CN-122028848-A - Selectable heart sound tracking in heart failure

CN122028848ACN 122028848 ACN122028848 ACN 122028848ACN-122028848-A

Abstract

Systems and methods for identifying and tracking heart sound components are disclosed. An exemplary medical device system includes a data receiver that receives heart sound information and a heart sound identification circuit that generates a representative heart sound segment (such as a ensemble average of selected portions of the heart sound segment). The heart sound identification circuit identifies heart sound components from the representative heart sound segments using a time-based tracking algorithm and evaluates a performance index of the time-based heart sound tracking algorithm. Based on the performance index, a decision may be made whether to switch to a spectrum-based tracking algorithm to identify the heart sound component from the representative heart sound segment. The physiological event detector may detect cardiac events using the identified heart sound component.

Inventors

Mojigan Gofertari
Victoria A. Averina
Jonathan Bennett Schutter

Assignees

心脏起搏器股份公司

Dates

Publication Date: 20260512
Application Date: 20241106
Priority Date: 20231116

Claims (15)

1. A medical device system, comprising: A data receiver circuit configured to receive heart sound information over a plurality of cardiac cycles, and A heart sound identification circuit configured to: generating a representative heart sound segment within the cardiac cycle using at least a portion of the received heart sound information; identifying a heart sound component from the representative heart sound segment using a time-based heart sound tracking algorithm; Evaluating a performance index of the time-based heart sound tracking algorithm using morphology or timing information of the identified heart sound component, and Based on the assessed performance index, it is determined whether to switch to a spectrum-based heart sound tracking algorithm to identify the heart sound component from the representative heart sound segment.
2. The medical device system of claim 1, wherein the time-based heart sound tracking algorithm uses amplitude and timing information of the representative heart sound segment to identify the heart sound component.
3. The medical device system of any one of claims 1-2, wherein the spectrum-based heart sound tracking algorithm identifies the heart sound component using one or more spectral entropy values calculated from the representative heart sound segment.
4. The medical device system of any one of claims 1-3, wherein the portion of the received heart sound information includes a plurality of heart sound segments corresponding to respective heart beats, Wherein the heart sound identification circuit is configured to generate the representative heart sound segment using ensemble averaging of at least a subset of the plurality of heart sound segments.
5. The medical device system of claim 4, wherein the data receiver circuit is configured to receive information regarding an instantaneous heart rate of heart beats corresponding to the plurality of heart sound segments, Wherein at least a subset of the plurality of heart sound segments used to generate the representative heart sound segment corresponds to heart beats falling within a predetermined heart rate range.
6. The medical device system of claim 5, wherein to generate the representative heart sound segment, the heart sound identification circuit is configured to: sorting the plurality of heart sound segments according to a particular order of instantaneous heart rates of heart beats corresponding to the plurality of heart sound segments; Identifying from the ordered plurality of heart sound segments at least a first set of heart sound segments corresponding to a first heart beat and a second set of heart sound segments corresponding to a second heart beat, the second heart beat having a different heart rate than the first heart beat; determining a first morphological similarity measure of the first set of heart sound segments and a second morphological similarity measure of the second set of heart sound segments; Selecting a group between the first group and the second group based on one or more of the first morphological similarity measure or the second morphological similarity measure, and The representative heart sound segment is generated using ensemble averaging of the heart sound segments of the selected group.
7. The medical device system of claim 6, wherein the first and second groups each have at least a certain minimum number of heart sound segments.
8. The medical device system of any of claims 6-7, wherein a first heart beat corresponding to the first set of heart sound segments and a second heart beat corresponding to the second set of heart sound segments each have a respective instantaneous heart rate that falls below a heart rate threshold.
9. The medical device system of any one of claims 6-8, wherein a first heart beat corresponding to the first set of heart sound segments and a second heart beat corresponding to the second set of heart sound segments each have a respective instantaneous heart rate that meets a heart rate variability or range requirement.
10. The medical device system of any one of claims 6-9, wherein the plurality of heart sound segments are ordered according to an ascending order of the instantaneous heart rate of the heart beat, Wherein the second heart beat corresponding to the second set of heart sound segments has a higher heart rate than the first heart beat corresponding to the first set of heart sound segments, Wherein selecting between the first set and the second set comprises: selecting the first set if (i) the first morphological similarity measure is above a first threshold, or (ii) both the first and second morphological similarity measures are below respective thresholds, and the first morphological similarity measure is greater than the second morphological similarity measure, and The second set is selected if (i) the first morphological similarity measure is below the first threshold and the second morphological similarity measure is above a second threshold, or (ii) both the first and second morphological similarity measures are below respective thresholds and the second morphological similarity measure is greater than the first morphological similarity measure.
11. The medical device system of any one of claims 4-10, wherein the heart sound identification circuit is configured to assess a performance index of the time-based heart sound tracking algorithm using a morphological similarity measure between at least a subset of the plurality of heart sound segments used to generate the representative heart sound segment.
12. The medical device system of claim 11, Wherein assessing the performance index of the time-based heart sound tracking algorithm comprises further using heart sound tracking stability indicative of a variability in timing of heart sound components respectively determined from at least a subset of the plurality of heart sound segments used to generate the representative heart sound segment, Wherein, to determine whether to switch to the spectrum-based heart sound tracking algorithm, the heart sound identification circuit is configured to: if (i) the morphological similarity measure exceeds a similarity threshold and (ii) the heart sound tracking stability is below a variability threshold, determining not to switch to the spectrum-based heart sound tracking algorithm to identify the heart sound component from the representative heart sound segment, and If (i) the morphological similarity measure is not greater than the similarity threshold, or (ii) the heart sound tracking stability exceeds the variability threshold, determining to switch to the spectrum-based heart sound tracking algorithm to identify the heart sound component from the representative heart sound segment.
13. The medical device system of claim 12, wherein the heart sound tracking stability indicates variability in timing of the S2 component, Wherein the heart sound identification circuit is configured to determine, for each of at least a subset of the plurality of heart sound segments used to generate the representative heart sound segment, an aortic valve stenosis (AS) index indicating a presence or severity of an AS, and to determine the heart sound tracking stability using a variability of the determined AS index.
14. The medical device system according to any one of claim 4 to 13, Wherein, to assess the performance index of the time-based heart sound tracking algorithm, the heart sound identification circuit is configured to: Generating a heart sound timing trend comprising a time series of timings of heart sound components identified from at least a subset of the plurality of heart sound segments using the time-based heart sound tracking algorithm; Generating a heart rate trend comprising a time series of instantaneous heart rates of heart beats corresponding to at least a subset of the plurality of heart sound segments, and A performance index of the time-based heart sound tracking algorithm is assessed using a measure of correspondence between the heart sound timing trend and the heart rate trend, Wherein, to determine whether to switch to the spectrum-based heart sound tracking algorithm, the heart sound identification circuit is configured to: Determining not to switch to the spectrum-based heart sound tracking algorithm to identify the heart sound component from the representative heart sound segment if the consistency metric falls below a threshold value, and If the consistency metric exceeds the threshold, a switch to the spectrum-based heart sound tracking algorithm is determined to identify the heart sound component from the representative heart sound segment.
15. The medical device system of any one of claims 1 to 14, further comprising a physiological event detector configured to detect cardiac events using the identified heart sound component.

Description

Selectable heart sound tracking in heart failure Priority claim The application claims the benefit of U.S. provisional application No. 63/599,867, filed on 11/16 of 2023, which is incorporated herein by reference in its entirety. Technical Field This document relates generally to medical systems, and more particularly, to systems, devices, and methods for identifying and tracking heart sounds of a subject. Background Heart sounds are often associated with mechanical vibrations of the heart and blood flow through the heart. Heart sounds repeatedly occur with each cardiac cycle and are separated and classified according to the activity associated with the vibrations. Historically, heart sounds were assessed by humans and therefore only the audible part of the vibration was used. The device can now evaluate the full spectrum of heart vibrations, which includes both audible and sub-audible components, so the term "sound" in this document refers to the full spectrum of vibrations. Typically, heart sounds sensed from a subject may include several components within the cardiac cycle, including a first heart sound (S1), a second heart sound (S2), a third heart sound (S3), or a fourth heart sound (S4). S1 is associated with vibrations generated by the heart during mitral valve tensioning. S2 results from the closure of the aortic and pulmonary valves and marks the onset of diastole. S3 results from early diastolic vibration corresponding to passive ventricular filling during diastole (when blood rushes into the ventricle). S4 results from late diastolic vibration corresponding to active ventricular filling where the atrium contracts and pushes blood into the ventricle. In healthy subjects, S3 is usually weak and S4 is rarely heard. However, pathological S3 or S4 may be louder and louder. Heart sounds have been used to assess heart contractile and diastolic function. Systole is the contraction of the heart or a period of time that results in blood being forced out of the heart, such as the heart chamber, and into the aorta and pulmonary arteries. Relaxation is relaxation of the heart or a period of relaxation during which blood flows back to the heart, such as the heart chamber. Patients with heart disease may have deteriorated systole or diastole function. For example, congestive heart failure (congestive heart failure, CHF) occurs when the heart is unable to supply enough blood to maintain a healthy physiological state. Implantable medical devices (Implantable MEDICAL DEVICE, IMD) have been used to monitor heart disease patients, such as to detect cardiac events that lead to worsening heart failure (worsening heart failure, WHF). The IMD may sense physiological signals from the patient and deliver electrical stimulation therapy to improve cardiac performance in CHF patients. Frequent patient monitoring via an IMD may help identify patients at elevated risk of developing future heart failure events, ensure timely treatment, reduce heart failure hospitalization, improve patient outcome, and reduce medical care costs. Disclosure of Invention An Ambulatory Medical Device (AMD), such as an Implantable Medical Device (IMD), a subcutaneous medical device, a wearable medical device, or other external medical device, may be used to monitor cardiac patients. AMD can sense electrical or mechanical activity of the heart via sensing electrodes and/or physiological sensors, and detect cardiac events, such as cardiac arrhythmias or WHF. The IMD may include a pulser that is capable of generating and delivering electrical stimulation therapy to the heart or other excitable tissue (e.g., a neural target site) to restore or improve cardiac performance in CHF patients, or to correct cardiac arrhythmias. For example, detection of a cardiac arrhythmia may trigger cardiac pacing or shock, or detection of a WHF event may trigger electrical stimulation therapy, such as resynchronization therapy (resynchronization therapy, CRT), to correct cardiac dyssynchrony in heart failure patients. AMD can use heart sounds detected from a patient to detect cardiac events. For example, S1 and/or S2 may be used to detect cardiac arrhythmias, such as supraventricular tachycardia or ventricular tachycardia. Pulmonary fluid accumulation in CHF patients may lead to elevated ventricular filling pressures and diastolic dysfunction, resulting in pathologically louder S3.CHF patients may develop intense S4 against the intense atrial contraction of the abnormally stiff ventricles. Thus, monitoring S3 or S4 may be helpful in determining diastolic dysfunction in a patient, detecting a WHF event, or assessing the risk of a patient developing future WHF. Mobile heart sound detection involves placing a heart sound sensor at an epidermal, subcutaneous, sub-muscular, intramuscular, or sub-sternal location at or near the heart. A heart sound sensor, such as an accelerometer, may be included within the IMD for implantation, or associated with an implantable lead for epica