Location-based pattern matching of coronary sinus (CS) signals

Abstract

A method includes, during the occurrence of an arrhythmia, acquiring sets of reference coronary sinus electrophysiology (CS-EP) signals with a first catheter in a coronary sinus (CS) of a patient's heart while measuring a plurality of respective reference CS locations of the first catheter. One or more intracardiac electrophysiological (IC-EP) signals are acquired with a second catheter located in a heart cavity of the heart, while actual CS-EP signals are acquired with the first catheter, and an actual CS position of the first catheter is measured at the same time. A reference CS-EP signal is identified using the reference CS location. A signal stability measure between the actual CS-EP signal and the identified reference CS-EP signal is estimated. If the signal stability measure is above a given threshold, then the identified reference CS-EP is utilized to verify whether one or more IC-EP signals acquired by the second catheter are acquired during the occurrence of the arrhythmia.

Description

Technical Field

[0001] The present disclosure relates generally to electrophysiological (EP) sensing using a catheter, and in particular to EP signal acquisition using pattern matching (PM) of intracardiac signals. Background Art

[0002] Cardiac mapping techniques using reference signals have been previously reported in the patent literature. For example, U.S. Patent Application Publication 2017 / 0251942 describes an automatic method for determining local activation time (LAT) from at least three multi-channel cardiac electrogram signals, the multi-channel cardiac electrogram signals including a mapping channel and multiple reference channels. The method includes (a) storing cardiac channel signals, (b) using the mapping channel signals and a first reference channel signal to calculate LAT values ​​at multiple mapping channel locations, (c) monitoring the timing stability of the first reference channel signal, and (d) if the timing stability of the monitored signal drops below a stability standard, using the signal of a second reference channel to determine the LAT value. Despite the loss of timing stability, a substantial loss of LAT values ​​is avoided.

[0003] As another example, U.S. Pat. No. 11,213,235 describes a method comprising receiving (i) a plurality of electrocardiogram (ECG) signals acquired by a mapping catheter at a plurality of locations on the surface of a patient's heart, (ii) a reference ECG signal obtained from a reference catheter positioned at a nominal position in the patient's coronary sinus (CS), and (iii) a position signal indicating the position of the reference catheter in the CS. An electrophysiological (EP) map of at least a portion of the heart is calculated by timing-marking the ECG signal relative to the reference ECG signal. Based on the position signal, a displacement of the reference catheter from the nominal position in the CS is estimated, the displacement distorting the timing marking. The estimated displacement is used to mitigate distortion in the EP map.

[0004] U.S. Patent No. 11,071,486 describes how to use catheter-mounted itinerant electrodes rather than fixed (e.g., coronary sinus) electrodes to map cardiac activation timing. The itinerant electrodes are used to measure an initial electrophysiological signal at an initial cardiac location as a reference signal, which is defined as a reference signal. Local activation times at other cardiac locations that are also measured using the catheter-mounted itinerant electrodes are determined relative to the reference signal. The stability of the reference signal can be monitored, such as by comparing the activation rate or cycle length between the instantaneously measured electrophysiological signal and the initial electrophysiological signal. Small differences between the two (e.g., less than about 5%) can be compensated, however larger differences may result in redefining the reference signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] 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:

[0006] Figure 1 is a schematic illustration of a catheter-based electrophysiological (EP) sensing system according to an example of the present disclosure;

[0007] Figure 2 is a schematic illustration of the change in position of a coronary sinus (CS) catheter within a CS according to an example of the present disclosure;

[0008] Figure 3A and Figure 3B is a set of graphs showing actual intracardiac ECG (IC-ECG) signals according to some examples of the present disclosure, (3A) associated with a template pattern of the IC-ECG signal, and (3B) not associated with the template pattern of the IC-ECG signal, the signal being generated by a CS placed in Figure 1 The electrodes of the catheter are collected; and

[0009] Figure 4 is a flow chart schematically illustrating a method of location-based pattern matching of CS IC-ECG signals according to an example of the present disclosure. DETAILED DESCRIPTION

[0010] Overview

[0011] During electrophysiological (EP) mapping, a physician may wish to capture an arrhythmic event and determine its spatial distribution of rhythm in a cardiac chamber. To this end, the physician performs EP mapping of the cardiac chamber using an EP mapping catheter. However, the local nature of EP acquisition does not allow the physician or the processor of the EP mapping system to determine the relevance of a given EP signal, because the relevance depends on whether the arrhythmia is actually occurring or has ceased when the signal is acquired.

[0012] To ensure that diagnostic EP signals are acquired during the occurrence of an arrhythmia, a physician may use a reference catheter, such as a coronary sinus (CS) catheter, to pre-capture a template of an arrhythmogenic coronary sinus electrophysiology (CS-EP) signal (also known as an "intracardiac electrogram (IC-ECG)") expressed during the occurrence of an arrhythmia. The processor or physician may then compare any newly acquired CS reference signals acquired during the EP acquisition period to the template in order to verify that the mapped EP signals are clinically relevant (i.e., acquired during the occurrence of an arrhythmia).

[0013] In this way, under the condition that there is a good correlation between the current IC-EP (e.g., IC-ECG) signal and the CS-EP (e.g., IC-ECG template), the EP signal (hereinafter referred to as "intracardiac electrophysiology (IC-EP) signal") acquired at a specific tissue location within the heart chamber to be mapped is accepted (e.g., for generating an EP map). As used in IC PM, this test, called pattern matching (PM), is a technique that acquires patterns from an IC catheter (primarily placed in the CS) rather than attempting to correlate ECG signals acquired from electrodes attached to the skin, because the former method obtains more relevant arrhythmogenic patterns.

[0014] One disadvantage of this approach is that the catheter in the CS tends to move over time. This movement causes the IC PM correlation score to drop to unusable correlation levels (in one example, to less than 75% after about half an hour). This drop in correlation causes the physician or system to waste time acquiring new patterns and creating new EP maps.

[0015] Examples of the disclosure described herein provide a technique for achieving more accurate IC pattern matching that is less prone to unexpected correlation score drops. The disclosed technique includes generating a pool of template IC patterns corresponding to different corresponding positions of a CS catheter. The pool is pre-saved for use whenever movement of the CS catheter is detected. To this end, a processor switches between pre-recorded IC patterns to identify a pattern recorded at a CS position that is closest to the current CS catheter position. Before using the identified pattern, the processor verifies its accuracy by running a pattern match (e.g., by comparing the correlation score between the actual pattern and the identified reference pattern to a predefined threshold PM score).

[0016] In one example, a method is therefore provided, which includes acquiring multiple sets of CS-EP signals using a first catheter in the CS of a patient's heart, while measuring multiple corresponding reference CS positions of the first catheter (e.g., the CS catheter defined above). One or more intracardiac electrophysiological (IC-EP) signals are acquired using a second catheter (e.g., the aforementioned mapping catheter) located in a cardiac chamber of the heart, while actual CS-EP signals are acquired using the first catheter, and the actual CS position of the first catheter is measured simultaneously. Using the reference CS positions, a reference CS-EP signal whose reference CS position is closest to the actual CS position of the first catheter is identified. A signal stability measure between the actual CS-EP signal and the identified reference CS-EP signal is estimated. Finally, if the signal stability measure is above a given threshold, the identified reference CS-EP is used to verify whether the one or more IC-EP signals acquired by the second catheter were acquired during the occurrence of an arrhythmia.

[0017] To acquire the CS catheter position, in one example, the CS catheter includes a magnetic sensor for measuring the CS catheter position. In another example, electrical position detection may be used to track the CS position of each mode acquired.

[0018] By introducing the disclosed feature structure, the user is less likely to need to reacquire the IC-ECG template pattern, which would require wasting time to build a new map with the new pattern. Therefore, an important benefit of this method is to reduce the duration of the EP mapping procedure.

[0019] The technique thus includes an initial recording phase in which, prior to an EP mapping session, the user is prompted to move the CS catheter in the CS vein during an arrhythmia to record a pattern set of CS-EP template signals according to the CS catheter position within the CS. As the CS catheter is moved, the disclosed algorithm saves the patterns and corresponding CS catheter positions in order to generate a pool of sub-pattern templates (i.e., patterns and corresponding positions). This phase typically takes between 10 and 30 seconds.

[0020] During EP mapping performed by an EP mapping catheter inserted into a target cardiac chamber, the latest position of the CS catheter is monitored, enabling selection of a relevant template from the pattern set. A subpattern is automatically matched to the nearest CS catheter position measured from the subpattern, thereby overcoming CS movement that causes a drop in correlation scores.

[0021] In one example, during EP mapping, the processor switches between stored template modes (within the group) to select the mode that best matches the actual CS catheter position. Switching can be initiated automatically based on tracking the movement of the CS catheter. Switching can also be triggered manually, such as based on the user identifying a degraded correlation score (e.g., the PM score drops below a predefined threshold). Alternatively, as described above, switching between sub-modes may not be available to the user, where switching to another position-based pattern match is only done automatically by the processor.

[0022] In some examples, during the initial recording phase, the acquired IC-ECG patterns are filtered using, for example, a filter based on local activation time (LAT), which runs in the background (e.g., not available in user preferences) to ensure that the same arrhythmia is being recorded. The filter rejects any IC-ECG pattern acquired when the LAT value on the reference signal does not match a "global" LAT value characteristic of an arrhythmia (such as atrial flutter) until a tolerance is reached.

[0023] Using a set of patterns rather than a single pattern actually acquires more data points because fewer data points are rejected due to correlation failure. Experimental observations have shown that during EP mapping, the acquired data point count increased by 60%, amounting to thousands of additional successfully acquired EP data points, meaning that with a multi-electrode catheter, it is possible to complete an EP map without a single correlation failure.

[0024] The provided method includes acquiring reference CS-EP signals, such as IC-ECG signals, using a plurality of electrodes of a first catheter located at different corresponding measured CS positions in the coronary sinus (CS) of a patient's heart to generate a reference CS signal set. One or more IC-EP signals are acquired using one or more electrodes of a second catheter located in a cardiac chamber of the heart, while the IC-EP signals are acquired using the first catheter to generate an actual CS reference signal at a corresponding actual CS position. A corresponding signal stability measure is estimated between the actual CS reference signal and the signals of the CS reference signal set acquired at the CS position closest to the actual CS position. If the signal stability measure is above a given threshold, an EP mapping data point is generated, for example, using one or more IC-EP signals acquired by the second catheter.

[0025] The signal stability measure can be an average of the stability measures for signals from multiple electrodes, or a minimum of the stability measures. For example, assuming a set of correlation levels are calculated for signals from a set of electrodes, the measure can be the average correlation level or the minimum correlation level in the set. If a correlation score or PM score is provided, the score can be the average score or the minimum score in a set of scores calculated for the set of electrodes.

[0026] 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.

[0027] System Description

[0028] Figure 1 is a schematic illustration of a catheter 21 based electrophysiological (EP) sensing system 20 according to an example of the present disclosure. Figure 1 Illustration 15 of 200 shows the general anatomy of the heart, and as can be seen, the right atrium collects deoxygenated blood from three sources, the superior vena cava (SVC), the inferior vena cava (IVC), and the SC which returns blood from the myocardium. In illustration 25, catheter 21 is inserted into CS 202 to collect IC-ECG signals which may indicate atrial flutter originating from either RA or LA.

[0029] The catheter 21 includes a deflectable tip section 40 mounted at the distal end of the shaft 22 of the catheter 21, wherein the deflectable tip section 40 includes a plurality of electrodes 50. In the example described herein, the physician 30 manipulates the sheath 23 of the catheter 21 within the RA using the catheter handle 32 in order to insert the deflectable tip section 40 into the CS 202 so that the deflectable tip section 40 is moved in a direction similar to that of the CS 202. Figure 2 As described in , the distal portion of electrode 50 overlaps with the LA of heart 26 to acquire EP signals originating from the LA, while the proximal portion of electrode 50 overlaps with the RA of heart 26 to acquire EP signals originating from the RA. The IC-ECG signal may be a unipolar signal measured between electrode 50 and surface electrodes 38, which are attached to the chest of patient 28 positioned on examination table 29 by wires passing through cable 37 in the exemplary system.

[0030] The proximal end of catheter 21 is connected to console 24, which includes interface circuitry 44. Electrodes 50 are connected by wires passing through shaft 22 to interface circuitry 44, where EP signals are received and processed (eg, digitized) and output to processor 41 in console 24 for analysis.

[0031] The processor 41 may further receive an electrical impedance signal measured between the electrode 50 and the surface electrode 38. A method for using the measured impedance to track the position of the electrode 50 is implemented in various medical applications, such as in the CARTO TM The present invention is implemented in a system and described in detail in U.S. Patent No. 8,456,182, which is assigned to the assignee of the present disclosure. This method is sometimes referred to as advanced catheter positioning (ACL). Console 24 drives display 27, which shows the tracked position and / or shape of deflectable tip segment 40 within heart 26. Various signals (such as EP signals) are stored in memory 46.

[0032] In some examples, the system 20 also includes a magnetic positioning system to magnetically track the position of the catheter 21 within the CS 202. To this end, the console 24 also includes a drive circuit 34 configured to drive the fixed magnetic field generator 36. As further seen, the CS catheter 21 is equipped with a magnetic sensor 52 at the moving deflectable end portion 40. During navigation of the deflectable end portion 40, the console 24 receives a position signal from the magnetic sensor 52 in response to the magnetic field from the fixed external field generator 36, and the processor calculates the end position in the coordinate system of the fixed magnetic field generator 36. Position sensing methods using external magnetic fields are implemented in various medical applications, such as in the CARTO TMThe method is implemented in the system, which is described in detail in U.S. Patents 6,618,612 and 6,332,089, PCT Patent Publication WO 96 / 05768, and U.S. Patent Application Publications 2002 / 0065455, 2003 / 0120150 and 2004 / 0068178, the disclosures of which are incorporated herein by reference.

[0033] The processor 41 shown included in the console 24 is typically a general purpose computer with a suitable front end and interface circuitry 44 for receiving signals from the catheter 21 in the left atrium of the heart 26 and for controlling other components of the system 20. The processor 41 typically includes software in a memory 48 of the system 20 that is 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 41 runs the software disclosed herein and included in the system 20. Figure 4 , which enables the processor 41 to perform the disclosed steps, as further described below.

[0034] Movement of the CS catheter within the CS

[0035] Figure 2 2 is a schematic illustration of a change in position 232 of a coronary sinus (CS) catheter 21 within a CS 202 according to an example of the present disclosure. Figure 2 , the deflectable tip portion 40 is seen shifting (232) between two positions (eg, a previous position 242 and a new actual position 252).

[0036] Such a position change may disqualify the use of the IC-ECG mode because its PM score drops below a threshold. However, using the disclosed techniques, when a new position 252 is measured, the processor switches between the stored template modes (within the group) to select a mode based on the mode that most closely matches the actual CS catheter position 252.

[0037] Correlated and uncorrelated IC-ECG signals acquired by CS catheter

[0038] The processor 41 can calculate a correlation score for an IC-ECG signal acquired by a catheter 21 located in the CS using a method disclosed in U.S. Patent Application Publication 2021 / 0169359 assigned to the assignee of the present application, wherein the processor applies a window of interest (WOI) to the IC-ECG signal representing the entire cycle length of a single heartbeat. A pattern of interest (POI) is selected to include a portion of the WOI corresponding to an arrhythmia activation. A template POI is generated, which represents the arrhythmia activation. Subsequent electrical activity is received, weights are applied, and the subsequent electrical activity is compared to the template POI. A correlation score (also referred to herein as a "PM score") is generated.

[0039] Figure 3A and Figure 3B is a set of graphs according to some examples of the present disclosure, which shows an actual IC-ECG signal 204 associated with a template pattern of a CS-EP signal 200 as (3A), and an actual CS-EP signal 304 not associated with another template pattern of the IC-ECG signal 300 as (3B), wherein all signals (200, 204, 300, 304) are generated by placing a CS 202 in Figure 1 The electrodes 50 of the CS catheter 21 are collected.

[0040] Actual CS-EP signals 204 and 304 are acquired during EP mapping. A correlation level, which may be an average or minimum value for all electrodes, is provided (175) on the displayed graph. As shown, the calculated correlation level or correlation score is Figure 3A The difference between the actual CS signal and the reference signal is very high (e.g., 0.9), but Figure 3B The ratio between these signals in is very low (e.g., 0.2).

[0041] exist Figure 3B The lack of correlation seen in may occur due to movement of the catheter 21, or due to an arrhythmia not occurring when the signal was acquired. To overcome low correlation due to CS catheter movement, the processor switches between stored template patterns (within the group) to select a pattern based on the pattern that most closely matches the actual CS catheter position, such as Figure 4 As described in .

[0042] Position-based pattern matching method for CS IC-ECG signals

[0043] Figure 4 is a flow chart schematically illustrating a method of position-based pattern matching of CS-EP (eg, CS IC-ECG) signals according to examples of the present disclosure. According to the presented example, the algorithm is divided into a recording phase 401 and an EP mapping phase 411 .

[0044] The recording phase 401 executes a process beginning with a CS catheter movement step 402, wherein the physician 30 moves the deflectable tip portion 40 of the catheter 21 within the CS 202, such as Figure 1 As seen in , CS-EP patterns at tracking locations, such as pattern 200 or 300, are recorded one at a time.

[0045] Meanwhile, at LAT filtering step 404, processor 41 runs a LAT filter to verify that the CS-EP pattern was recorded while the arrhythmia under study was active.

[0046] At a check step 406 , the processor checks whether the same arrhythmia is indeed recorded. If the answer is no, as derived, for example, from the calculated ALT value, the processor discards the irrelevant IC-ECG pattern at a reference pattern discard step 408 .

[0047] If the answer is yes, the processor 41 saves ( 410 ) the IC-ECG pattern and similar qualified patterns recorded and reviewed as the catheter was moved within the CS 202 .

[0048] At a mode group aggregation step 412, the processor aggregates eligible CS-EP modes (ie, CS IC-ECG modes) and corresponding locations in a folder for use during a subsequent EP mapping session.

[0049] The ECG mapping phase 401 performs a process beginning with a CS catheter movement step 402, in which the physician 30 moves the deflectable tip portion 40 of the catheter 21 within the CS 202, such as Figure 1 As seen in , IC-ECG patterns, such as pattern 200 or 300, are recorded at the tracking locations one at a time.

[0050] When a physician uses an EP mapping catheter (not shown) such as The EP mapping phase 411 executes the process starting from the EP signal acquisition step 422 when the IC-ECG signal at the cardiac chamber is acquired by using a catheter) and the actual CS pattern is acquired at the same time.

[0051] Next, the processor checks whether the CS catheter was stable during acquisition at a CS catheter position check step 423. The actual position may be determined using the magnetic or electrical detection methods described above.

[0052] If the answer is "yes", then at the correlation score check step 424, the processor 41 calculates the PM score of the correlation between the current template of the CS-EP signal in use and the actual CS pattern acquired in step 422 and applies the aforementioned method to the PM score and compares it with a threshold value (e.g., threshold value = 0.75). If the PM score is above the threshold value, the processor saves the EP signal at the EP signal save step 426. If the PM score is below the threshold value, the processor 41 discards the EP signal at the EP signal discard step 425.

[0053] If the answer to step 424 is "no," meaning the CS catheter position has changed, at a reference IC mode selection step 428, processor 41 switches between stored template modes (within the group) to select a mode based on the most recent actual position of the CS catheter.

[0054] At the second correlation score check step 430, the processor 41 calculates the PM score of the correlation between the template of the CS-EP signal selected in step 428 and the actual CS pattern acquired in step 422 and applies the aforementioned method to the PM score and compares it with a threshold. If the PM score is now above the threshold, the processor saves the EP signal at an EP signal save step 432. If the PM score is still below the threshold, the processor 41 discards the EP signal at an EP signal discard step 434. In any case, while mapping, the process returns to step 422 to acquire a new EP signal.

[0055] Figure 4 The flowchart of is simplified for clarity and is given by way of example. In practice, there may be additional steps, such as notification and presentation of the EP map in construction.

[0056] Example

[0057] Example 1

[0058] A method includes, during an arrhythmia occurrence, using a first catheter (21) in a coronary sinus (CS) (202) of a heart (26) of a patient (28) to collect multiple sets of reference coronary sinus electrophysiological (CS-EP) signals (200, 300), while measuring multiple corresponding reference CS positions of the first catheter (21). Using a second catheter located in a cardiac chamber of the heart to collect one or more intracardiac electrophysiological (IC-EP) signals, while using the first catheter to collect actual CS-EP signals (204, 304), and while measuring the actual CS position of the first catheter. Using the reference CS position to identify a reference CS-EP signal whose reference CS position is closest to the actual CS position of the first catheter (21). Estimating a signal stability measure between the actual CS-EP signal and the identified reference CS-EP signal. If the signal stability measure is above a given threshold, using the identified reference CS-EP to verify whether the one or more IC-EP signals collected by the second catheter were collected during the arrhythmia occurrence.

[0059] Example 2

[0060] A method according to Example 1, and including, upon verifying that the one or more IC-EP signals were acquired during the arrhythmia, using the one or more IC-EP signals to generate one or more data points of an EP map of cardiac tissue during the arrhythmia.

[0061] Example 3

[0062] The method according to any one of embodiments 1 and 2, wherein estimating the signal stability measure comprises estimating a correlation level between the actual CS-EP signal (204, 304) and the identified reference CS-EP signal.

[0063] Example 4

[0064] The method according to any one of embodiments 1 to 3, wherein estimating the signal stability measure includes calculating a correlation score from the correlation level, and comparing the correlation score to a predefined threshold score.

[0065] Example 5

[0066] A method according to any one of embodiments 1 to 4, wherein the first catheter (21) includes a distal end, the distal end including a linear array of electrodes (50).

[0067] Example 6

[0068] A method according to any one of embodiments 1 to 5, wherein measuring the CS position comprises acquiring a position signal using one or more electrodes (50) of the first catheter (21), and analyzing the position signal.

[0069] Example 7

[0070] A method according to any one of embodiments 1 to 6, wherein measuring the CS position includes acquiring a position signal using a magnetic sensor (52) mounted at the distal end of the first catheter (21), and analyzing the position signal.

[0071] Example 8

[0072] The method according to any one of embodiments 1 to 7, wherein the IC EP signal is an IC electrocardiogram (ECG) signal.

[0073] Example 9

[0074] A system (20) includes a first catheter (21), a second catheter, and a processor (41). The first catheter is configured to be located in a coronary sinus (CS) (202) of a heart (26) of a patient (28) and to collect multiple sets of reference coronary sinus electrophysiological (CS-EP) signals (200, 300) during arrhythmia, while simultaneously measuring multiple corresponding reference CS positions of the first catheter. The second catheter is configured to be located in a cardiac chamber of the heart and to collect one or more intracardiac electrophysiological (IC-EP) signals, while simultaneously collecting actual CS-EP signals (204, 304) using the first catheter, and simultaneously measuring the actual CS position of the first catheter. The processor (41) is configured to (a) use the reference CS position to identify a reference CS-EP signal whose reference CS position is closest to the actual CS position of the first catheter, (b) estimate a signal stability measure between the actual CS-EP signal (204, 304) and the identified reference CS-EP signal, and (c) if the signal stability measure is above a given threshold, use the identified reference CS-EP to verify whether one or more IC-EP signals acquired by the second catheter were acquired during the occurrence of an arrhythmia.

[0075] 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 and their variations and modifications, which will occur to a person skilled in the art when reading the above description and which are not disclosed in the prior art. The documents incorporated by reference into this patent application are considered an integral part of this application, unless any term defined in these incorporated documents conflicts with the definition explicitly or implicitly given in this specification, in which case only the definition in this specification shall be considered.

Claims

1. A method, include: During the occurrence of arrhythmia, a plurality of reference coronary sinus electrophysiological (CS-EP) signals are acquired using a first catheter in the coronary sinus (CS) of the patient's heart, and a plurality of corresponding reference CS positions of the first catheter are measured simultaneously; Acquire one or more intracardiac electrophysiological (IC-EP) signals using a second catheter located in a cardiac chamber of the heart, acquire actual CS-EP signals using the first catheter, and simultaneously measure an actual CS position of the first catheter; identifying, using the reference CS position, a reference CS-EP signal whose reference CS position is closest to the actual CS position of the first catheter; estimating a signal stability measure between the actual CS-EP signal and the identified reference CS-EP signal; as well as If the signal stability measure is above a given threshold, the identified reference CS-EP is used to verify whether the one or more IC-EP signals acquired by the second catheter were acquired during the occurrence of the arrhythmia.

2. The method of claim 1 , and comprising, upon verifying that the one or more IC-EP signals were acquired during the arrhythmia, using the one or more IC-EP signals to generate one or more data points of an EP map of cardiac tissue during the arrhythmia.

3. The method according to claim 1, in, Estimating the signal stability measure includes estimating a level of correlation between the actual CS-EP signal and the identified reference CS-EP signal.

4. The method according to claim 3, in, Estimating the signal stability measure includes calculating a correlation score from the correlation level and comparing the correlation score to a predefined threshold score.

5. The method according to claim 1, in, The first catheter includes a distal end including a linear array of electrodes.

6. The method according to claim 1, in, Measuring the CS position includes acquiring a position signal using one or more electrodes of the first catheter, and analyzing the position signal.

7. The method according to claim 1, in, Measuring the CS position includes acquiring a position signal using a magnetic sensor mounted at a distal end of the first catheter, and analyzing the position signal.

8. The method according to claim 1, in, The IC-EP signal is an IC electrocardiogram (ECG) signal.

9. A system, include: a first catheter configured to be positioned in a coronary sinus (CS) of a patient's heart and to acquire a plurality of sets of reference coronary sinus electrophysiological (CS-EP) signals during an arrhythmia event while simultaneously measuring a plurality of corresponding reference CS positions of the first catheter; a second catheter configured to be located in a cardiac chamber of the heart and to acquire one or more intracardiac electrophysiological (IC-EP) signals while acquiring actual CS-EP signals with the first catheter and simultaneously measuring an actual CS position of the first catheter; and A processor, the processor being configured to: identifying, using the reference CS position, a reference CS-EP signal whose reference CS position is closest to the actual CS position of the first catheter; estimating a signal stability measure between the actual CS-EP signal and the identified reference CS-EP signal; as well as If the signal stability measure is above a given threshold, the identified reference CS-EP is used to verify whether the one or more IC-EP signals acquired by the second catheter were acquired during the occurrence of the arrhythmia.

10. The system according to claim 9, in, The processor is further configured to, upon verifying that the one or more IC-EP signals were acquired during the arrhythmia, use the one or more IC-EP signals to generate one or more data points of an EP map of cardiac tissue during the arrhythmia.

11. The system according to claim 9, in, The processor is configured to estimate the signal stability measure by estimating a correlation level between the actual CS-EP signal and the identified reference CS-EP signal.

12. The system according to claim 11, in, The processor is further configured to estimate the signal stability measure by calculating a correlation score from the correlation level and comparing the correlation score to a predefined threshold score.

13. The system according to claim 10, in, The first catheter includes a distal end including a linear array of electrodes.

14. The system according to claim 10, in, Measuring the CS position includes acquiring a position signal using one or more electrodes of the first catheter, and analyzing the position signal.

15. The system according to claim 10, in, Measuring the CS position includes acquiring a position signal using a magnetic sensor mounted at a distal end of the first catheter, and analyzing the position signal.

16. The system according to claim 10, in, The IC-EP signal is an IC electrocardiogram (ECG) signal.

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