Bystander atrium detection using coronary sinus (CS) signals

Abstract

The atrial flutter identification method includes placing a catheter with multiple electrodes in the coronary sinus (CS) of a patient's heart such that some of the electrodes overlie the left atrium (LA) of the heart and some of the electrodes overlie the right atrium (RA) of the heart. Intracardiac (IC) electrophysiological (EP) signals are acquired using the electrodes. Respective signal stability measures are estimated over the signals acquired by the electrodes overlying the LA and over the signals acquired by the electrodes overlying the RA. When one of the signal stability measures is above a first threshold while the other of the signal stability measures is below a second threshold, the atrium corresponding to the highest of the signal stability measures is indicated as the source of atrial flutter.

Description

[Technical field]

[0001] The present disclosure relates generally to electrophysiological (EP) sensing using catheters, and more particularly to EP sensing of atrial flutter using a catheter placed in the coronary sinus (CS). [Background technology]

[0002] Cardiac diagnostic and / or therapeutic techniques involving placement of a catheter in the coronary sinus have previously been proposed in the patent literature. For example, U.S. Patent Application Publication No. 2012 / 0172867 describes a system and method for treating arrhythmias in the heart. The system includes a position sensor in contact with a portion of cardiac tissue, and analyzed changes in position represent motion of that tissue. The system is configured to generate an indicator of a cardiac characteristic affected by delivery of ablation energy to the cardiac tissue in response to movement of the sensor over a period of time. In this manner, the efficacy and safety of cardiac tissue ablation for treatment of arrhythmias can be evaluated and post-ablation treatment regimes can be determined. In an exemplary embodiment, a coronary sinus (CS) catheter for use in collecting EP data associated with the heart can also be provided to enable generation of an image of the cardiac surface geometry and associated EP data. Because the coronary sinus is a relatively stable location, the CS catheter may also provide a position reference against which position measurements for the mapping catheter are compared to compensate for cardiac motion. [Brief description of the drawings]

[0003] The present disclosure will become more fully understood from the following detailed description of the embodiments thereof, taken in conjunction with the drawings, in which: [Figure 1] FIG. 1 is a schematic, depiction of a catheter-based electrophysiological (EP) sensing system according to an example of the present disclosure. [Diagram 2] 2 is a schematic, depiction diagram of the catheter of FIG. 1 positioned in the coronary sinus (CS), according to an example of the present disclosure. [Figure 3A]2 is a graph of a set of intracardiac EP signals from two cardiac cycles acquired by electrodes of the catheter of FIG. 1 placed in the CS, according to an example of the present disclosure. [Figure 3B] 2 is a graph of a set of intracardiac EP signals from two cardiac cycles acquired by electrodes of the catheter of FIG. 1 placed in the CS, according to an example of the present disclosure. [Figure 4] 1 is a flow chart that generally illustrates a method for identifying the atrium of origin of atrial flutter, according to an example of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0004] overview Atrial flutter is an arrhythmia that occurs in the atria of the heart. Atrial flutter is usually associated with a tachycardia when it first occurs and falls under the category of supraventricular tachycardia (SVT). This rhythm occurs most frequently in individuals with cardiovascular disease or diabetes, but may occur spontaneously in people whose hearts are otherwise normal. Atrial flutter is typically not a stable rhythm and often deteriorates into atrial fibrillation (AF). Thus, treatment of atrial flutter is desirable.

[0005] Atrial flutter is usually found to be caused by a single reentrant wavefront in the left atrium (LA) or right atrium (RA), which is usually characterized by continuous circular activation of the atria around an anatomical obstruction. Because of the reentrant nature of atrial flutter, it is often possible to ablate the circuit causing atrial flutter. This is typically done in an electrophysiology operating room by creating a ridge of scar tissue across the path of the circuit causing atrial flutter. Ablation of the isthmus as described above is a common treatment for typical atrial flutter.

[0006] When initially diagnosing flutter, it is often not clear to the physician whether the flutter originates from the left or right atrium. The origin of the flutter can be determined after EP mapping of both the left and right atria, which is time consuming and may expose patients with RA flutter to the risk of puncturing the septum while navigating to the LA for mapping. Furthermore, if the flutter is within the RA, it may not be necessary to map the LA.

[0007] Examples of the disclosure described herein provide techniques for acquiring and analyzing CS signals captured with a CS catheter to identify the atrium that is most likely the source of the flutter. The CS signal may be a unipolar intracardiac (IC) electrogram (EGM) signal. The CS catheter has multiple electrodes and is positioned so that the electrodes extend across the left and right atria, including a separate electrode group extending across each atrium.

[0008] Using a processor and algorithm, the repeatability of each group of IC signals in time (e.g., between templates of reference signals acquired during periods of arrhythmia to serve as reference arrhythmogenic signals for EP mapping) may be independently monitored and compared such that mapping occurs during periods when the heart exhibits arrhythmia, thereby providing clinical value to the procedure. The atrium responsible for the flutter is expected to exhibit an IC signal similar to the template, while the IC EGM signal from the bystander atrium is expected to differ from the reference arrhythmogenic signal.

[0009] In other words, a CS catheter with multiple electrodes is positioned such that some of the electrodes overlie the LA of the heart and some of the electrodes overlie the RA of the heart. Using the EP signal from the CS catheter, the processor estimates respective signal stability measures over the signals acquired by the electrodes overlying the LA and over the signals acquired by the electrodes overlying the RA. Thus, portions of the CS signal, either distal or proximal, that have high signal stability (e.g., are highly correlated) are those that are likely to originate from arrhythmogenic tissue atria.

[0010] Furthermore, when the physician observes the CS signal, there is instability of the IC CS signal in the portion of the electrode that overlaps the bystander atrium, which is due to the unstable state of the passage of activation between the heart chambers. At the same time (i.e., while the arrhythmia is active), the portion of the signal acquired by the CS electrode that overlaps the arrhythmogenic atrium shows a high degree of reproducibility (e.g., stability). Thus, the physician can know with a high degree of confidence which atrium has abnormal tissue even before inserting the mapping catheter.

[0011] Typically, the processor is programmed with software that contains specific algorithms that enable the processor to perform each of the processor-related steps and functions outlined above.

[0012] System Description FIG 1 is a schematic depiction of a catheter-based 21 electrophysiological sensing system 20, according to one embodiment of the present invention. Inset 15 of FIG 1 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 CS, which returns blood from the myocardium. Inset 25, catheter 21 is inserted into CS 202 to collect IC EGM signals that may be indicative of atrial flutter originating from either the RA or LA.

[0013] The system 21 includes a deflectable tip section 40 mounted on the distal end of the shaft 22 of the catheter 21 having a deflectable tip section 40 including a plurality of electrodes 50. In the example described herein, the deflectable tip section 40 is inserted into the CS 202 such that a distal portion of the electrode 50 overlies the LA of the heart 26 to acquire EP signals emanating from the LA and a proximal portion of the electrode 50 overlies the RA of the heart 26 to acquire EP signals emanating from the RA, as described in FIG. 2. The IC EGM signal may be a unipolar signal measured between the electrode 50 and the surface electrode 38, as seen in the exemplary system attached by a wire extending through the cable 37 to the chest of the patient 28 lying on the table 29.

[0014] The proximal end of catheter 21 is connected to a control console 24 that includes an interface circuit 44. Electrodes 50 are connected by wires that extend through shaft 22's interface circuit 44 where the EP signals are received, processed (e.g., digitized), and output to a processor 41 within console 24 for analysis.

[0015] The processor 41 may further receive electrical impedance signals measured between the electrodes 50 and the surface electrodes 38. A method for tracking the position of the electrodes 50 using the measured impedance has been implemented in various medical applications, for example in the CARTO™ system manufactured by Biosense-Webster (Irvine, Calif.) and described in detail in U.S. Pat. No. 8,456,182, assigned to the assignee of the present disclosure. The method may be referred to as Advanced Catheter Location (ACL). The console 24 drives a display 27 that shows the tracked position and / or shape of the deflectable tip portion 40 within the heart 26. Various signals, such as the EP signal, are stored in a memory 46.

[0016] The processor 41 shown included in the control console 24 is typically a general-purpose computer with 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 the other components of the system 20. The processor 41 typically includes software in the memory 46 of the system 20 that is programmed to perform the functions described herein. The software may be downloaded to the computer in electronic form, for example, over a network, or alternatively or additionally may be provided and / or stored on a non-transitory tangible medium, such as a magnetic, optical, or electronic memory. In particular, the processor 41 executes the dedicated algorithms disclosed herein and included in FIG. 4 that enable the processor 41 to perform the steps of the present disclosure, as described further below.

[0017] Bystander atrium detection using CS signals 2 is a schematic depiction of the catheter 21 of FIG. 1 positioned within the coronary sinus (CS) according to one example of the present disclosure. As can be seen, a distal portion 501 of the electrode 50 overlies the LA and a proximal portion 502 of the electrode 50 overlies the RA. The electrodes belonging to the distal portion 501 acquire local IC signals primarily associated with the LA tissue, while the electrodes belonging to the proximal portion 502 acquire local IC signals primarily associated with the LA tissue.

[0018] 3A and 3B are graphs of a set of IC EGM signals from two cardiac cycles acquired with electrodes of the catheter of FIG. 1 placed in the CS, according to one example of the present disclosure.

[0019] In Fig. 3A, the distal portion 304 of the electrode overlaps the LA, while the proximal portion 305 of the electrode overlaps the RA. As can be seen, the signal from the distal portion 304 is highly uncorrelated (e.g., different) when comparing the template arrhythmogenic CS signal with the newly acquired one. Meanwhile, the signal from the proximal portion 304 is highly correlated between the two cardiac cycles. As mentioned above, such a case is highly indicative of the occurrence of atrial flutter in the RA.

[0020] As can be seen in Figure 3B, which shows results from another patient, the signal from the distal portion 307 is highly uncorrelated (e.g., different) when comparing the template arrhythmogenic CS signal with the newly acquired one, whereas the signal from the proximal portion 306 is highly correlated (e.g., similar) when comparing the two cardiac cycles, strongly indicating atrial flutter originating from the LA.

[0021] The processor 41 may quantify the above observation by calculating separate correlation scores for the signals from the distal and proximal portions. In one example, stability may be determined based on such correlation scores. To this end, the method disclosed in commonly assigned U.S. Patent Application Publication No. 2021 / 0169359 can be used, in which the processor applies a window of interest (WOI) to an IC EGM signal representing the entire cycle length of one heartbeat. A pattern of interest (POI) is selected to include a portion of the WOI that corresponds to arrhythmia activation. A template POI is generated to represent arrhythmia activation. Subsequent electrical activity is received, weights are applied, and the subsequent electrical activity is compared to the template POI. A correlation score is generated.

[0022] In the present disclosure, such correlation scores for the group of electrodes associated with the left atrium are compared to the correlation scores for the group of electrodes associated with the right atrium. Based on the comparison, the atrium causing the flutter can be identified.

[0023] For example, the processor 41 may compare each portion of the correlation score to a predetermined score and, based on the comparison, inform the user which atrium is responsible for the atrial flutter.

[0024] The above description refers to the use of correlations and correlation scores as examples, in alternative examples, the processor 41 may use any other suitable signal stability measure to quantify the signal stability of the electrodes associated with the right atrium versus the electrodes associated with the left atrium.

[0025] A method for detecting bystander atria using CS signals 4 is a flow chart that illustrates a schematic of a method for identifying the atrium of origin of atrial flutter according to an example of the present disclosure. The algorithm executes a process that, according to the example presented, starts with a catheter placement step 402, where the physician 30 inserts, navigates and places the catheter inside the CS 202, with the distal portion 501 and the proximal portion 502 of the electrode 50 split to cover the LA and RA, respectively, as seen in FIG. 2. The physician 28 utilizes a manipulator / handle 32 connected to the sheath 23, whose shaft 22 is located to control the catheter 21.

[0026] Next, in an EP signal acquisition step 404, physician 30 acquires IC EGM signals at the SC using catheter 21, as described above.

[0027] In a correlation score calculation step 406, the processor 41 applies the methods described above to score the repeatability of the IC EGMS signals acquired by the distal and proximal portions of the electrodes 50 in comparison with the template arrhythmogenic signal.

[0028] In a score comparison step 408, the processor identifies one atrium having a low correlation score and the other atrium having a high correlation score.

[0029] Based on this comparison, processor 41 notifies the physician, at a notification step 410, that the atrium having a high correlation score is the atrium identified as the source of atrial flutter.

[0030] For example, if in step 408 above, one of the signal stability measures is above a first threshold while the other signal stability measure is below a second threshold, the processor in step 410 indicates the atrium corresponding to the highest signal stability measure as the source of atrial flutter.

[0031] The exemplary flow chart shown in Figure 4 has been chosen purely for purposes of conceptual clarity. In alternative examples, additional steps may be performed, such as processor 41 acquiring a position signal using electrodes 50, adjusting catheter placement and / or verifying catheter placement stability based on the position signal, and a user visually inspecting the signal on a display. EXAMPLES

[0032] Example 1 The atrial flutter identification method includes positioning a catheter (21) with multiple electrodes (50) in a coronary sinus (CS) (202) of a heart (26) of a patient (28) such that some of the electrodes (50) overlie the left atrium (LA) of the heart and some of the electrodes (50) overlie the right atrium (RA) of the heart. Intracardiac (IC) electrophysiological (EP) signals are acquired with the electrodes (50). Respective signal stability measures are estimated over the signals acquired by the electrodes overlying the LA and over the signals acquired by the electrodes overlying the RA. When one of the signal stability measures is above a first threshold while the other of the signal stability measures is below a second threshold, the atrium corresponding to the highest of the signal stability measures is indicated as a source of atrial flutter.

[0033] Example 2 2. The method of claim 1, wherein the signal stability measure comprises a correlation level to a respective reference IC signal.

[0034] Example 3 3. The method of any of claims 1 and 2, wherein the reference IC signal is acquired during an arrhythmia period of the heart (26).

[0035] Example 4 The method according to any one of the preceding claims, wherein the reference IC signal is a template signal.

[0036] Example 5 The method according to any one of the preceding embodiments, wherein the reference IC signal is acquired during a previous cardiac cycle, and a correlation level below a second threshold indicates instability of the IC signal between cardiac cycles.

[0037] Example 6 The method of any one of Examples 1 to 5, wherein the electrodes (50) are arranged in a linear array along the distal end of the catheter.

[0038] Example 7 The method according to any one of Examples 1 to 6, comprising acquiring a position signal using an electrode (50) and, based on the position signal, adjusting the positioning of the catheter (21) and / or verifying the stability of the catheter positioning.

[0039] Example 8 The method according to any of Examples 1-7, wherein the IC EP signal is an IC electrogram (EGM) signal.

[0040] Example 9 The atrial flutter discrimination system includes a catheter 21 and a processor 41. The catheter 21 includes a plurality of electrodes 50, the catheter configured to be positioned within a coronary sinus (CS) 202 of a heart 26 of a patient 28 such that some of the electrodes overlie a left atrium (LA) of the heart and some of the electrodes overlie a right atrium (RA) of the heart. The processor is configured to (i) acquire intracardiac (IC) electrophysiological (EP) signals using the electrodes 50, (ii) estimate respective signal stability measures for the signals acquired by the electrodes overlying the LA and the signals acquired by the electrodes overlying the RA, and (iii) indicate the atrium corresponding to the highest of the signal stability measures as a source of atrial flutter when one of the signal stability measures is above a first threshold while the other of the signal stability measures is below a second threshold.

[0041] It will be understood that the above described embodiments are given by way of example, and the present disclosure is not limited to what has been particularly shown and described herein above. Rather, the scope of the present disclosure includes both combinations and subcombinations of the various features described above, as well as variations and modifications thereof that would occur to a person skilled in the art upon reading the foregoing description and that are not disclosed in the prior art. Documents incorporated into this patent application by reference shall be considered as an integral part of this application, provided that, to the extent that any term is defined in these incorporated documents in a manner that is inconsistent with the definition expressly or implicitly made herein, only the definition in this specification shall be considered.

[0042] [Embodiment] (1) A method for identifying atrial flutter, the method comprising: positioning a catheter comprising a plurality of electrodes within a coronary sinus (CS) of a patient's heart such that some of the electrodes overlie a left atrium (LA) of the heart and some of the electrodes overlie a right atrium (RA) of the heart; acquiring an intracardiac (IC) electrophysiological (EP) signal using said electrodes; estimating respective signal stability measures across the signals acquired by the electrodes overlapping the LA and across the signals acquired by the electrodes overlapping the RA; and indicating the atrium corresponding to the highest of the signal stability measures as a source of atrial flutter when one of the signal stability measures is above a first threshold while the other of the signal stability measures is below a second threshold. (2) The method of embodiment 1, wherein the signal stability measures include correlation levels to respective reference IC signals. (3) The method of embodiment 2, wherein the reference IC signal is acquired during an arrhythmia period of the heart. (4) The method of claim 2, wherein the reference IC signal is a template signal. (5) The method of embodiment 2, wherein the reference IC signal was acquired during a previous cardiac cycle, and a correlation level below the second threshold indicates instability of the IC signal between cardiac cycles.

[0043] (6) The method of embodiment 1, wherein the electrodes are arranged in a linear array along the distal end of the catheter. (7) The method of embodiment 1, comprising obtaining a position signal using the electrodes, and performing one or both of adjusting the positioning of the catheter and verifying the stability of the positioning of the catheter based on the position signal. (8) The method of embodiment 1, wherein the IC EP signal is an IC electrogram (EGM) signal. (9) An atrial flutter discrimination system, comprising: a catheter comprising a plurality of electrodes, the catheter configured to be positioned within a coronary sinus (CS) of a patient's heart such that some of the electrodes overlie a left atrium (LA) of the heart and some of the electrodes overlie a right atrium (RA) of the heart; a processor, the processor comprising: acquiring an intracardiac (IC) electrophysiological (EP) signal using said electrodes; estimating respective signal stability measures across the signals acquired by the electrodes overlapping the LA and across the signals acquired by the electrodes overlapping the RA; and when one of the signal stability measures is above a first threshold while the other of the signal stability measures is below a second threshold, the atrium corresponding to the highest of the signal stability measures is indicated as a source of atrial flutter. (10) The system of embodiment 9, wherein the signal stability measures include a correlation level to a respective reference IC signal.

[0044] (11) The system of embodiment 10, wherein the reference IC signal is acquired during an arrhythmia period of the heart. (12) The system of embodiment 10, wherein the reference IC signal is a template signal. (13) The system of embodiment 10, wherein the reference IC signal was acquired during a previous cardiac cycle, and a correlation level below the second threshold indicates instability of the IC signal between cardiac cycles. (14) The system of embodiment 9, wherein the electrodes are arranged in a linear array along the distal end of the catheter. (15) The system of claim 9, wherein the processor is further configured to obtain a position signal using the electrodes and, based on the position signal, instruct the processor to perform one or both of an adjustment of the catheter placement and a verification of the stability of the catheter placement.

[0045] (16) The system described in embodiment 9, wherein the IC EP signal is an IC electrogram (EGM) signal.

Claims

1. 1. An atrial flutter discrimination system comprising: a catheter comprising a plurality of electrodes configured to be positioned within a coronary sinus (CS) of a patient's heart such that some of the electrodes overlie a left atrium (LA) of the heart and some of the electrodes overlie a right atrium (RA) of the heart; a processor, the processor comprising: acquiring an intracardiac (IC) electrophysiological (EP) signal using said electrodes; estimating respective signal stability measures across the signals acquired by the electrodes overlapping the LA and across the signals acquired by the electrodes overlapping the RA; and when one of the signal stability measures is above a first threshold while the other of the signal stability measures is below a second threshold, the atrium corresponding to the highest of the signal stability measures is indicated as a source of atrial flutter.

2. The system of claim 1 , wherein the signal stability measures include a correlation level to a respective reference IC signal.

3. The system of claim 2 , wherein the reference IC signal is obtained during a period of arrhythmia of the heart.

4. The system of claim 2 , wherein the reference IC signal is a template signal.

5. The system of claim 2 , wherein the reference IC signal was acquired during a previous cardiac cycle, and a correlation level below the second threshold indicates instability of the IC signal between cardiac cycles.

6. The system of claim 1 , wherein the electrodes are arranged in a linear array along a distal end of the catheter.

7. 2. The system of claim 1, wherein the processor is further configured to command: acquiring a position signal using the electrodes; and performing one or both of an adjustment of the placement of the catheter and a verification of the stability of the placement of the catheter based on the position signal.

8. The system of claim 1 , wherein the IC EP signal is an IC electrogram (EGM) signal.

9. 1. A method for atrial flutter discrimination, the method comprising: positioning a catheter comprising a plurality of electrodes within a coronary sinus (CS) of a patient's heart such that some of the electrodes overlie a left atrium (LA) of the heart and some of the electrodes overlie a right atrium (RA) of the heart; acquiring an intracardiac (IC) electrophysiological (EP) signal using said electrodes; estimating respective signal stability measures across the signals acquired by the electrodes overlapping the LA and across the signals acquired by the electrodes overlapping the RA; and indicating the atrium corresponding to the highest of the signal stability measures as a source of atrial flutter when one of the signal stability measures is above a first threshold while the other of the signal stability measures is below a second threshold.

10. The method of claim 9 , wherein the signal stability measures include correlation levels to respective reference IC signals.

11. The method of claim 10 , wherein the reference IC signal is obtained during a period of arrhythmia of the heart.

12. The method of claim 10 , wherein the reference IC signal is a template signal.

13. The method of claim 10 , wherein the reference IC signal was acquired during a previous cardiac cycle, and a correlation level below the second threshold indicates instability of the IC signal between cardiac cycles.

14. The method of claim 9 , wherein the electrodes are arranged in a linear array along the distal end of the catheter.

15. 10. The method of claim 9, comprising obtaining a position signal using the electrodes and performing one or both of adjusting placement of the catheter and verifying placement stability of the catheter based on the position signal.

16. The method of claim 9 , wherein the IC EP signal is an IC electrogram (EGM) signal.

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