EP-4740849-A2 - METHODS AND SYSTEMS FOR DETERMINING WHETHER R-WAVE DETECTIONS SHOULD BE CLASSIFIED AS FALSE DUE TO T-WAVE OVERSENSING (TWO) OR P-WAVE OVERSENSING (PWO)

EP4740849A2EP 4740849 A2EP4740849 A2EP 4740849A2EP-4740849-A2

Abstract

Described herein are methods and devices (801) for determining whether an R-wave detection should be classified as a false R-wave detection due to T-wave oversensing (TWO) or P-wave oversensing (PWO). One such method includes comparing a specific morphological characteristic (e.g., peak amplitude) associated with the R-wave detection to the specific morphological characteristic associated with each R-wave detection in a first set of earlier detected R-wave detections to thereby determine whether first TWO or PWO morphological criteria are met, and in a second set of earlier detected R-wave detections to thereby determine whether second TWO or PWO morphological criteria are met, wherein the second set differs from the first set but may have some overlap with the first set. The method also includes determining whether to classify the R-wave detection as a false R-wave detection, based on whether one of the first or second TWO or PWO morphological criteria are met.

Inventors

BADIE, NIMA
LI, WENWEN
QU, FUJIAN
GILL, JONG

Assignees

Pacesetter, Inc.

Dates

Publication Date: 20260513
Application Date: 20220421

Claims (15)

A device (801) comprising: two or more electrodes (800, 802, 804, 806, 808, 810); a sensing circuit (844) coupled to the two or more electrodes (800, 802, 804, 806, 808, 810) and configured to obtain a signal indicative of electrical activity of a patient's heart, wherein R-wave detections are made based on comparisons of the signal indicative of electrical activity of the patient's heart, or samples thereof, to an R-wave detection threshold; and a processor or controller (820) configured to: classify an R-wave detection as a false R-wave detection due to T-wave oversensing (TWO) or P-wave oversensing (PWO) when an R-R interval duration D(n) associated with the R-wave detection is: dissimilar to an R-R interval duration associated with an R-wave detection D(n-1) that was one R-wave detection earlier, and similar an R-R interval duration associated with an R-wave detection D(n-2) that was two R-wave detections earlier, or dissimilar to an R-R interval duration associated with the R-wave detection D(n-2) that was two R-wave detections earlier, and similar an R-R interval duration associated with an R-wave detection D(n-3) that was three R-wave detections earlier.
The device (801) of claim 1, wherein the processor is configured to determine that two R-R interval durations are similar to one another when a difference between the two R-R interval durations are within a specified threshold, and determine that two R-R interval durations are dissimilar to one another when a difference between the two R-R interval durations are beyond the specified threshold.
The device of any one of claims 1 or 2, wherein the processor is configured to determine that: the R-R interval duration D(n) is dissimilar to the R-R interval duration D(n-1) when a difference between the R-R interval duration D(n) and the R-R interval duration D(n-1) is beyond a specified threshold; the R-R interval duration D(n) is similar to the R-R interval duration D(n-2) when a difference between the R-R interval duration D(n) and the R-R interval duration D(n-2) is within the specified threshold; the R-R interval duration D(n) is dissimilar to the R-wave detection D(n-2) when a difference between the R-R interval duration D(n) and the R-R interval duration D(n-2) is beyond the specified threshold; and the R-R interval duration D(n) is similar to the R-R interval duration D(n-3) when a difference between the R-R interval duration D(n) and the R-R interval duration D(n-3) is within the specified threshold.
The device (801) of claim 1, wherein the processor is configured to determine that two R-R interval durations are similar to one another when a ratio of the two R-R interval durations is within a specified threshold, and determine that two R-R interval durations are dissimilar to one another when a ratio of the two R-R interval durations is outside the specified threshold.
The device (801) of any one of claims 1 or 4, wherein the processor is configured to determine that: the R-R interval duration D(n) is dissimilar to the R-R interval duration D(n-1) when a ratio of the R-R interval duration D(n) / R-R interval duration D(n-1) is beyond a specified threshold; the R-R interval duration D(n) is similar to the R-R interval duration D(n-2) when a ratio of the R-R interval duration D(n) / the R-R interval duration D(n-2) is within the specified threshold; the R-R interval duration D(n) is dissimilar to the R-wave detection D(n-2) when a ratio of the R-R interval duration D(n) / the R-R interval duration D(n-2) is beyond the specified threshold; and the R-R interval duration D(n) is similar to the R-R interval duration D(n-3) when a ratio of the R-R interval duration D(n) / the R-R interval duration D(n-3) is within the specified threshold.
The device (801) of any one of claims 4 or 5, wherein: the specified threshold comprises a range; a ratio is within the specified threshold when the ratio is within the range; and a ratio is beyond the specified threshold when the ratio is beyond the specified range.
The device of any one of claims 1 through 6, wherein the processor or controller is configured to classify an arrhythmia detection as a false arrhythmia detection when at least a threshold number of the R-wave detections within a window leading up to the arrhythmia detection are classified as being false R-wave detections due to TWO or PWO.
The device of any one of claims 1 through 7, wherein the processor or controller (820) is configured to adjust at least one parameter of the R-wave detection threshold based on results of determinations of whether R-wave detections should be classified as false R-wave detections due to TWO or PWO.
A device implemented method for determining whether an R-wave detection should be classified as a false R-wave detection due to T-wave oversensing (TWO) or P-wave oversensing (PWO), the method comprising: classifying an R-wave detection as a false R-wave detection due to T-wave oversensing (TWO) or P-wave oversensing (PWO) when an R-R interval duration D(n) associated with the R-wave detection is: dissimilar to an R-R interval duration associated with an R-wave detection D(n-1) that was one R-wave detection earlier, and similar an R-R interval duration associated with an R-wave detection D(n-2) that was two R-wave detections earlier, or dissimilar to an R-R interval duration associated with the R-wave detection that was two R-wave detections earlier D(n-2), and similar an R-R interval duration associated with an R-wave detection that was three R-wave detections earlier D(n-3).
The method of claim 9, further comprising determining that two R-R interval durations are similar to one another when a difference between the two R-R interval durations are within a specified threshold, and determining that two R-R interval durations are dissimilar to one another when a difference between the two R-R interval durations are beyond the specified threshold.
The method of any one of claims 9 or 10, further comprising: determining that the R-R interval duration D(n) is dissimilar to the R-R interval duration D(n-1) when a difference between the R-R interval duration D(n) and the R-R interval duration D(n-1) is beyond a specified threshold; determining that the R-R interval duration D(n) is similar to the R-R interval duration D(n-2) when a difference between the R-R interval duration D(n) and the R-R interval duration D(n-2) is within the specified threshold; determining that the R-R interval duration D(n) is dissimilar to the R-wave detection D(n-2) when a difference between the R-R interval duration D(n) and the R-R interval duration D(n-2) is beyond the specified threshold; and determining that the R-R interval duration D(n) is similar to the R-R interval duration D(n-3) when a difference between the R-R interval duration D(n) and the R-R interval duration D(n-3) is within the specified threshold.
The method of claim 9, further comprising determining that two R-R interval durations are similar to one another when a ratio of the two R-R interval durations is within a specified threshold, and determining that two R-R interval durations are dissimilar to one another when a ratio of the two R-R interval durations is outside the specified threshold; wherein optionally the specified threshold comprises a range, a ratio is within the specified threshold when the ratio is within the range, and a ratio is beyond the specified threshold when the ratio is beyond the specified range.
The method of any one of claims 9 or 12, further comprising: determining that the R-R interval duration D(n) is dissimilar to the R-R interval duration D(n-1) when a ratio of the R-R interval duration D(n) / R-R interval duration D(n-1) is beyond a specified threshold; determining that the R-R interval duration D(n) is similar to the R-R interval duration D(n-2) when a ratio of the R-R interval duration D(n) / the R-R interval duration D(n-2) is within the specified threshold; determining that the R-R interval duration D(n) is dissimilar to the R-wave detection D(n-2) when a ratio of the R-R interval duration D(n) / the R-R interval duration D(n-2) is beyond the specified threshold; and determining that the R-R interval duration D(n) is similar to the R-R interval duration D(n-3) when a ratio of the R-R interval duration D(n) / the R-R interval duration D(n-3) is within the specified threshold; wherein optionally the specified threshold comprises a range, a ratio is within the specified threshold when the ratio is within the range, and a ratio is beyond the specified threshold when the ratio is beyond the specified range.
The method of any one of claims 9 through 13, further comprising classifying an arrhythmia detection as a false arrhythmia detection when at least a threshold number of the R-wave detections within a window leading up to the arrhythmia detection are classified as being false R-wave detections due to TWO or PWO.
The method of any one of claims 9 through 14, further comprising: comparing a sensed signal indicative of electrical activity of a patient's heart, or samples thereof, to an R-wave detection threshold to thereby detect R-waves; and adjusting at least one parameter of the R-wave detection threshold based on results of determinations of whether R-wave detections should be classified as false R-wave detections due to TWO or PWO.

Description

FIELD OF TECHNOLOGY Embodiments described herein relate to analysis of an electrogram (EGM) or electrocardiogram (ECG) signal, and more specifically, to determining whether an R-wave detection should be classified as false due to T-wave oversensing (TWO) or P-wave oversensing (PWO). BACKGROUND Various types of implantable medical devices (IMDs) are used to monitor for cardiac arrythmias. Some types of IMDs, such as implantable cardiac pacemakers and implantable cardiac defibrillators (ICDs), are capable of providing appropriate therapy in response to detected cardiac arrythmias. The recent development of Non-vascular ICDs (NV-ICDs), otherwise known as Subcutaneous ICDs (S-ICDs), has streamlined the implantation process for ICD patients. While traditional ICDs can detect rhythms using bipolar intracardiac electrogram signals, S-ICDs rely on far-field subcutaneous EGMs. These far-field EGM, which resemble surface ECGs, often include significantly large P-waves and T-waves that can be erroneously over-sensed as an R-wave. Such oversensing can ultimately result in false detections of ventricular tachycardia (VT) or ventricular fibrillation (VF), and/or other types of arrhythmia, potentially leading to inappropriate therapy delivery (e.g., shocks). VT and VF can be detected by measuring and comparing R-R intervals, or running averages thereof, to VT and VF detection thresholds. False positive VT and VF detections are highly undesirable, because they can lead to delivery of inappropriate therapy, such as shocks, which can premature deplete the battery of an ICD, and may be painful to the patient. Other types of IMDs, such as insertable cardiac monitors (ICMs), are used for diagnostic purposes. ICMs have been increasingly used to diagnose cardiac arrhythmias including atrial fibrillation (AF). AF is a very common type of supraventricular tachycardia (SVT) which leads to approximately one fifth of all strokes, and is the leading risk factor for ischemic stroke. However, AF is often asymptomatic and intermittent, which typically results in appropriate diagnosis and/or treatment not occurring in a timely manner. To overcome this, many cardiac devices, such as ICMs, now monitor for AF by obtaining an electrogram (EGM) signal and measuring R-R interval variability based on the EGM signal. For example, an ICM or other IMD can compare measures of R-R interval variability to a variability threshold, to automatically detect AF when the variability threshold is exceeded. Indeed, ICMs predominantly identify AF by quantifying the variability in R-R intervals (i.e., by quantifying the variability in the timing of ventricular contractions). False positive AF detections are highly undesirable, as the burden of sorting through large numbers of clinically irrelevant episodes of AF can be time consuming and costly. Presently available P-wave and T-wave detection discriminator techniques are often unable or inadequate to correctly distinguish P-waves and T-waves from R-waves, often leading to over-sensed P-waves and over-sensed T-waves, both of which are types of false R-wave detections. Accordingly, there is a still a need for improved techniques for distinguishing P-waves and T-waves from R-waves, and for distinguishing over-sensed R-R intervals from true R-R intervals. That is, there is still a need for improved methods, devices and systems for distinguishing true R-wave detections from false R-wave detections, and more generally, for detecting T-wave oversensing (TWO) and/or P-wave oversensing (PWO). SUMMARY Certain embodiments of the present technology relate to methods and devices that can be used to determine whether an R-wave detection should be classified as a false R-wave detection due to TWO or PWO. In accordance with certain embodiments, a method includes comparing a specific morphological characteristic (e.g., a peak amplitude (A)) associated with an R-wave detection to the specific morphological characteristic associated with each R-wave detection in a first set of earlier detected R-wave detections to thereby determine whether first TWO or PWO morphological criteria are met, and in a second set of earlier detected R-wave detections to thereby determine whether second TWO or PWO morphological criteria are met, wherein the second set differs from the first set but may have some overlap with the first set. The method also includes determining whether to classify the R-wave detection as a false R-wave detection, based on whether one of the first or second TWO or PWO morphological criteria are met. In certain embodiments, the first set of earlier detected R-wave detections includes R-wave detections that were one, two, and three R-wave detections earlier; and the second set of earlier detected R-wave detections includes R-wave detections that were two, three, and four R-wave detections earlier. In certain such embodiments, determining whether to classify the R-wave detection as a false R-wave detection, comprises classifyi