 is a flow chart summarizing semi-autonomous control of the system. In practice, the system may collect data entered by the user prior to the procedure, such as the expected lesion type and its anatomical location. This data may be coupled with real-time inputs, such as power requirements, as the active wire passes through the lesion.

The system can automatically sense changes in frequency and power and can use onboard algorithms to optimize the performance of the active wire. This information may be fed back to the user via tactile, visual or audio means, such as a display on the housing unit.

The changes in the magnitudes of the input and control parameters of current, voltage and frequency, together with the characteristic capacitance of the transducer, provide a matrix of measurements and controls that are used to determine the required power and characterize the lesion being traversed.

While the input remains constant, the change in current is indicative of the absorbed strain energy or damping effect along the wire, and in particular the distal tip of the wire, as the wire passes through the lesion at the sustained frequency of the system.

Monitoring the current allows the behavior of the wire to be interpreted, and modulation of the voltage allows the power to be amplified and the frequency to be recovered when the wire actuates the contact surface and reduces the deflection. This array of measurements in a small frequency range then allows an overall characterization of the composition of the lesion, whether the lesion is calcified, fibrous or gelatinous throughout its length.

These interpolated feature components are not absolute characteristics of the lesion, but rather indicate its composition and consistency, such as: calcification, rigid compaction or disintegration; or compacted calcified particles with uncompacted fibrosis and hard or soft gels. These characteristics may indicate the nature and severity of the lesion and inform the clinician of the optimal treatment regimen to consider.

The system may also transmit the data and receive optimized performance algorithms via existing wireless or wired communication networks.

Fig. 8a to 8c illustrate an attachment method in which the active traverse wire assembly 12 and the compact housing unit 2 are not initially mechanically coupled together. In this configuration, as shown in fig. 8a, the wire 14 may be used in its passive mode as a conventional guidewire, i.e., without ultrasonic activation.

Fig. 8b shows how the active crossing wire assembly 12 may be mechanically coupled to the housing unit 2 if and when required. In particular, the engagement of the attachment module 16 with the distal end of the housing unit 2 achieves alignment and mechanical coupling of the proximally projecting end portion of the wire 14 within the central hole 34 at the distal end of the acoustic horn 8. Once coupled in this manner, ultrasonic vibrations may be transmitted from the acoustic horn 8 along the wire 14 to traverse the lesion.

After passing through the lesion, fig. 8c shows the wire 14 now separated from the acoustic horn 8 after operation of the separation module 18. Specifically, opposing blades of the separation module 18 are brought together around the wire 14 to break or cut the wire 14. The compact housing unit 2 and the proximal segment of the active crossing wire assembly 12 can now be removed from the wire 14, thus separating all other components from the wire 14.

Fig. 9 a-9 c illustrate one embodiment of the proximal segment of the active crossing wire assembly 12, in particular the attachment module 16. In this embodiment, the wire 14 is mechanically bonded 36 to a screw connector 38 that includes an enlarged head and proximally extending external threads. The head of the screw connector 38 is clamped and engaged by a surrounding sleeve 40 having a longitudinal stepped shape. The narrower tubular distal end of the sleeve 40 provides strain relief around the wire 14.

The sleeve 40 and the head of the screw connector 38 are constrained to rotate together about the central longitudinal axis of the wire 14. For example, the cross-sectional view of fig. 9c shows that the head of the screw connector 38 may have various rotationally asymmetric outer shapes 42 that complement and interlock with corresponding inner shapes of the sleeve 40. However, relative axial movement between the sleeve 40 and the head of the screw connector 38 is possible.

An acoustic horn 8 is shown within the housing unit 2. The acoustic horn 8 includes a central distal threaded bore 44 opposite and complementary to the external threads of the screw connector 38.

When coupled as shown in fig. 9b, the proximal segment of the active crossing wire assembly 12 is axially push connected to the housing unit 2 via snap-in connectors 46, 48. The snap-on connector 46 of the housing unit 2 is integral with an axially retractable tube 50 which is biased distally by a spring 52. Retraction of the tube 50 against the bias of the spring 52 allows the external threads of the screw connector 38 to be threaded into the bore 44 of the acoustic horn 8 by rotating the sleeve 40, which applies a torque to the head of the screw connector 38. Once the threads of the screw connector 38 are fully engaged with the bore 44 of the acoustic horn 8, the sleeve 40 is released and the spring 52 acting on the tube 50 then pushes the proximal section of the active wire assembly 12, including the sleeve 40, away from the wire 14 and acoustic horn 8.

Fig. 10 shows another embodiment of a screw connector, wherein a spring mechanism 54 is located in a proximal segment of active wire assembly 12. The screw connector 38 and the wire 14 are as previously described. The active traverse wire assembly 12 and the housing unit 2 are coupled via a snap-fit structure 56. Fig. 11 shows a variation of the arrangement of fig. 10, further including a distally extending snap-fit segment 58.

Fig. 12 shows the screw connector 38 including a manual push-screw-pull slot entry and locking system 60, best understood here in a perspective detail view of the distal end of the housing unit 2. The proximal section of the active crossing wire assembly 12 includes an inwardly facing lug 62 that initially aligns with an external slot 64 formed in the distal end of the housing unit 2. After lug 62 travels proximally along slot 64, the proximal segment of active-traverse wire assembly 12 rotates about the central longitudinal axis of wire 14. This aligns the lug 62 with a notch 66 formed in the distal end of the housing unit. As shown in the cross-sectional view of fig. 12, the lug 62 distally engages with the notch 66 to lock the proximal section of the active crossing wire assembly 12 to the distal end of the housing unit 2.

Fig. 13 illustrates the radial connector clamp and release mechanism 68. The screw connector 38 is retained by a radial retainer 70, which is initially held in a radially inward position by an axially movable sleeve 72. The retainer 70 transfers torque from the sleeve 72 to the screw connector 38 to thread the external threads of the screw connector 38 into the bore 44 of the acoustic horn 8. Once the screw connector 38 is fully engaged with the acoustic horn 8, sliding the sleeve 72 proximally on the distal section of the housing unit 2 releases the radial retainer 70 to radially spring away from the screw connector 38. This separates the wire 14 from the sleeve 72 and from the rest of the proximal segment of the active wire assembly 12.

Fig. 14 shows a connection arrangement in which the proximal end of the wire 14 has a series of geometric features, such as circumferential ridges 74 that nest within and interlock with a coupling connector 76. The coupling connector 76 has an external thread at its proximal end that engages with the threaded hole 44 at the distal end of the acoustic horn 8.

Turning next to fig. 15-17, these figures illustrate various convenient arrangements for severing the wire 14 to release the wire 14 from the housing unit 2 after successful passage through a lesion.

Fig. 15 shows the internal mechanism of the squeeze action disconnect system 76. The surrounding housing has been omitted for clarity. Here, the wire 14 supports a pair of sharp blades 78 opposed around the wire 14. The blades 78 are integral with resilient levers 80 that, when squeezed together, grip and cut the wire 14 between the blades 78.

Fig. 16 and 17 show blades 82 attached to respective meshing gears 84, one on each side of wire 14. The opposite rotation of the gear 84 brings the blades 82 together to grip and cut the wire 14. In fig. 16, the gears 84 are rotated by the user rolling the exposed side of at least one of the gears 84, which in turn rotates the other gear. In contrast, in fig. 17, the linear button mechanism 86, when depressed, turns one of the gears, which in turn rotates the other gear.

Fig. 18a to 18c show another method of breaking the wire. This involves the creation of sharpness defects and the application of cyclic loads that cause fatigue.

Fig. 18a shows the wire 14 in its original form with a smooth outer surface as it would be used to pass through a lesion. Fig. 18b shows the wire 14 after passing through the lesion, e.g., with a blade score or cut 88. The wire 14 will then rapidly break when vibrated by the transducer at the appropriate frequency with sufficient energy, as shown in fig. 18 c. This is due to crack 90 propagating through the diameter of wire 14 from transverse indentation or notch 88, which serves as a point of weakening or stress concentration to initiate crack 90.

By utilizing ultrasonic energy and the inherent toughness of nitinol, this failure mechanism is readily used to disassemble a crimped nitinol wire. Scoring the surface of the wire 14 creates a scoring defect that concentrates stress. Since the critical crack length of nitinol is relatively low, ultrasonic loading at high amplitudes will cause the wire 14 to break there by creating a full planar strain surface failure.

Fig. 19 shows a measurement accessory 92 that can measure and display the distance that the wire 14 and proximal sheath 94 travel longitudinally relative to the housing 96 and front sheath 98. In this example, the linear scale is etched, printed or molded into the proximal sheath 94. An accessory 92 such as this allows the distance traveled by the distal tip of the wire 14 within the vasculature to be conveniently measured at the proximal end of the wire 14.

Fig. 20 illustrates a linear drive system 100 that can support or otherwise hold the housing unit 2 and can longitudinally advance and retract the housing unit 2 as shown. For this purpose, the drive system 100 comprises a drive mount 102 and a unit 104 comprising a motor, an encoder and a force sensor unit. The drive system 100 facilitates autonomous or robotic insertion and navigation of the wire 14 through the vasculature and through the lesion.

Fig. 21 shows the active wire 14 passing through the threaded ultrasonic transducer and horn assembly 106. The locking collet 108 has a tapped section that is threaded onto the threads to close the spring collet jaws 110. The spring collet chuck 110 clamps to the wire 14 over the long interface. This configuration allows the proximal end of the wire 14 to be fed through the acoustic horn/transducer assembly 106 and connected to the assembly 106 at any of a number of points along the length of the wire 14.

Fig. 22 shows a variation of the arrangement of fig. 21, in which the acoustic horn/transducer assembly 106 has a hollow port through most, but not all, of the length of the body of the assembly 106. In this case, the wire 14 exits through the side port 112 so that the activation unit can be locked at any of a number of points along the wire 14 by a mechanism in the distal tip of the assembly 106.

Fig. 23a to 23c show an arrangement in which the proximal end of the wire 14 is received in a central distal aperture 114 of the acoustic horn 8 within the housing 2. After inserting the wire 14 into the hole 114 as shown in fig. 23a, the twist-lock mechanism 116 on the distal end of the housing 2 is turned to lock the wire 14 to the acoustic horn 8 as shown in fig. 23 b. As shown, the acoustic horn 8 may then feed ultrasonic energy into the wire 14. When ultrasonic activation of the wire 14 is no longer required, the wire 14 can be unlocked from the acoustic horn 8 by reversing the twist-lock mechanism 116 and then can be withdrawn longitudinally as shown in fig. 23 c.

Fig. 24 a-26 d illustrate various additional concepts related to adjustable position activation. They illustrate additional arrangements in which an activation system including a housing 118 containing a transducer/horn 120 can slide and lock or "slide and stick" on the crossing wire 14 and thus be coupled to the crossing wire 14 at any location along the wire 14 outside of the patient's body.

To this end, fig. 24 a-24 c illustrate a variation of the arrangement shown in fig. 23 a-23 c, wherein the central bore 114 in the transducer/horn 120 extends longitudinally through the housing 118 and opens into the distal and proximal ends of the housing 118. This allows the wire 14 to extend through and protrude from both ends of the housing 118, as shown in fig. 24b, thereby allowing the housing 118 to be longitudinally repositioned relative to the wire 14.

In this arrangement, the wire 14 is still longitudinally inserted into the distal end of the transducer/horn 120 as shown in fig. 23a, and is longitudinally withdrawn from the distal end of the transducer/horn 120 as shown in fig. 23 c. Again, the twist-lock mechanism 116 on the distal end of the housing 118 is rotated to lock the wire 14 to the transducer/horn 120, as shown in fig. 23 b.

Fig. 25 a-25 d illustrate that the wire 14 may emerge from the housing 118 through an opening other than the central opening 122 at the proximal end of the housing 118. In the example shown here, the wire 14 exits the transducer/horn 120 through a lateral port 124 that communicates with the central distal opening of the bore 34. A laterally exiting portion of wire 126 extends from port 124 to exit housing 118 through a lateral opening aligned with port 124. Thus, the wire 14 is deflected from the central longitudinal axis of the transducer/horn 120 through an acute angle to exit the transducer/horn 120 laterally.

As previously described, the wire 14 is inserted longitudinally into the distal end of the transducer/horn 120 as shown in fig. 23a and is withdrawn longitudinally from the distal end of the transducer/horn 120 as shown in fig. 23 c. Again, the twist-lock mechanism 116 on the distal end of the housing 118 is rotated to lock the wire 14 to the transducer/horn 120, as shown in fig. 23 b.

In a further variant of the lateral outlet principle shown in fig. 25a to 25c, fig. 26a to 26d show such an arrangement: wherein the wire 14 can be pulled laterally from (and optionally also inserted laterally into) the transducer/horn 120 within the housing 118. As shown in the detail of fig. 26d, the wire 14 is received in a longitudinal slot 130 that can be closed and opened by rotating the pivotable jaw 128 of the acoustic horn 118. When closed, the jaws 128 encircle and engage the wire 14 to couple the wire 14 to the transducer/horn 120. When opened by relative angular movement about the central longitudinal axis, the jaw 128 releases the wire 14 from the transducer/horn 120 to exit the transducer/horn 120 through the slot 130. The housing 118 has corresponding slots 132 that allow the wire to exit the housing 118 laterally to release the wire 14.

In the embodiment shown in fig. 24 a-26 d, because the wire 14 needs to be energized only in the distal direction from the housing 118, the damping material in the housing 118 may prevent or dampen the energizing of the portion of the wire 14 extending proximally from the housing 118. Damping may be achieved using various materials, typically elastomers, such as silicone seals or gaskets. More generally, unwanted excitations may be damped by contact between the wire 14 and the wall of the housing 118 around the side port of the housing 118.

Fig. 27 a-27 c illustrate that a physician can disconnect and reconnect the housing 118 at any location along the outer proximal portion of the wire 14, allowing the wire 14 to be loaded and unloaded as desired. As shown in fig. 27c, the wire 14 may be marked along its length with regular or irregular intervals 133 that are characteristic of harmonics at an activation frequency of, for example, 40kHz, such as λ/2 and λ/4.

The housing 118 may be released from the wire 14, repositioned at specific longitudinal intervals, and reconnected to the wire 14 multiple times as the wire 14 is fed in a forward or distal direction. Generally, the housing 118 or the wire 14 may be moved relative to each other, allowing the physician to move the wire 14 to pass through the lesion or to find a better location for the housing 118 to activate the wire 14 at that location. Removing the sheath 118 from the wire 14 and then recoupling it to the wire 14 allows other devices to be placed or left on the wire 14 and allows the wire 14 to not move during the procedure, greatly enhancing ease of use for the physician.

For example, the housing 118 may be slipped over the wire 14 near the location where the wire 14 enters the introducer sheath 135 and the patient's body 137, as shown in fig. 27 a. Fig. 27b and 27c illustrate other locations where the housing 118 may be coupled to the wire 14. Fig. 27b shows the housing at an intermediate position between the introducer sheath 135 and the proximal end of the wire 14, while fig. 27c shows the housing 118 at a proximal position at or near the proximal end of the wire 14.

Turning next to fig. 28-33, these figures illustrate various connector concepts whose primary goal is to achieve excellent acoustic coupling between the crossing wire and the rest of the system. In this regard, the transducer and the coupling method must work in unison. In particular, the transducer with the coupling interface member optionally including an acoustic horn is designed to resonate at the drive frequency of the system.

For example, the transducer may be constructed of grade 5 titanium or aluminum alloy or steel alloy with a stepped configuration. The shape and size of the transducer is selected to achieve amplification gain while ensuring that the system remains close to its operating resonant frequency. Furthermore, any modification of the distal drive face of the transducer to accommodate the connector must be considered and the resonant response considered.

FIG. 28 shows transducer 134 fitted with a double cone collet 136 and a cap screw 138. Cap screw 138 has an external configuration that facilitates gripping and rotation by a user.

Wire 14 enters through a central hole 140 in cap screw 138, opposite a countersunk hole 142 in the distal face of transducer 134. The wire 14 extends through a collet 136 that is interposed between the base bore 142 and the cap screw 138. The taper at the proximal end of the collet 136 is complementary to the counter-sunk hole 142. Cap screw 138 similarly receives and is complementary to the taper at the distal end of collet 136.

The collet 136 includes a first pair of slits 144 at a proximal end thereof and a second pair of slits 146 at a distal end thereof. Each pair of slits 144, 146 extends longitudinally over more than half the length of the collet 136. The slits 144, 146 of each pair lie in mutually orthogonal planes that intersect along a central longitudinal axis of the collet 136. The second pair of slits 146 is rotated 45 deg. about the central longitudinal axis relative to the first pair of slits 144.

Torque applied to cap screw 138 urges cap screw 138 to longitudinally compress collet 136. Thus, the tapered ends cause and the slits 144, 146 allow the collet 136 to radially compress to grip the wire 14. Advantageously, the collet 136 provides a substantially uniform load pattern based on uniform radial reduction and thus provides uniform gripping of the wire 14, thereby improving energy transfer and fatigue life.

FIG. 29 shows a transducer 148 equipped with a single-cone externally threaded collet 150. The tapered proximal end of the collet 150 has an orthogonal slit 152 similar to the collet 136 of fig. 28. When torque is applied to collet 150 to advance collet 150 along bore 154, collet 150 anchors wire 14 within a complementary threaded bore 154 in the distal end of transducer 148. The complementary taper at the proximal base of the bore 154 then radially compresses the collet 150 to grip the wire 14.

Fig. 30 shows a variation of the arrangement shown in fig. 29, in which the wire 14 extends from the distal end through the full length of the transducer 148 to emerge from the proximal end.

Fig. 31, 32a and 32b illustrate a transducer 156 having a double-tapered reverse locking wire release clip 158. The reverse locking system embodies the concept of mutual alignment and misalignment between pairs of longitudinally separated collet members 160, 162 that are rotatable relative to each other about a common central longitudinal axis. When the longitudinal slots 164 in the collet members 160, 162 are misaligned as shown in fig. 32a, the wire 14 is captured within the collet 158. Conversely, when the longitudinal slots 164 in the collet members 160, 162 are aligned as shown in fig. 32b, the wire 14 exits the collet 158 to be able to exit the collet 158 in a direction transverse to the central longitudinal axis of the collet 158.

Accordingly, cap screw 166 and transducer 156 include a slot 168 that may be aligned in the manner of the embodiment shown in fig. 26c to release wire 14 for lateral removal from transducer 156 or for lateral insertion.

The principle here is that when the clamping torque is released and when the slots 164 in the members 160, 162 of the collet 158 are aligned with each other and with the cap screw 166 and the slot 168 in the transducer 156, the wire 14 may be released from the collet 158. This is accomplished by anchoring the proximal member 162 of the collet 158 to the transducer 156 and applying torque from the cap screw 166 to the distal member 160 of the collet 158 while turning the cap screw 166 to release the clamping force.

The proximal member 162 of the collet 158 may, for example, be positioned onto a splined structure of the transducer 156 to align and lock it against rotation. Distal component 160 of collet 158 may have facets with which cap screw 166 may cooperate to rotate distal component 160 relative to proximal component 162 to the extent necessary to release wire 14.

The collet shown in these embodiments may include an internal reverse taper to optimize the platform length for gripping the wire 14. This advantageously limits point loading on the wire 14 and possible consequent microstructural damage that might otherwise promote the formation of microstructural defects.

Fig. 33 shows an inner expansion collet 168 housed in the head of a transducer 170. In this embodiment, the collet 168 is integrated into the transducer 170 and is thus integral with the device itself. The wire 14 extends through the full length of the collet 168 and projects distally and proximally from the transducer 170.

The transducer 170 shown in FIG. 33 has a tubular body 172 surrounding the collet 168. The collet 168 has an enlarged distal head 174 that projects from the distal end of the body 172 and has a diameter that is greater than the inner diameter of the body 172. An inclined ramp surface 176 on the proximal face of the head 174 abuts against the distal end of the body 172.

A torque screw 178 is provided at the proximal end of the main body 172. An annular backing nut 180 and piezoelectric stack 182 are sandwiched between the torque screw 178 and the body 172.

The collet 168 has a threaded proximal member that is threadedly engaged with the torque screw 178. Thus, the torque screw 178 couples the collet 168, and thus the wire 14, to the transducer 170 to transmit ultrasonic energy from the transducer 170 into the wire 14. In addition, turning the torque screw 178 draws the collet 168 proximally into the body of the transducer 170. As the collet 168 moves proximally relative to the body 172, the inclined ramp surface 176 of the enlarged distal head 174 abuts against the distal end of the body 172 and radially clamps the collet 168 onto the wire 14.

Fig. 34a and 34b show a wire 14 having a substantially straight proximal section 184, a distally tapered intermediate section 186, and a substantially straight distal digging section 188 for passing through a lesion. The distal section 188 has a smaller diameter than the proximal section 184 due to the taper of the intermediate section 186 therebetween. For example, the proximal section 184 may have a diameter of 0.43mm and the distal section 188 may have a diameter of 0.25 mm. Since the length of the intermediate section 186 can extend over a length of one meter, the taper between the proximal section 184 and the distal section 188 is very small and is therefore greatly exaggerated in these figures.

The overall geometry of the wire, including its nominal diameter and length, is determined by the characteristic sound speed in the wire material. The properties depend on the materials selected for the transducer and the wire. The straight and tapered sections of wire are sized at functional intervals of wavelength.

In the case of the nitinol material chosen, λ/2 and λ/4 are determined to be 168mm, 84mm and 42mm in this example. The selected frequency will generate harmonics along the length of the wire and the loading of the wire tip will help establish standing waves for non-characteristic lesions.

The distal section 188 may be tapered or may be uniform in diameter along its length and the harmonics may be λ or at least λ/4. The system can generate harmonics within a certain range.

Since the goal of the activation wire 14 is to excavate the lesion, the dimensions are optimized for excavating as much volume as possible given the waveform. In this regard, fig. 34b shows that distal section 188 of wire 14, once activated, moves in a predominantly longitudinal mode, moves in and out, and also moves in a radial direction, which maps out and digs a larger volume at the distal end through longitudinal movement of wire 14. It is also seen that the distal segment 188 of wire 14 moves in other modes by lateral and undulating movement at the harmonic waves of the secondary mode and the differential harmonics of the resonant wave, depending on the activation frequency and the length of the distal segment 188.

Fig. 35 illustrates how wire 14 may be manufactured from segments welded together end-to-end. In this embodiment, the proximal segment 184 is machined to a standard diameter to provide enlargement and to provide a standard connection for a proximally loaded activation device. The proximal segment 184 serves as a shaft that may be welded at a junction 190, circled in fig. 35, to a selected one of a variety of different diameter wires that may have customized distal ends and tips. This advantageously reduces the requirement to maintain stock with various wire diameters, as several segments of different wire diameters can be assembled to produce wires with many desired configurations. With the weld joint 190 of the wire 14 in a low stress position, the load applied to the joint 190 during activation will not result in catastrophic fatigue failure.

Moving to fig. 36 and 37, these figures show wire 14 formed or shaped with an angularly offset distal digging segment for passing through a lesion. In this embodiment, the distal section is not straight but instead is angled due to the heat-set shaped tip 192. The size of tip 192 is optimized to provide improved performance in steering to and excavating into a lesion. In particular, the angle of tip 192 relative to the longitudinal axis of the distal section and the length of tip 192 determine the ability of wire 14 to transition into a particular side branch artery. The angle and length of tip 192 also affects the manner in which wire 14 will excavate a narrow piece of material once activated.

If the size of the tip 192 is a harmonic characteristic, such as a length of λ/8 or about 22mm, the wire 14 will open a significantly larger tunnel in the lesion than, for example, a 25mm tip section. The amplitude of the waveform and the number of times the distal section of wire 14 passes through the calcified section will determine the diameter of the tunnel being excavated.

If the angle of tip 192 is too large, a larger lever arm is created, thus overstraining wire 14; conversely, if the angle of the tip 192 is too small, the wire 14 may not be manipulated effectively. In this regard, fig. 37 shows that tip 192 can be offset from the longitudinal axis of wire 14 by about 15 ° to 45 °, allowing tip 192 to disrupt and excavate larger volumes of lesions. The tip 192 is suitably heat treated, for example at over 500 c, for less than 10 minutes in order to create a microstructure that reliably resists crack propagation and thus fatigue.

Fig. 38a and 38b show how visibility of the position of the wire 14 in the patient's body is enhanced by using a marker band 194, e.g. gold. For example, such marker bands 194 may be fixed at a location near (e.g., about 3mm from) the distal tip 196 of the wire 14 and also away from the distal end of the proximal section 184, just prior to the beginning of the tapered intermediate section 186. Marker band 194 is placed at a location of minimum load when wire 14 is in use. This minimizes the likelihood that marker band 194 may be removed or that wire 14 may fail at these locations. The marker band 194 is intended to fit flush into a circumferential groove ground around the wire 14.

Fig. 39 shows a variation in which the distal tip 196 of the wire 14 is rounded without sharp transitions. By way of example, in this case, the proximal section 184 may be 1800mm long, the tapered intermediate section 186 may be 84mm long and the distal section 188 may be 10mm long. Again, marker band 194 encircles wire 14 proximate distal tip 196 of wire 14 and the distal end of proximal section 184.

Fig. 40 and 41 show other variations of the wire 14, each having a bulbous distal tip 198 that is rounded to avoid sharp transitions. The bulbous tip 198 may be, for example, 3mm to 4mm in length and may have a diameter just over 0.4 mm.

The wire shown in fig. 40 is otherwise similar to the wire 14 shown in fig. 39 except for its bulbous tip 198.

Likewise, the wire 14 shown in fig. 40 and 41 has a circumferential marker band 194 that can fit flush into a circumferential groove ground around the wire 14. Conveniently, as shown, the bulbous tip 198 may be surrounded by one of the marker bands 194.

In the example shown in fig. 41, the wire has a proximal portion that includes a straight segment 200 and a distally tapered segment 202. Straight section 200 may have a textured surface as shown to improve engagement with the activation device. The proximal portion is welded to an intermediate portion that constitutes the majority of the length of the wire 14. The intermediate portion also includes a straight section 204 and a short distally tapered section 206. Marker band 194 is shown encircling straight segment 204 proximate distally tapered segment 206 of intermediate portion 194. Finally, a short, narrow distal segment 208 extends distally from the intermediate portion 186 to the bulbous tip 198.

Turning finally to fig. 42 a-42 c, these schematic diagrams illustrate how the wire 14 may be initially used as an active wire to traverse the lesion 210 and then used as a guidewire to deliver a subsequent diagnostic or therapeutic device 214 to the lesion 210.

In fig. 42a, the wire 14 is shown extending distally through the introducer sheath 135 and into the patient's body 137. The distal tip of the wire 14 has been navigated through the patient's vasculature 212 to reach the lesion 210. The wire 14 shown here is activated by the activation unit 2 and is thus excavated and passed through the lesion 210 by the vibration of the distal tip.

In this example, the activation unit 2 is shown at the proximal end of the wire 14. However, the activation unit 2 may alternatively be positioned at any one of a plurality of intermediate positions along the proximal portion of the wire 14 protruding from the patient's body 137.

Upon successful passage through the lesion 210 as shown in fig. 42b, the wire 14 is deactivated and left in situ within the patient's vasculature 212. The activation unit 2 is then removed from the wire 14, exposing the proximal end of the wire 14.

The deactivated wire 14 may now be used as a guidewire to deliver a subsequent diagnostic or therapeutic device 214 to the lesion 210, as shown in fig. 42 c. The device 214 may most conveniently be screwed onto the proximal end of the wire 14. In principle, however, the device 214 may alternatively be attached to the wire 14 at any location along a proximal portion of the wire 14 that remains outside of the patient's body 137.