ECG activation pattern clustering template analysis

Abstract

A method includes receiving a set of electrocardiograms (ECGs) determined to belong to a given morphological template indicative of a given type of arrhythmia. Using a localization algorithm, a percentage of the ECG in the set directed to the same source location of the given type of arrhythmia is calculated. The calculated percentage is compared to a predefined threshold percentage. If the percentage of the ECG is found to exceed the threshold percentage, the source location is reported to the user.

Description

Technical Field

[0001] The present disclosure generally relates to the analysis of electrocardiograms (ECGs), and more particularly to determining the source location of arrhythmias by analyzing ECGs. Background Art

[0002] Some types of ventricular arrhythmias such as premature ventricular contractions (PVCs) can be diagnosed using an ECG. For example, a 12-lead ECG is useful in providing initial evidence of PVC frequency and is a good non-invasive tool for determining the PVC source location and preferred entry regions. When PVCs are suspected based on a patient's medical history or physical examination, it is useful to perform a longer ECG acquisition (e.g., up to one minute) to better understand the PVC frequency and capture the PVC while recording all twelve synchronous leads for the most accurate morphological assessment.

[0003] A method for identifying PVCs by classifying at least one ECG as belonging to a given morphological template is provided in U.S. Patent 11,730,414, which describes in one embodiment a medical system including corresponding electrodes for application to a subject's body and a processor. The electrodes are configured to output a corresponding set of activation signals in response to the electrical activity of the subject's heart captured within a series of heartbeat intervals. The processor is configured to: classify a first heartbeat interval of the set of activation signals as a first morphological template; calculate a similarity measure between a second heartbeat interval of the set of activation signals and the first morphological template; group the second heartbeat interval of the set of activation signals in a first morphological group having the first morphological template in response to the measure exceeding a predefined threshold; and classify the second heartbeat interval of the set of activation signals as a second morphological template in response to the measure not exceeding the predefined threshold, and repeat the above process with appropriate adjustments in subsequent heartbeat intervals.

[0004] Some academic publications provide localization algorithms for estimating the source location of arrhythmias based on non-invasive ECG data such as 12-lead ECG or Holter monitoring. For example, Muzakkir Amir et al. in a paper titled "Park algorithm as a tool for predicting the origin of premature ventricular contractions in three-dimensional mapping electrophysiological studies" described the accuracy validation of the Park algorithm in predicting the origin location of PVCs with and / or without structural heart disease using a 12-lead ECG, which was published in the International Journal of General Medicine, Volume 13, pages 1083 - 1092 (2020). The researchers found that the Park algorithm is suitable for determining the location of PVC origin in the right or left heart.

[0005] Park et al. described their localization algorithm in a paper titled "Using Body Surface Electrocardiogram to Locate the Origin of Idiopathic Ventricular Tachycardia", which was published in the Journal of Heart Rhythm Society, Volume 35, Issue 12, pages 1516 - 1527 (2012).

[0006] In conjunction with the accompanying drawings, a more complete understanding of the present disclosure will be obtained through the following detailed description of examples of the present disclosure, where: BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a schematic diagram of a cardiac system configured for cardiac electrophysiology (EP) sensing, EP signal analysis, and ablation according to an example of the present disclosure;

[0008] Figure 2 is a schematic diagram of a morphological template for analyzing a 12 - lead ECG acquisition indicative of a given type of arrhythmia according to an example of the present disclosure; and

[0009] Figure 3 is a flowchart of a method for statistically determining the cardiac location source of an arrhythmia using a morphological template according to an example of the present disclosure. DETAILED DESCRIPTION

[0010] Overview

[0011] Premature ventricular contractions (PVCs) are extra heartbeats that originate from one of the ventricles of the heart. These extra beats disrupt the normal heart rhythm and sometimes cause a feeling of fluttering or irregular pulsations in the chest.

[0012] PVCs that cause ectopic beats can occur singly or in a repetitive pattern. The occurrence of three or more consecutive PVCs is classified as ventricular tachycardia (VT). One cause of ectopic beats is a re - entry signal, i.e., the beat is initiated by Purkinje fibers rather than the SA. For example, if one pathway of the Purkinje fibers is blocked and the other path has a slower conduction velocity, this may trigger an ectopic beat on the blocked - posterior pathway. In some cases, PVCs are thus treated by ablating the location of the ventricular tissue that causes the ectopic beats (e.g., the associated papillary muscle location).

[0013] Correctly estimating the ventricular source location of an arrhythmia using non - invasive ECG can be used to select the optimal invasive treatment option, such as catheter ablation. To this end, various localization algorithms, such as those described in the background section, have been developed to predict the source location of arrhythmias through non - invasive ECG techniques (e.g., 12 - lead, Holter monitoring).

[0014] However, given the importance of the decisions required (e.g., which invasive procedure to perform based on the estimated location), there are significant advantages to maximizing the confidence level in determining the source location.

[0015] Examples of the present disclosure described below provide techniques for determining the source location of arrhythmias such as PVCs with high confidence by analyzing non-invasively acquired ECGs (e.g., 12-lead acquired ECGs, Holter acquired ECGs). In one example, the disclosed algorithm enables a processor to identify the most repetitive representative 12-lead ECG heartbeat template for a PVC. Using statistical analysis on one or more patterns (i.e., morphological templates) enables the processor to verify the correct tissue source location in the heart with a high confidence level.

[0016] In one example, a processor receives a set of electrocardiograms (ECGs) determined to belong to a given morphological template (“ECG cluster”) indicative of a given type of arrhythmia, such as a set of ECGs obtained using the method described in the aforementioned U.S. Patent 11,730,414. A user may determine a threshold (match percentage) for inclusion in such a clustering. Using a localization algorithm, such as the Perkins algorithm described above (for PVCs), the processor calculates the percentage of ECGs in the given set that point to the same source location for the given type of arrhythmia. The processor then compares the calculated percentage to a predefined threshold percentage. If the calculated ECG percentage is found to exceed the threshold percentage, the processor reports the source to the user.

[0017] Since the number of ECGs in the set may total over a hundred, with a sufficient number of ECGs pointing to the same source location, a high level of statistical certainty can be obtained by this method. For example, if a sufficient percentage (e.g., dozens of ECGs) of the sufficient number of ECGs point to the same location (source) for a PVC, this effectively validates the accurate PVC source.

[0018] System Description

[0019] Figure 1 is a schematic diagram of a system 20 configured for cardiac electrophysiology (EP) sensing, EP signal analysis, and ablation according to an example of the present disclosure. System 20 includes a standalone ECG recorder 35. Recorder 35 is typically used by a physician to observe analog ECG signals, such as 12-lead ECG traces (also shown as traces 44 on display device 27).

[0020] System 20 includes a processing interface unit (PIU) 24, such as CARTO produced by Biosense-Webster TMThe processing interface unit used by the system. The ECG leads connected to the PIU 24 are sampled for further processing and are also directed to the recorder 35 for real-time display of the raw ECG signals. For clarity, components such as power cables, sockets, and inlets are omitted in Figure 1 For example.

[0021] As shown, the system 20 includes a catheter 21 having a shaft 22 that is navigated by a physician 30 into the heart 26 of a patient 28. In the illustrated example, the physician 30 inserts the shaft 22 through a sheath 23 while manipulating the shaft 22 using a manipulator 32 near the proximal end of the catheter.

[0022] The distal end 40 of the catheter 21 (shown in the inset 25) is equipped with electrodes that can be used for pacing, EP mapping, or ablation. The proximal end of the catheter 21 is connected to the PIU 24 and the recorder 35, for example, via the PIU 24 (e.g., connected via the output 55 of the PIU 24).

[0023] The PIU 24 receives an ECG waveform (e.g., trace) 44 from a body surface ECG patch 49. Typically, the patch 49 is attached to the skin around the chest and legs of the patient 28. The PIU 24 is connected to the patch 49 via wires through a cable 39 to receive signals from the ECG patch 49. The ECG trace 44 is displayed on a display device 27 (usually with a delay for the same ECG trace displayed on the recorder 35). Additionally, the recorder 35 can receive intracardiac signals acquired by the electrodes of the catheter 21.

[0024] The PIU 24 includes a processor 41, for example, which can be a general-purpose computer having a suitable front end and interface circuitry 38 for receiving various signals. In one example of the disclosed technology, the processor 41 applies algorithms to (a) cluster the ECG trace 44 and (b) analyze the clustered ECG acquired over a given number of heartbeats to point to the location (source) of ventricular arrhythmias such as PVCs.

[0025] In another example, the processor 41 uses the information contained in the intracardiac ECG signals obtained using the catheter 21 to construct an electrophysiological map 31 and present it on the display device 27.

[0026] During an EP mapping procedure, the position of the catheter can be tracked while the catheter is within the patient's heart 26. Such tracking can be performed using an Active Current Location (ACL) system manufactured by Biosense-Webster, Inc., which is described in U.S. Patent 8,456,182, the disclosure of which is incorporated herein by reference.

[0027] Processor 41 can thus associate any given signal received from the catheter, such as an intracardiac ECG, with the location where the signal was acquired. Processor 41 uses the information contained in these signals to construct an EP mapping, such as a local activation time (LAT) mapping, for presentation on a display. To perform ablation, the electrodes of the catheter can be connected (e.g., switched) to generator 47.

[0028] Processor 41 is typically programmed with software to perform the functions described herein. For example, the software can be downloaded electronically to the processor via a network, or alternatively or in addition, the software can be provided and / or stored on a non-transitory tangible medium such as magnetic, optical, or electronic memory.

[0029] ECG activation patterns aggregated into morphological templates

[0030] Figure 2 is a schematic diagram of a morphological template 202 for analyzing the morphology of a 12-lead ECG acquisition indicative of a given type of arrhythmia according to an example of the present disclosure. Figure 2 An ECG 204 acquired using a 12-lead ECG recorder is shown. The morphological template 202 can be used in conjunction with the method of the above-mentioned U.S. Patent 11,730,414 to acquire a set of ECGs suitable for the statistical analysis method disclosed in this application. For example, assuming a heart rate of 60 BPM, 60 ECG patterns are acquired, a portion of which may represent normal sinus rhythm and are clustered using a normal sinus rhythm template (not shown), while another portion will belong to the categories defined by the morphological template 202.

[0031] Using the disclosed technique, which applies a localization algorithm to the ECGs belonging to the morphological template 202 in a first step, a clinician can statistically evaluate the confidence level of a given source location's involvement in generating an abnormal ECG. Based on this confidence level, the type of invasive clinical method can be decided according to the clinician's judgment.

[0032] Statistically determining the cardiac location source of arrhythmias using morphological templates

[0033] Figure 3 is a flowchart of a method for statistically determining the cardiac location source of an arrhythmia using a morphological template according to an example of the present disclosure. The process executes an algorithm that begins with processor 41 receiving, at a data reception step 302, a set of ECGs determined to belong to a given morphological template 202 indicative of a given type of arrhythmia.

[0034] Next, at a calculation step 304, using the localization algorithm, processor 41 calculates the percentage of ECGs in the given set that point to the same source location of a given type of arrhythmia. For example, the processor calculates the fraction of ECGs that point to the ventricular tissue source location of PVCs.

[0035] At the percentage comparison step 306, the processor compares the calculated percentage with a predefined threshold percentage.

[0036] At the checking step 308, the processor checks the result of the comparison. If it is found that the percentage of the ECG exceeds the threshold percentage, then at the reporting step 310, the processor reports the source location to the user. This report can be a note on the display device 27 and / or a highlighted area in the 3D anatomical model shown on the display device.

[0037] Figure 3 The flowchart of is given by way of example and is simplified for clarity of presentation. In another example, the disclosed method is applied once to a set of ECGs collected under different morphological templates.

[0038] Examples

[0039] Example 1

[0040] A method includes: receiving a set of electrocardiograms (ECGs) determined to belong to a given morphological template (202) indicating a given type of arrhythmia. Using a localization algorithm, calculating the percentage of the ECGs in the set that point to the same source location of the given type of arrhythmia. Comparing the calculated percentage with a predefined threshold percentage. If it is found that the percentage of the ECGs exceeds the threshold percentage, then reporting the source location to the user (30).

[0041] Example 2

[0042] The method according to embodiment 1, wherein the morphological template (202) indicates an arrhythmia of the premature ventricular contraction (PVC) type.

[0043] Example 3

[0044] The method according to any one of examples 1 and 2, wherein reporting the source location includes reporting an anatomical region within the heart (26).

[0045] Example 4

[0046] The method according to any one of embodiments 1 to 3, wherein the set of ECGs is acquired using a 12-lead ECG recorder (35).

[0047] Example 5

[0048] A system (20) includes an interface (24) and a processor (41). The interface (24) is configured to receive a set of electrocardiograms (ECGs) determined to belong to a given morphology template (202) indicative of a given type of arrhythmia. The processor (41) is configured to: (i) use a localization algorithm to calculate a percentage of the ECGs in the set that point to the same source location of the given type of arrhythmia, (ii) compare the calculated percentage with a predefined threshold percentage, and (iii) if the percentage of the ECGs is found to exceed the threshold percentage, report the source location to a user (30).

[0049] Although the examples described herein are mainly directed to cardiac diagnostic applications, the methods and systems described herein can also be used in other medical applications.

[0050] It should be understood that the above examples are cited by way of illustration, 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 their variations and modifications, which would 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 a set of electrocardiograms (ECGs) determined to belong to a given morphology template indicative of a given type of arrhythmia; using a localization algorithm, calculating the percentage of the ECGs in the group that point to the same source location for the given type of arrhythmia; comparing the calculated percentage to a predefined threshold percentage; as well as If the percentage of the ECG is found to exceed the threshold percentage, the source location is reported to the user.

2. The method according to claim 1, wherein The morphology template is indicative of premature ventricular contraction (PVC) type arrhythmia.

3. The method according to claim 1, wherein Reporting the source location includes reporting an anatomical region within the heart.

4. The method according to claim 1, wherein The set of ECGs was acquired using a 12-lead ECG recorder.

5. A system comprising: an interface configured to receive a set of electrocardiograms (ECGs) determined to belong to a given morphology template indicative of a given type of arrhythmia; and A processor configured to: using a localization algorithm, calculating the percentage of the ECGs in the group that point to the same source location for the given type of arrhythmia; comparing the calculated percentage to a predefined threshold percentage; as well as If the percentage of the ECG is found to exceed the threshold percentage, the source location is reported to the user.

6. The system according to claim 5, wherein, The morphology template is indicative of premature ventricular contraction (PVC) type arrhythmia.

7. The system according to claim 5, wherein The processor is configured to report the source location by reporting an anatomical region within the heart.

8. The system according to claim 5, wherein The set of ECGs was acquired using a 12-lead ECG recorder.

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