Systems and methods for detecting atrial tachyarrhythmia using heart sounds

Patent metadata

Field	Value
Publication number	US-10182735-B2
Application number	US-201615335873-A
Country	US
Kind code	B2
Filing date	Oct 27, 2016
Priority date	Oct 29, 2015
Publication date	Jan 22, 2019
Grant date	Jan 22, 2019

Abstract

Systems and methods for detecting atrial tachyarrhythmias (AT) such as atrial fibrillation (AF) are disclosed. A medical system can include a cardiac signal sensor circuit to sense a cardiac electrical signal and a heart sound (HS) sensor to sense heart a HS signal. A cardiac electrical signal metric, including a cycle length variability or a detection of atrial electrical activity, can be generated from the cardiac electrical signal. A HS metric can be generated from the HS signal, including a status of detection of S4 heart sound or a S4 heart sound intensity indicator. The system can include an AT detector circuit that can detect an AT event, such as an AF event, using the cardiac electrical signal metric and the HS metric. The system can additionally classify the detected AT event as an AF or an atrial flutter event.

First claim

What is claimed is:

1. A system, comprising:
a first signal metric generator circuit configured to determine a cycle length variability (CLV) over measurements of multiple cardiac cycles from a patient;
a second signal metric generator circuit configured to generate an S4 heart sound metric indicative or correlative of atrial mechanical contraction using heart sound information of the patient; and
an atrial tachyarrhythmia (AT) detector circuit configured to detect an AT event of the patient using the determined CLV and the generated S4 heart sound metric.

2. The system of claim 1 , wherein the AT event includes an atrial fibrillation (AF), wherein the S4 heart sound metric includes an S4 detection status indicating whether an S4 heart sound is detected within a cardiac cycle, and wherein the AT detector circuit is configured to detect AF of the patient using the determined CLV and the S4 detection status indicating a non-detection of the S4 heart sound within the cardiac cycle.

3. The system of claim 1 , wherein the S4 heart sound metric includes an S4 detection status indicating whether an $4 heart sound is detected within a cardiac cycle or an S4 intensity indicator indicative of an intensity of a detected S4 heart sound, and wherein the AT detector circuit includes:
a first comparator circuit configured to compare the CLV value to a CLV threshold (CLV TH );
a second comparator circuit configured to compare the S4 intensity indicator of the detected S4 heart sound to an S4 intensity threshold (∥S4∥ TH ); and
a blending circuit configured to detect the AF event if (1) the CLV value exceeds the CLV TH , and (2) the S4 detection status indicates a non-detection of S4 heart sound, or the S4 intensity indicator falls below the ∥S4∥ TH .

4. The system of claim 1 , wherein the S4 heart sound metric includes an S4 intensity indicator indicative of an intensity of a detected S4 heart sound, and wherein the AT detector circuit includes:
a first counter circuit configured to determine a first relative number of a first subset of a plurality of CLV values computed over a plurality of cardiac cycles, each CLV within the first subset exceeding a CLV threshold;
a second counter circuit configured to determine a second relative number of a second subset of the plurality of cardiac cycles, each cardiac cycle within the second subset including a detected S4 heart sound with a corresponding S4 intensity indicator exceeding an S4 intensity threshold; and
a blending circuit configured to generate a composite score using the first and second relative numbers, and detect the AF event if the composite score meets a specified criterion.

5. The system of claim 1 , further comprising a beat selector circuit coupled to the second signal metric generator circuit, the beat selector circuit configured to select, from a plurality of cardiac cycles for detecting S4 heart sound, a subset of cardiac cycles each having an S4 heart sound metric including an S4 detection status indicating non-detection of the S4 heart sound within the corresponding cardiac cycle, or an S4 intensity indicator indicative of an intensity of a detected $4 heart sound falling below an S4 intensity threshold,
wherein the first signal metric generator circuit is configured to compute the CLV value using the selected subset of the cardiac cycles; and
wherein the AT detector circuit is configured to detect the AF event if the CLV value exceeds a CLV threshold.

6. The system of claim 1 , further comprising a beat selector circuit coupled to the first signal metric generator circuit, the beat selector circuit configured to select from a plurality of cardiac cycles a subset of cardiac cycles corresponding to the CLV exceeding a CLV threshold,
wherein the second signal metric generator circuit is configured to detect S4 heart sounds within the selected subset of the cardiac cycles and generate an S4 detection status indicating whether an S4 heart sound is detected within the selected subset of the cardiac cycles; and
wherein the AT detector circuit is configured to detect the AF event if the S4 detection status indicating non-detection of the S4 heart sound within the selected subset of the cardiac cycles, or the S4 intensity indicator falling below an S4 intensity threshold.

7. The system of claim 1 , wherein the S4 heart sound metric includes an S4 detection status indicating whether an S4 heart sound is detected within a cardiac cycle, the system further comprising:
an activity sensor circuit configured to detect a physical activity level of the patient, wherein the AT detector circuit is configured to:
detect the AF event using an atrial electrical activation if the detected physical activity level exceeds a specified activity threshold; or
detect the AF event using the detected S4 heart sound if the detected physical activity level falls below the specified activity threshold.

8. The system of claim 1 , wherein the S4 heart sound metric includes an S4 detection status indicating whether an S4 heart sound is detected within a cardiac cycle, the system further comprising:
a posture sensor circuit configured to detect a posture of the patient, wherein the AT detector circuit is configured to:
detect the AF event using an atrial electrical activation if the detected posture is a first posture; or
detect the AF event using the detected S4 heart sound if the detected posture is a different second posture.

9. The system of claim 1 , wherein
the AT detector circuit is configured to detect the AF event if the CLV value exceeds a CLV threshold (CLV TH ), wherein the CLV TH is determined using the determined S4 heart sound metric.

10. The system of claim 9 , wherein the S4 heart sound metric includes an S4 detection status indicating whether an S4 heart sound is detected within a cardiac cycle, and wherein the AT detector circuit is configured to:
determine a first CLV threshold (CLV TH1 ) in response to both of a detection of the S4 heart sound and a detection of an atrial electrical activation;
determine a second CLV threshold (CLV TH2 ) in response to one of a detection of the S4 heart sound or a detection of the atrial electrical activation; or
determine a third CLV threshold (CLV TH3 ) in response to neither a detection of the S4 heart sound nor a detection of the atrial electrical activation;
wherein the CLV TH1 is greater than the CLV TH2 , and the CLV TH2 is greater than the CLV TH3 .

11. The system of claim 1 , comprising an arrhythmia classifier circuit configured to
classify the detected AT event as an atrial fibrillation (AF) event or an atrial flutter (AFL) event using the determined CLV and the generated S4 heart sound metric.

12. The system of claim 11 , wherein the S4 heart sound metric includes an S4 detection status indicating whether an S4 heart sound is detected within a cardiac cycle, and wherein the determined CLV and the generated S4 heart sound metric includes a variability (AVR var ) of an atrio-ventricular conduction pattern including a ratio (AVR) of a number of detected S4 heart sounds to a number of ventricular activations during a specified number of cardiac cycles,
wherein the arrhythmia classifier circuit is configured to classify the detected AT event as an AF event if the AVR var exceeds a specified threshold, or classify the detected AT event as an AFL event if the AVR var falls below the specified threshold.

13. The system of claim 11 , wherein the determined CLV and the generated S4 heart sound metric includes a variability (AVI var ) of atrio-ventricular conduction delay including a time interval between the detected S4 heart sound and the ventricular

Assignees

• Cardiac Pacemakers Inc

Inventors

• Thakur Pramodsingh Hirasingh
• Mi Bin
• Simms Jr Howard D
• An Qi
• Hatlestad John D
• Maile Keith R

Classifications

• A61B5/686

  Permanently implanted devices, e.g. pacemakers, other stimulators, biochips (A61B5/6861 takes precedence) · CPC title

• A61B5/1116

  Determining posture transitions · CPC title

• A61B7/04

  Electric stethoscopes · CPC title

• A61B5/0245

  by using sensing means generating electric signals, {i.e. ECG signals} · CPC title

• A61B5/7275

  Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor · CPC title