Projection of activation wave velocities onto mapping lumen

Abstract

A method includes receiving an electrophysiological (EP) map of a cardiac cavity, the EP map including data points, the data points including respective locations and EP values. The EP map is projected onto a sphere, which is divided into a grid of unit regions. For at least some of the unit regions, most likely data points representing EP activation in the unit regions are estimated. The representative data point is inversely mapped onto the EP map. The updated EP map with the inverse-mapped representative data points is presented to the user.

Description

Technical Field

[0001] The present disclosure relates generally to electrophysiological (EP) mapping, and in particular to methods for improving the accuracy of cardiac EP maps. Background Art

[0002] Methods of cardiac mapping have been previously described in the patent literature. For example, U.S. Pat. No. 10,136,828 describes electroanatomical mapping performed by inserting a multi-electrode probe into the heart of a living subject; recording concurrent electrograms from electrodes at corresponding locations in the heart; defining corresponding activation time intervals in the electrograms; generating an electrical propagation wave map from the activation time intervals; maximizing the coherence of the waves by adjusting local activation times within the activation time intervals of the electrograms; and reporting the adjusted local activation times.

[0003] As another example, U.S. Patent No. 10,198,876 describes a system and method for visualizing and analyzing arrhythmias using a 2-D planar projection and a partially unfolded surface mapping process. A method for projecting a 3D surface geometry onto a planar projection includes: obtaining a 3D geometry of a cardiac chamber surface using an algorithm that generates angles and distances between points on the cardiac chamber surface representing mapping information; applying a cutting curve to at least two points on the cardiac chamber surface; and at least partially unfolding at least a portion of the cardiac chamber surface along the cutting curve to form a planar protrusion that optimally maintains the angles and distances between points on the cardiac chamber surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The present disclosure will be more fully understood through the following detailed description of examples of the present disclosure in conjunction with the accompanying drawings, in which:

[0005] Figure 1 is a schematic illustration of a catheter-based electrophysiological (EP) mapping system according to an example of the present disclosure;

[0006] Figure 2 is a schematic illustration of a 2D spherical model of an EP map of the left atrium (LA) according to an example of the present disclosure;

[0007] Figure 3 According to the example of the present disclosure Figure 2 A schematic illustration of inverse mapping of EP values ​​statistically determined using a 2D spherical model of the left atrium (LA) onto an EP map; and

[0008] Figure 4 is a schematic diagram of an example according to the present disclosure. Figure 2 Statistical analysis was used to correct the 2D spherical model. Figure 3 Flow chart of a method of EP mapping. DETAILED DESCRIPTION

[0009] Overview

[0010] Electrophysiological (EP) cardiac mapping is commonly used to identify potential sources of arrhythmias in cardiac tissue. Physicians typically use the well-known coherence type of EP mapping to visualize the global pattern of activation in the cardiac chamber of interest. In the context of this specification, the term "coherence" refers to the EP activation wave propagation description, in which the conduction velocity is both cyclic and continuous. To this end, the mapping system can use the anatomical location of the catheter acquisition and the local activation time (LAT) acquired at the corresponding location to construct such a coherence map. The coherence map includes arrows showing the magnitude and direction of the activation wave. Physicians can use other EP map types to characterize arrhythmias, such as bipolar potential maps.

[0011] Regardless of the EP map type, various noises during catheter acquisition may produce inaccuracies in the EP map at specific locations on the heart chamber. Therefore, the physician may want to sample more data points (e.g., locations and EP signals associated with these locations) in order to improve the accuracy of the EP map in a specific area of ​​the heart chamber. In addition, the physician often wants to recheck the activation pattern after the ablation procedure to check whether the ablation has successfully cut off the abnormal transmission of the activation wave across the region of interest (ROI), which usually requires the physician to re-map the signal.

[0012] In some examples of the disclosure described herein, more than one data point is collected at a particular location, e.g., the collected data points are temporally dispersed. The disclosed method uses a collection of data points at a particular region to improve the accuracy of an EP map. For example, when signals are collected by a catheter, a processor can store the magnitude and direction values ​​calculated for each point in each region. The accumulation of data for each such region can provide correction and / or improvement to the maps in these regions, which can be used for local correction or updating of the maps.

[0013] In one example, the processor models the anatomy of the cardiac chamber as, for example, a sphere with a grid, and performs mapping (e.g., projection) of the EP map anatomy onto the sphere, or (f,q) mapping of the anatomy. The projection produces a surface area on the sphere that can be defined by 2D coordinates (q,f). 2D mapping is possible because EP maps are not typically associated with thickness. The processor divides the 2D surface into unit areas according to the grid (one possible choice is (Dq,Df) slices). For a given area, the processor saves the data points collected in the area during the EP mapping procedure and associates the data with a specific location. Analysis on the 2D spherical model is much more efficient than analysis on the EP map itself, and therefore, an improved map can be generated (and refreshed) in real time, for example by inverse mapping (e.g., back-projecting) the spherical data points onto the EP map anatomy using the disclosed techniques, as described below. Figure 2 Described in .

[0014] In some examples, the processor determines a statistically robust representative EP value for each unit area based on multiple data points collected for the area. To this end, the processor uses a suitable optimization algorithm (e.g., a genetic algorithm or a Wisdom of Crowd (WoC) algorithm). In some examples, a confidence level layer is added to indicate to the physician how robust the EP map is in each position. The confidence level can indicate, for example, the probability that the statistically determined representative EP value is true.

[0015] Furthermore, the processor may also locally correct the anatomical shape of the EP map using the statistically determined positions of the unit areas themselves.

[0016] Typically, the processor is programmed with software containing specific algorithms that enable the processor to perform each of the processor-related steps and functions listed above.

[0017] System Description

[0018] Figure 1 is a schematic illustration of a catheter-based electrophysiological (EP) mapping system 21 according to an example of the present disclosure. Figure 1 A physician 27 is depicted using an electroanatomical mapping catheter 29 to perform electroanatomical mapping of a heart 23 of a patient 25. The mapping catheter 29 includes one or more arms 20 at its distal end, each of which is coupled to a bipolar electrode 22 including adjacent electrodes 22a and 22b. For example, any of the electrodes 22 can be used in a monopolar acquisition mode by acquiring intracardiac potentials relative to an external electrode 24 attached to the skin of the patient's 25 chest.

[0019] During the mapping procedure, the position of the electrode 22 is tracked while it is located inside the patient's heart 23. To this end, electrical signals are transmitted between the electrode 22 and the external electrodes 24. For example, three external electrodes 24 may be coupled to the patient's chest and another three external electrodes may be coupled to the patient's back. For ease of illustration, Figure 1 Only one external electrode is shown in FIG. 1. In some examples, the distal end of the catheter includes a magnetic sensor (not shown) that allows magnetically tracking the position of the electrode 22 or calibrating the aforementioned electrical tracking signal to improve the accuracy of the electrical position tracking method.

[0020] Based on these signals and in view of the known positions of the electrodes 24 on the patient's body, the processor 28 calculates an estimated position of each electrode 22 within the patient's heart. Using the electrodes 22, corresponding electrophysiological data, such as a bipolar electrogram trace, is additionally acquired from the tissue of the heart 23. Thus, the processor 28 can associate any given signal received from the electrode 22 (such as a bipolar EP signal) with the location where the signal was acquired. The processor 28 receives the resulting signals via the electrical interface 35, and uses the information contained in these signals to construct an electrophysiological map 31 and an EGM or ECG trace 40, and presents these signals on the display 26. The EGM or ECG trace 40 is also stored in the memory 33 for use by the disclosed algorithm. One tracking system and method capable of generating the map 31 is used in various medical applications (e.g., in the CARTO TM The Advanced Current Localization (ACL) system implemented in the system is described in detail in U.S. Pat. No. 8,456,182, the disclosure of which is incorporated herein by reference. Magnetic position tracking systems (not shown) and methods capable of producing a map 31 or improving the accuracy of the ACL method are described in U.S. Pat. Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, 6,332,089, PCT Patent Publication WO 96 / 05768, and U.S. Patent Application Publication Nos. 2002 / 0065455 A1, 2003 / 0120150 A1, and 2004 / 0068178 A1.

[0021] The processor 28 typically comprises a general purpose computer having software programmed to perform the functions described herein. The software may be downloaded to the computer in electronic form over a network, for example, or it may alternatively or additionally be provided and / or stored on a non-transitory tangible medium such as magnetic, optical, or electronic memory. Specifically, the processor 28 operates as disclosed herein and includes Figure 4, which enables the processor 28 to perform the disclosed steps, as further described below.

[0022] Figure 1 The example illustrations shown are chosen solely for conceptual clarity. Other types of electrophysiological sensing catheter geometries may be employed, such as Catheter (produced by Biosense-Webster, Inc., Irvine, California). In addition, a contact sensor can be mounted at the distal end of the mapping catheter 29 to transmit data indicating the physical quality of the electrode-tissue contact. In an example, if the physical contact quality of one or more electrodes 22 is indicated as poor, their measurements can be discarded, and if the contact quality of other electrodes is indicated as adequate, their measurements can be considered valid.

[0023] 2D Modeling of EP Mapping of Cardiac Chambers

[0024] Figure 2 is a schematic illustration of a 2D spherical model 204 of an EP map 202 of the left atrium (LA) according to an example of the present disclosure. As can be seen, the LA has features including four pulmonary veins (PVs), a left atrial appendage (LAA), and a mitral valve (MV). Acquiring data points in the LA can be challenging, resulting in local inaccuracies in the EP map 202, as discussed above. The heart chamber shape is still simple enough to be (f,q) mapped onto the sphere 204, and using statistical analysis of the sphere, the disclosed techniques can improve the accuracy of the map 202, as discussed below and Figure 3 As described in.

[0025] As in Figure 2 As seen in FIG. 2 , a sphere 204 has a spherical grid 210 defined by angular segments 208 from an origin 206 of the sphere 204. Each angular segment 208 corresponds to a unit area 212, and the size of the area 212 may be predefined or updated depending on, for example, the desired spatial resolution or robustness to statistical corrections of the EP map 202. The area 212 is typically measured in mm. 2 .

[0026] As the disclosed technology aims to improve the accuracy of EP mapping, additional acquisition by the catheter provides multiple data points 216 in the same area 212 of the sphere 204, particularly in the required position 215 of the heart chamber. The acquired data points 216 can be, for example, the magnitude and direction of the detected activation. In some example embodiments, the processor 28 can evaluate the data points acquired in the area 212 over time and select the most likely data point representing the activation in the area. Alternatively or additionally, the processor can evaluate the data points acquired in the area 212 and identify outliers based on comparing the data points with the identified representative data points. Optionally, a statistical analysis is performed to select the most representative data points. Optionally, a collective intelligence algorithm is used for this purpose. The processor then applies statistical analysis to the data points 216 in each area 212 to statistically determine the representative EP value therein. In the case where the EP value sought is the local activation velocity, an example of the statistical analysis is given in the form of an activation velocity histogram 214. There can be 10-100 or more points per unit area. The output of the collective intelligence algorithm is a single representative point per unit area. The processor can calculate the magnitude and direction of the EP propagation signal of the heart for each unit area.

[0027] Figure 3 According to the example of the present disclosure Figure 2 Schematic illustration of inverse mapping (303) of a 2D spherical model 204 of a left atrium (LA) EP map 202 of a statistically determined representative EP value. In the context of the present disclosure, inverse mapping is a mathematical operation, such as back-projection or other conformal transformation, of a set of data points overlaid on a sphere into an anatomical surface from which the data points are projected onto the sphere.

[0028] As can be seen, there is a need to make the EP map more accurate in region 312 of the map, which corresponds to one or more regions 212 on sphere 202. Specifically, there is a need to know the activation velocities therein more accurately, for example, to determine whether the region is pro-arrhythmic. Using the disclosed techniques, the processor inversely maps (303) the analysis results from region 212 of sphere 204 onto region 312 in the form of statistically determined EP values ​​from which activation velocities 318 are derived, which makes the EP map more clinically meaningful in terms of activation wave propagation paths.

[0029] Method for correcting EP maps using statistical analysis of 2D spherical models

[0030] Figure 4 is a schematic diagram for describing the use of an example according to the present disclosure. Figure 2 Statistical analysis of the 2D spheroid model 204 to correct Figure 3Flow chart of a method for obtaining an EP map 202 of a heart chamber. The algorithm execution process according to the proposed embodiment begins with the processor 28 receiving an EP map 202 of a heart chamber at an EP map receiving step 402, the EP map including data points including corresponding positions and EP values.

[0031] At an (f,q) mapping step 404 , processor 28 projects EP map 202 onto sphere 204 that is divided into a grid 210 of unit regions 212 (also referred to herein as “grid regions”).

[0032] Next, at the statistical analysis step 406 , for at least some of the unit areas, the processor statistically analyzes the data points falling into each unit area to determine a representative EP value of the unit area (eg, grid area).

[0033] At a back-mapping step 408 , the processor back-maps (eg, back-projects) the representative EP values ​​onto the EP map 202 .

[0034] Finally, at an EP map presentation step 410 , processor 28 presents EP map 202 with inverse-mapped representative EP values ​​to the user.

[0035] Figure 4 The flowchart is given by way of example. As another example, different grid systems can be used for the sphere model.

[0036] Example

[0037] Example 1

[0038] A method includes receiving an electrophysiological (EP) map (202) of a cardiac chamber, the EP map including data points including corresponding positions and EP values. The EP map is projected onto a sphere (204) divided into a grid (210) of unit areas (212). For at least some of the unit areas (212), the most likely data points representing EP activation in the unit areas are estimated. Representative data points are inverse mapped onto the EP map (202). An updated EP map with the inverse mapped representative data points is presented to a user.

[0039] Example 2

[0040] The method according to embodiment 1, wherein estimating the most likely data point comprises using a wisdom of collectives (WoC) algorithm.

[0041] Example 3

[0042] The method according to any one of claims 1 to 2, wherein the grid is a spherical grid.

[0043] Example 4

[0044] The method of any one of embodiments 1 to 3, and comprising receiving additional data points and projecting the additional data points onto the grid (210), evaluating the data points and the additional data points to redetermine the most likely data points representing the activation of one or more of the unit areas, back mapping the redetermined representative data points, and refreshing an updated EP map view presented to the user to reflect the redetermined representative data points.

[0045] Example 5

[0046] A method according to any one of embodiments 1 to 4, and comprising calculating a confidence level associated with one or more of the representative data points and presenting it to the user.

[0047] Example 6

[0048] Embodiment 1: The method of any one of embodiments 1 to 5, wherein the data point comprises a local activation velocity.

[0049] Example 7

[0050] Embodiment 6: The method of any one of embodiments 1 to 6, wherein the data point comprises a local activation time (LAT) of an activation wave.

[0051] Example 8

[0052] Embodiment 1: The method of any one of embodiments 1 to 7, wherein the data points comprise local potentials.

[0053] Example 9

[0054] A system includes an interface (35) and a processor (28). The interface (35) is configured to receive an electrophysiological (EP) map (202) of a cardiac chamber, the EP map including data points, the data points including corresponding positions and EP values. The processor (28) is configured to: (i) project the EP map (202) onto a sphere (204), the sphere being divided into a grid (210) of unit regions (212), (ii) for at least some of the unit regions, estimate the most likely data points representing EP activation in the unit regions, (iii) inverse map representative data points onto the EP map, and (iv) present an updated EP map with the inverse mapped representative data points to a user.

[0055] Although the examples described herein are primarily directed to cardiac diagnostic applications, the methods and systems described herein can also be used in other medical applications.

[0056] It should be understood that the above examples are cited by way of example, and the present disclosure is not limited to what is specifically shown and described above. On the contrary, the scope of the present disclosure includes combinations and sub-combinations of the various features described above, as well as variations and modifications thereof, which will occur to those skilled in the art upon reading the above description and which are not disclosed in the prior art.

Claims

1. A method comprising: receiving an electrophysiological (EP) map of a cardiac chamber, the EP map comprising data points, the data points comprising corresponding positions and EP values; projecting the EP map onto a sphere, the sphere being divided into a grid of unit areas; estimating, for at least some of the unit areas, most likely data points representing EP activation in the unit areas; inverse mapping representative data points onto the EP map; and An updated EP map with inverse mapped representative data points is presented to the user.

2. The method according to claim 1, wherein: Estimating the most likely data point involves using a Wisdom of Crowds (WoC) algorithm.

3. The method according to claim 1, wherein: The grid is a spherical grid.

4. The method according to claim 1, and comprising: Receiving additional data points, projecting the additional data points onto the grid, estimating the data points and the additional data points to redetermine the most likely data points representing the activation of one or more of the unit areas, inverse mapping the redetermined representative data points, and refreshing the updated EP map view presented to the user to reflect the redetermined representative data points. 5 . The method of claim 1 , and comprising calculating and presenting to the user a confidence level associated with one or more of the representative data points.

6. The method according to claim 1, wherein: The data points include local activation velocities.

7. The method according to claim 1, wherein: The data point includes the local activation time (LAT) of the activation wave.

8. The method according to claim 1, wherein: The data points include local potentials.

9. A system comprising: an interface configured to receive an electrophysiological (EP) map of a cardiac chamber, the EP map comprising data points including corresponding locations and EP values; and A processor, the processor being configured to: projecting the EP map onto a sphere, the sphere being divided into a grid of unit areas; estimating, for at least some of the unit areas, most likely data points representing EP activation in the unit areas; inverse mapping representative data points onto the EP map; and An updated EP map with inverse mapped representative data points is presented to the user.

10. The system according to claim 9, wherein: The processor is configured to estimate the most likely data point by using a wisdom of collectives (WoC) algorithm.

11. The system according to claim 9, wherein: The grid is a spherical grid.

12. The system according to claim 9, wherein: The interface is further configured to receive additional data points, and wherein the processor is further configured to project the additional data points onto the grid, estimate the data points and the additional data points to redetermine the most likely data points representing the activation of one or more of the cell areas, inverse map the redetermined representative data points, and refresh the updated EP map view presented to the user to reflect the redetermined representative data points.

13. The system according to claim 9, wherein: The processor is further configured to calculate and present to the user a confidence level associated with one or more of the representative data points.

14. The system according to claim 9, wherein: The data points include local activation velocities.

15. The system according to claim 9, wherein: The data point includes the local activation time (LAT) of the activation wave.

16. The system of claim 9, wherein: The data points include local potentials.

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