阅读说明：本技术 分析多电极导管信号以确定电生理（ep）波传播矢量 (Analyzing multi-electrode catheter signals to determine Electrophysiological (EP) wave propagation vectors ) 是由 A·戈瓦里 V·格莱纳 Y·帕尔蒂 于 2021-07-01 设计创作，主要内容包括：本发明题为“分析多电极导管信号以确定电生理(EP)波传播矢量”。本发明公开了一种方法,该方法包括接收由与心腔的区域中的组织接触的多电极导管的多个电极获取的多个电生理(EP)信号,以及该电极获取该EP信号的相应组织位置。该区域被分成两个区段。使用由该电极获取的该EP信号,计算该相应组织位置的局部激活时间(LAT),并且找到：该两个区段中具有较小平均LAT值的第一区段和该两个区段中具有较大平均值的第二区段。确定该第一区段中的第一代表性位置和该第二区段中的第二代表性位置。在该第一代表性位置和该第二代表性位置之间计算指示已生成该EP信号的EP波的传播的传播矢量。将该传播矢量呈现给用户。(The invention is directed to analyzing multi-electrode catheter signals to determine Electrophysiological (EP) wave propagation vectors. A method includes receiving a plurality of Electrophysiological (EP) signals acquired by a plurality of electrodes of a multi-electrode catheter in contact with tissue in a region of a heart chamber, and respective tissue locations at which the electrodes acquire the EP signals. The area is divided into two sections. Using the EP signals acquired by the electrodes, the Local Activation Time (LAT) of the respective tissue location is calculated, and: a first of the two segments having a smaller average LAT value and a second of the two segments having a larger average value. A first representative location in the first section and a second representative location in the second section are determined. A propagation vector indicative of propagation of the EP wave that has generated the EP signal is calculated between the first representative location and the second representative location. The propagation vector is presented to the user.)

1. A method, comprising:

receiving (i) a plurality of Electrophysiological (EP) signals acquired by a plurality of electrodes of a multi-electrode catheter in contact with tissue in a region of a heart chamber, and (ii) respective tissue locations at which the electrodes acquire the EP signals;

dividing the area into two sections;

using the EP signals acquired by the electrodes, calculating Local Activation Time (LAT) values for the respective tissue locations and finding a first one of the two segments having a smaller average LAT value and a second one of the two segments having a larger average value;

determining a first representative location in the first section and a second representative location in the second section;

calculating a propagation vector between the first representative location and the second representative location indicative of propagation of an EP wave that has generated the EP signal; and

presenting the propagation vector to a user in a graphical form.

2. The method of claim 1, wherein presenting the propagation vector comprises superimposing an arrow on a map of the cardiac chamber.

3. The method of claim 2, wherein superimposing the arrow includes using a graphical characteristic of the arrow to indicate a velocity of the EP wave between the first representative location and the second representative location.

4. The method of claim 3, wherein the graphical characteristics of the arrow include one or more of: color, length, width, or graphic pattern.

5. The method according to claim 1, and comprising, in the event that a foldback EP wave is detected, calculating an additional propagation vector for the foldback EP wave.

6. The method of claim 5, and comprising superimposing additional arrows on the map of the heart chamber.

7. The method of claim 6, wherein superimposing the additional arrow comprises using a graphical characteristic of the additional arrow to indicate at least one of: the LAT difference and the fold-back cycle time of the fold-back EP wave.

8. The method of claim 1, wherein determining the first representative location comprises determining a tissue location of the tissue locations in the first section having a smallest LAT value, and wherein determining the second representative location comprises determining a tissue location of the tissue locations in the second section having a largest LAT value.

9. The method of claim 1, wherein determining the first representative location comprises calculating a first centroid of the tissue location in the first segment, and wherein determining the second representative location comprises calculating a second centroid of the tissue location in the second segment.

10. The method of claim 9, wherein calculating the first centroid comprises calculating a first weighted average of the tissue locations in the first segment using two or more of the LAT values of the first segment as weights, and wherein calculating the second centroid comprises calculating a second weighted average of the tissue locations in the second segment using two or more of the LAT values of the second segment as weights.

11. A system, comprising:

an interface configured to receive (i) a plurality of Electrophysiological (EP) signals acquired by a plurality of electrodes of a multi-electrode catheter in contact with tissue in a region of a heart chamber, and (ii) respective tissue locations at which the electrodes acquire the EP signals; and

a processor configured to:

dividing the area into two sections;

using the EP signals acquired by the electrodes, calculating Local Activation Time (LAT) values for the respective tissue locations and finding a first one of the two segments having a smaller average LAT value and a second one of the two segments having a larger average value;

determining a first representative location in the first section and a second representative location in the second section;

calculating a propagation vector between the first representative location and the second representative location indicative of propagation of an EP wave that has generated the EP signal; and

presenting the propagation vector to a user.

12. The system of claim 11, wherein the processor is configured to present the propagation vector by superimposing an arrow on a map of the cardiac chamber.

13. The system according to claim 12, wherein the processor is configured to use graphical characteristics of the arrows to indicate a velocity of the EP wave between the first representative location and the second representative location.

14. The system of claim 13, wherein the graphical characteristics of the arrow include one or more of: color, length, width, or graphic pattern.

15. The system of claim 11, wherein the processor is further configured to, in the event that a foldback EP wave is detected, calculate an additional propagation vector for the foldback EP wave.

16. The system of claim 15, wherein the processor is further configured to superimpose the additional arrow on a map of the cardiac chamber.

17. The system of claim 16, wherein the processor is configured to use graphical characteristics of the additional arrows to indicate at least one of: the LAT difference and the fold-back cycle time of the fold-back EP wave.

18. The system of claim 11, wherein the processor is configured to determine the first representative location by determining a tissue location in the tissue locations in the first section having a smallest LAT value, and to determine the second representative location by determining a tissue location in the tissue locations in the second section having a largest LAT value.

19. The system of claim 11, wherein the processor is configured to determine the first representative location by calculating a first centroid of the tissue locations in the first zone and to determine the second representative location by calculating a second centroid of the tissue locations in the second zone.

20. The system of claim 19, wherein the processor is configured to compute the first centroid by computing a first weighted average of the tissue locations in the first segment using two or more of the LAT values of the first segment as weights, and to compute the second centroid by computing a second weighted average of the tissue locations in the second segment using two or more of the LAT values of the second segment as weights.

Technical Field

The present invention relates generally to electrophysiology mapping, and in particular to cardiac electrophysiology mapping.

Background

Invasive cardiac techniques for mapping the Electrophysiological (EP) properties of cardiac tissue have been previously proposed in the patent literature. For example, U.S. patent application publication 2017/0311833 describes an effective system for diagnosing arrhythmias and guiding catheter therapy that may allow for the measurement, classification, analysis, and mapping of spatial EP patterns within the body. The active system may also direct arrhythmia therapy and update the map as therapy is delivered. The efficient system may use medical devices with a high density of sensors having a known spatial configuration for collecting EP data and positioning data. Further, the efficient system may also use the electronic control system to calculate and provide to the user a variety of metrics, derivative metrics, High Definition (HD) maps, HD composite maps, and general visual aids for association with the geometric anatomical model shown on the display device.

As another example, U.S. patent application publication 2017/0042449 describes a system for determining EP data that includes an electronic control unit configured to: acquiring electrophysiological signals from a plurality of electrodes of one or more catheters; selecting at least one electrode cluster (clique) from the plurality of electrodes to determine a plurality of local electric field data points; determining a position and an orientation of a plurality of electrodes; processing electrophysiological signals from at least one cluster of a complete bipolar sub-cluster set to derive local electric field data points associated with the at least one electrode cluster; deriving at least one orientation independent signal from the at least one electrode cluster from information content corresponding to the weighted portion of the electrogram signal; and displaying or outputting to a user or procedure EP information that is independent of catheter orientation.

U.S. patent application publication 2018/0153426 describes a method and system for mapping an anatomical structure that includes sensing activation signals of intrinsic physiological activity with a plurality of mapping electrodes disposed in or near the anatomical structure, each of the plurality of mapping electrodes having an electrode location. A vector field map is generated to identify feature pattern and locations in the vector field map representing directions of propagation of the activation signals at each electrode location according to at least one vector field template. The target locations of the identified signature patterns are identified based on the corresponding electrode locations.

Disclosure of Invention

Embodiments of the present invention provide a method that includes receiving (i) a plurality of Electrophysiological (EP) signals acquired by a plurality of electrodes of a multi-electrode catheter in contact with tissue in a region of a heart chamber, and (ii) respective tissue locations at which the electrodes acquire the EP signals. The area is divided into two sections. Using EP signals acquired by the electrodes, the Local Activation Time (LAT) of the respective tissue location is calculated, and: a first of the two segments having a smaller average LAT value and a second of the two segments having a larger average value. A first representative location in the first section and a second representative location in the second section are determined. A propagation vector indicative of propagation of the EP wave that has generated the EP signal is calculated between the first representative location and the second representative location. The propagation vectors are presented to the user.

In some embodiments, presenting the propagation vector includes superimposing an arrow on a map of the cardiac chamber. In other embodiments, superimposing the arrow includes using a graphical characteristic of the arrow to indicate a velocity of the EP wave between the first representative location and the second representative location.

In some embodiments, the graphical characteristics of the arrows include one or more of: color, length, width, and graphic pattern (such as gradient or dashed line).

In one embodiment, the method further comprises, in the event that a reentry EP wave is detected, calculating an additional propagation vector for the reentry EP wave.

In another embodiment, the method further comprises superimposing an additional arrow on the map of the heart chamber. In another embodiment, superimposing the additional arrow includes using a graphical characteristic of the additional arrow to indicate at least one of: LAT difference and fold-back cycle time of fold-back EP waves.

In some embodiments, determining the first representative location comprises determining a tissue location having a smallest LAT value among tissue locations in the first section, and wherein determining the second representative location comprises determining a tissue location having a largest LAT value among tissue locations in the second section.

In some embodiments, determining the first representative location comprises calculating a first centroid of tissue locations in the first zone, and wherein determining the second representative location comprises calculating a second centroid of tissue locations in the second zone.

In one embodiment, calculating the first centroid comprises calculating a first weighted average of tissue locations in the first segment using two or more of the first segment's LAT values as weights, and wherein calculating the second centroid comprises calculating a second weighted average of tissue locations in the second segment using two or more of the second segment's LAT values as weights.

There is also provided, in accordance with another embodiment of the present invention, a system, which includes an interface and a processor. The interface is configured to receive (i) a plurality of Electrophysiological (EP) signals acquired by a plurality of electrodes of a multi-electrode catheter in contact with tissue in a region of a heart chamber, and (ii) respective tissue locations at which the electrodes acquire the EP signals. The processor is configured to: (a) dividing the area into two sections; (b) using EP signals acquired by the electrodes, calculating Local Activation Time (LAT) values for respective tissue locations, and finding a first of the two segments having a smaller average LAT value and a second of the two segments having a larger average value; (c) determining a first representative location in the first section and a second representative location in the second section; (d) calculating a propagation vector between the first representative location and the second representative location indicative of propagation of the EP wave that has generated the EP signal; and (e) presenting the propagation vector to the user.

The invention will be more fully understood from the following detailed description of embodiments of the invention taken together with the accompanying drawings, in which:

drawings

Fig. 1 is a schematic illustration of an Electrophysiological (EP) mapping system including different possible multi-electrode catheters, according to an embodiment of the present disclosure;

fig. 2A and 2B are schematic distal views of electrodes of one of the catheters of fig. 1 in contact with tissue and measuring Electrophysiological (EP) signals, according to an embodiment of the invention;

FIG. 3 is a schematic distal view of an electrode of one of the catheters of FIG. 1 in contact with tissue and measuring Electrophysiological (EP) signals, according to another embodiment of the invention; and is

Fig. 4 is a flow diagram schematically illustrating a method and algorithm for estimating and presenting propagation vectors of Electrophysiological (EP) waves, in accordance with an embodiment of the present invention.

Detailed Description

SUMMARY

Intracardiac Electrophysiology (EP) mapping is a catheter-based method that is sometimes used to characterize cardiac EP wave propagation abnormalities, such as those that cause arrhythmias. In a typical catheter-based procedure, the distal end of a catheter including a plurality of sensing electrodes is inserted into the heart to sense a set of data points including measurement locations on wall tissue of a heart cavity and a corresponding set of EP signals from which an EP mapping system may generate a map of the heart cavity, such as an EP map.

In particular, for diagnostics, the direction of propagation of the EP waves at a certain region of the wall tissue may also be required. The direction of propagation of the cardiac wave may be obtained by generating a specific EP timing diagram map of the region of the heart chamber, referred to as a Local Activation Time (LAT) map.

However, for any given region, determining the propagation vector of the EP wave in the heart chamber is a time-consuming process. Typically, it is necessary to compute the LATs for a number of locations around the area and then derive a vector from the LATs and the orientation of the locations. The embodiments of the invention described below provide an efficient method for acquiring EP data and automatically calculating such propagation vectors in real time for regions in the heart chamber.

The disclosed methods may use, among other features, various types of multi-electrode catheters, such as basket catheters or multi-arm catheters (e.g.,PentaRaay manufactured by Biosense-Webster^TMOr octalay^TM). The multi-electrode catheter is brought into contact with (e.g., pressed against) tissue at the region of the heart chamber so that its "electrodes" (e.g., the distal tip to which the spine of the basket is connected, or from which the arms originate) are located on the selected heart tissue region, and the electrodes on the spine/arms are brought into contact with wall tissue at the tissue region of the heart chamber to acquire EP signals.

In one embodiment, to calculate the propagation vector, the processor first divides (e.g., arbitrarily) the region of cardiac tissue in which the electrode is located into two segments using a virtual plane containing the axis of the catheter. Then, using the EP signals acquired from each electrode, the processor calculates the LAT values at the electrode locations (i.e., the respective tissue locations) in each segment to find the first of the two segments with the smaller average LAT value and the second of the two segments with the larger average value.

The processor then determines a first representative location in the first section and a second representative location in the second section. The processor calculates a propagation vector between the first representative location and the second representative location indicative of propagation of the EP wave that has generated the EP signal, and presents the propagation vector to the user.

In one embodiment, for a segment with a lower average LAT value, the processor finds the location where there is the smallest LAT value. For sections with higher average LAT values, the processor finds the location where the largest LAT value is located. From the known displacement (distance and direction) between the two locations and the corresponding known time difference of the LAT values, the processor calculates a propagation (e.g., velocity) vector (velocity and direction) of the EP wave. The processor may then draw an arrow corresponding to the vector on the map of the heart chamber. The length of the arrow, its color, or a graphical pattern (e.g., a gradient or shading pattern) may be set to correspond to the velocity.

In another embodiment, rather than computing the velocity vector from the minimum of the LAT values at the segment with the lower average LAT value to the maximum of the LAT values at the segment with the higher average LAT value, the processor computes the vector between the centroid wall tissue location with the lower average LAT value and the centroid wall tissue location with the higher average LAT value. To this end, the processor performs a centroid calculation in a first segment of first wall tissue locations having a lower average LAT value and a centroid calculation in a second segment of second wall tissue locations having a higher average LAT value. The processor then calculates a centroid propagation vector between the first centroid position and the second centroid position of the EP wave that is likely to generate the EP signal, and presents the centroid propagation vector to the user. Centroid calculation typically includes calculating a weighted average of each centroid position using two or more LAT values for each segment as weights.

In some clinical situations, such as reentry arrhythmias, the velocity vector oscillates in a direction (backwards and forwards) when the catheter is in a substantially fixed position. This typically occurs in cases where the catheter is at a junction where the waves actually alternate in direction, for example, blocking tissue due to wave encountering abnormal one-way propagation. In this case, the processor calculates additional vectors and may display the two vectors on the screen as two arrows distinguished by different brightness/thickness/length/color depending on the relative magnitude of the EP waves.

Typically, the processor is programmed in software containing specific algorithms that enable the processor to perform each of the processor-related steps and functions described above.

The disclosed systems and methods for efficient derivation and clear presentation of the propagation direction of EP waves may improve catheter-based arrhythmia diagnosis and treatment protocols.

Description of the System

Fig. 1 is a schematic illustration of an Electrophysiological (EP) mapping system 10 including different possible multi-electrode catheters, according to an embodiment of the present disclosure. The system 10 may be configured to analyze substantially any physiological parameter or combination of such parameters. In the description herein, by way of example, the analyzed signals are assumed to be intracardiac electrocardiogram potential-time relationships. To adequately characterize such relationships, the signals at the various locations need to be referenced to one another in time, such as done during LAT map generation. Temporal referencing is accomplished by measuring relative to a reference time (e.g., time of day), such as the beginning of each QRS complex (i.e., the beginning of each heartbeat) of an ECG reference signal. A method for generating LAT maps is described in the aforementioned U.S. patent 9,050,011.

As described above, the system 10 includes a multi-electrode catheter, which may be the basket catheter 14 or a multi-arm catheter 114 (e.g., PentaRay catheter) among several possible options^TMCatheter), both of which are shown in inset 37. The following description refers collectively to the above catheter options as "catheter 14/114," meaning that the embodiments described below are applicable to any of these multiple-electrode catheter types. Each conduit end 14, 114 extends along a longitudinal axis L-L.

The multi-electrode catheter 14/114 is inserted into a chamber or vascular structure of the heart 12 by the physician 32 through the vascular system of the patient. The physician 32 brings the distal tip 18/118 of the catheter into contact with the wall tissue 19 of the heart chamber 21 at the EP mapping target tissue site (e.g., pressing the tip distally against the wall tissue). The catheter typically includes a handle 20 with suitable control means so that the physician 32 can manipulate, position and orient the distal end of the catheter as required for EP mapping.

Multi-electrode catheter 14/114 is coupled to console 24 so that physician 32 can observe and adjust the function of the catheter. To assist the physician 32, the distal portion of the catheter may contain various sensors, such as a contact force sensor (not shown) and a magnetic sensor 33/133 that provides position, direction, and orientation signals to the processor 22 located in the console 24. Processor 22 may perform several processing functions as described below. Specifically, electrical signals may be caused to travel back and forth between heart 12 and console 24 via cable 34 from electrode 16/116 located at or near distal tip 18 of catheter 14/114. Pacing signals and other control signals may be communicated from console 24 to heart 12 via cable 34 and electrode 16/116.

The console 24 includes a monitor 29 driven by the processor 22. Signal processing circuitry in the electrical interface 34 typically receives, amplifies, filters, and digitizes signals from the conduit 14/114, including signals generated by the above-described sensors and the plurality of sensing electrodes 16. The digitized signals are received and used by console 24 and the positioning system to calculate the position and orientation of catheter 14/114 and to analyze EP signals from electrode 16/116, as described in further detail below.

The respective positions of electrodes 16/116 are tracked during the disclosed protocol. The tracking can be carried out, for example, using a product from Biosense-Webster3 systems. Such systems measure the impedance between electrode 16/116 and a plurality of external electrodes 30 coupled to the patient's body. For example, three external electrodes 30 may be coupled to the chest of the patient and three other external electrodes may be coupled to the back of the patient. (for ease of illustration, only one chest electrode is shown in FIG. 1.) A wire connection 35 connects the console 24 with the body surface electrodes 30 and other components of the positioning subsystem for measuring the position and orientation coordinates of the catheter 14/114. Methods for tracking the position of the electrodes 16 based on electrical signals, known as active current position (ACL), are implemented in various medical applications, such as those described above3, in the system. Details of ACL subsystems and methods are provided in U.S. patent 8,456,182, which is assigned to the assignee of the present patent application and the disclosure of which is incorporated herein by reference and copies are provided in the appendix.

In some embodiments, in addition to or instead of the ACL tracking subsystem, the system 10 includes a magnetic localization tracking subsystem that determines the position and orientation of the magnetic sensor 33 at the distal end of the catheter 14/114 by generating magnetic fields in a predefined working space using the field generating coils 28 and sensing these fields at the catheter. Since electrodes 16/116 have known positions on arms 15/115 and known relationships to each other, once catheter 14/114 is magnetically tracked in the heart, the position of each of electrodes 16/116 in the heart becomes known. Suitable magnetic position tracking subsystems are described in U.S. patents 7,756,576 and 7,536,218, which are assigned to the assignee of the present patent application and the disclosures of which are incorporated herein by reference and copies are provided in the appendix.

Based on the EP signals from the electrode 16/116 with tracked locations, electrically active maps may be prepared according to the methods disclosed in U.S. patents 6,226,542, 6,301,496, and 6,892,091, which are assigned to the assignee of the present patent application and the disclosures of which are incorporated herein by reference and the copies are provided in the appendix.

Processor 22 operates system 10 using software stored in memory 25. The software may be downloaded to processor 22 in electronic form, for example, over a network, or alternatively or in addition to, the software may be provided and/or stored on non-transitory tangible media, such as magnetic, optical, or electronic memory. In particular, the processor 22 runs a dedicated algorithm, included in fig. 4, as disclosed herein, which enables the processor 22 to perform the disclosed steps, as described further below.

The exemplary illustration shown in fig. 1 was chosen purely for the sake of conceptual clarity. Other types of EP Sensing geometries may also be employed, such as the balloon Catheter including electrode segments described in U.S. patent application 16/708285 (attorney docket No. BIO6163USNP) entitled "Catheter with compliance of Sensing Electrodes Used as Electrodes," filed on 9/12/2019, the disclosure of which is incorporated herein by reference (copies are provided in the appendix).

System 20 generally includes additional modules and elements that are not directly related to the disclosed technology and, therefore, are intentionally omitted from fig. 1 and the corresponding description. The elements of system 20 and the methods described herein may further be applied, for example, to control ablation of tissue of heart 12.

Analyzing multi-electrode catheter signals to determine EP wave propagation vectors

Fig. 2A and 2B are schematic distal views of an electrode 16/116 of one of the catheters of fig. 1 in contact with tissue and measuring an Electrophysiological (EP) signal, according to an embodiment of the invention. These figures further illustrate the tissue 50 as viewed in the distal direction from a proximal location of the ridge or arm on the axis L-L of the catheter and the distal portion 40 of the ridge or arm 15/115 of the catheter 14/114 pressed against the tissue 50. The ridges or arms 15/115 are coupled together at the distal tip 18/118 of the catheter.

In some embodiments, processor 22 divides the spine/arm into two segments using a virtual plane 55 that includes the axis L-L of the catheter. Processor 22 may select the section, i.e., selection plane 55, arbitrarily or according to some selection criteria. For example, the virtual plane 55 is configured to intersect the central longitudinal axis L-L of the catheter and may not intersect either of the ridges or arms of the catheter 14 or 114. Then, using the EP signals acquired from each electrode 16/116, the processor calculates LAT values at the electrode positions in each segment. The processor 22 then finds which of the two sections (S1 or S2) is characterized by a lower average LAT value (e.g., has a lower average LAT value in both sections) and which is characterized by a higher average LAT value (e.g., has a higher average value in both sections).

In the embodiment shown in fig. 2A, the virtual plane 55 divides the ridge or arm into two sections: a first section S1 with a lower average LAT value and another or second section S2 with a higher average LAT value. The first segment S1 is determined by the processor to find the minimum LAT value and its position is determined to be at point 60 (which may be the position of the sensing electrode on the spine or arm of catheter 14 or 114). For the other or second segment S2 with a higher average LAT value, the processor finds the maximum LAT value and its location 66 (which may be the location of the sensing electrode on the spine or arm of the catheter 14 or 114). Locations 60 and 66 are referred to herein as "representative locations" because each of them represents its entire respective section by a single data point.

From the known displacement (distance and direction) between the two representative locations and the known time (difference in LAT values), the processor calculates the velocity vector (velocity and direction) of the EP wave 100, which generates a signal as it propagates in the tissue below the catheter. The processor may then draw an arrow 65 corresponding to the vector on the map of the heart chamber and provide it in the display screen 29. The length of the arrow 65 and/or its color may be set to correspond to the rate.

In the embodiment shown in fig. 2B, instead of computing the velocity vector from the minimum of the LAT values at the zone with the lower average LAT value to the maximum of the LAT values at the zone with the higher average LAT value, a vector is computed between the centroid positions of the lower average LAT value and the higher average LAT value, where the centroid position is found using the following formula:

equation 1

In fig. 2B, by way of example, for each centroid position, i is 1, 2. That is, centroid wall tissue location 70 is calculated by equation 1 using the LAT values and corresponding locations 68 and 72, and centroid wall tissue location 80 is calculated using the LAT values and corresponding locations 78 and 82. The processor may then draw arrow 75 corresponding to the vector between positions 70 and 80. Thus, in the example of fig. 2B, the centroids of the two segments (locations 70 and 80) are used as representative locations. In alternative embodiments, processor 22 may select the representative location in the two sections in any other suitable manner.

The illustrations in fig. 2A and 2B are conceptual and are given by way of example. The actual catheter configuration may vary. For example, the number of ridges or arms may be greater than shown.

Fig. 3 is a schematic distal view of an electrode 16/116 of one of the catheters of fig. 1 in contact with tissue and measuring an Electrophysiological (EP) signal, according to another embodiment of the invention. Catheter 14/114 is the same layout as in fig. 2A and 2B, but the catheter is placed at a different tissue location where EP buckling occurs.

As described above, in the case of a reentry arrhythmia, the velocity vector at this region may oscillate in the directions (backward and forward). This typically occurs where the catheter is at a junction where the EP wave 100 actually alternates in direction, for example, as a result of the wave encountering abnormal unidirectional propagation blocking tissue 52. In this case, two EP wave vectors (one for the incident EP wave 100 and the other for the return EP wave 102) may be displayed on the screen with two respective arrows 95 and 97, each having a different brightness/thickness/length/color depending on the relative magnitude of the EP waves. In fig. 3, a vector is calculated using the centroid calculation method of fig. 2B. One corresponding vector points from centroid position 90 to centroid position 99 and the other vector points from centroid position 91 to centroid position 97.

Fig. 4 is a flow diagram schematically illustrating a method and algorithm for estimating and presenting a propagation vector of an Electrophysiological (EP) wave 100, according to an embodiment of the present invention. In accordance with the presented embodiment, the algorithm performs a procedure that begins with physician 30 pressing catheter 14/114 against a region of cardiac tissue to bring a portion of electrode 16/116 into contact with the tissue at catheter placement step 400.

Then, at a measurement step 402, the system 10 measures the electrode location on the wall tissue 19 of the heart chamber 21 and the corresponding EP signal set at that location generated by the EP wave 100.

Next, processor 22 arbitrarily divides the region into two sections at a region dividing step 404.

Next, processor 22 calculates the LAT values at each electrode position, at a LAT calculation step 406.

Next, processor 22 calculates an average LAT value for each segment, at an average LAT calculation step 408. Typically, one segment has a lower average LAT value than another segment.

Next, at an average LAT-position-calculating step 410, processor 22 calculates centroid positions for the lower average LAT values and the higher average LAT values using the method described in fig. 2B.

Using the centroid position, processor 22 calculates a centroid EP wave propagation vector for EP wave 100, at a vector calculation step 414.

Finally, at a propagation vector rendering step 410, processor 22 superimposes (e.g., draws) an arrow corresponding to the vector on a map of the heart chamber, as shown by display 29 in fig. 1. The length of the arrow 65 or 75 and/or its color may be set to correspond to the rate.

The exemplary flow chart shown in fig. 4 was chosen solely for the purpose of conceptual clarity. This embodiment also includes additional steps of the algorithm, such as operating other sensors mounted on the catheter (such as contact force sensors), which have been intentionally omitted from the disclosure herein in order to provide a more simplified flow diagram.

It will be appreciated that the embodiments described above are cited by way of example, and that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art. Documents incorporated by reference into this patent application are considered an integral part of the application, except that definitions in this specification should only be considered if any term defined in these incorporated documents conflicts with a definition explicitly or implicitly set forth in this specification.