HARNESSING S1 VARIABILITY FOR AF DETECTION

• US 20170209061A1
• Filed: 01/17/2017
• Published: 07/27/2017
• Est. Priority Date: 01/22/2016
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Mi, Bin, Simms, JR., Howard D., Maile, Keith R., Hatlestad, John D., Thakur, Pramodsingh Hirasingh, An, Qi
• Granted Patent: US 10,194,819 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 2562/0204 Acoustic sensors
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/35 by template matching
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/361 Detecting fibrillation
• CPC Class Codes: A61B 7/00 Instruments for auscultation
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R

Abstract

This document discusses, among other things, systems and methods to determine amplitude and morphology variations of a first heart sound over a first number of cardiac cycles, and to calculate an atrial fibrillation metric indicative of an atrial fibrillation episode of the heart using the determined amplitude and morphology variations. The systems and methods can determine a variability score using the determined amplitude and morphology variations, and can calculate the atrial fibrillation metric using the variability score.

Claims

1. A system, comprising:

a heart sound signal input circuit configured to receive heart sound information of a heart over a first interval, the first interval including at least a portion of each of a first number of cardiac cycles;

a heart sound variability circuit configured to determine an amplitude variation of a first heart sound of the heart sound information over the first interval, or to determine a morphology variation of the first heart sound over the first interval; and

an atrial fibrillation detection circuit configured to calculate an atrial fibrillation metric indicative of an atrial fibrillation episode of the heart for the first interval using the determined amplitude variation or morphology variation.

2. The system of claim 1, wherein the heart sound variability circuit is configured to determine a variability score of the first heart sound for the first interval using the determined amplitude and morphology variations.

3. The system of claim 2, wherein the atrial fibrillation detection circuit is configured to calculate the atrial fibrillation metric using the variability score.

4. The system of claim 1, including:

an electrical signal input circuit configured to receive an electrical signal of the heart over the first interval,

wherein the heart sound information includes a heart sound signal of the heart, and

wherein the heart sound signal input circuit is configured to detect the first heart sound of the heart sound signal using the electrical signal of the heart.

5. The system of claim 4, including an implantable medical device including the heart sound signal input circuit, the electrical signal input circuit, and the heart sound variability circuit,

wherein the heart sound variability circuit is coupled to the heart sound signal and electrical signal input circuits.

6. The system of claim 1, wherein the morphology variation of the first heart sound includes a variation in a shape of the first heart sound.

7. The system of claim 6, wherein the variation in the shape of the first heart sound includes a variation in an offset between first and second features of the first heart sound in a first cardiac cycle and an offset between the first and second features of the first heart sound in a second cardiac cycle.

8. The system of claim 6, wherein the variation in the shape of the first heart sound includes a variation in a function of a first- or higher-order derivative of a portion of the first heart sound in a first cardiac cycle and a function of a first- or higher-order derivative of the portion of the first heart sound in a second cardiac cycle.

9. The system of claim 1, wherein the morphology variation of the first heart sound includes a timing of the first heart sound.

10. The system of claim 1, wherein the atrial fibrillation detection circuit is configured to provide an alert using the atrial fibrillation metric.

11. A method, comprising:

receiving heart sound information of a heart over a first interval, the first interval including at least a portion of each of a first number of cardiac cycles;

determining an amplitude variation of a first heart sound of the heart sound information over the first interval using a heart sound variability circuit, or determining a morphology variation of the first heart sound over the first interval using a heart sound variability circuit; and

calculating, using an atrial fibrillation detection circuit, an atrial fibrillation metric indicative of an atrial fibrillation episode of the heart for the first interval using the determined amplitude variation or morphology variation.

12. The method of claim 11, including:

determining, using the heart sound variability circuit, a variability score of the first heart sound for the first interval using the determined amplitude and morphology variations,

wherein calculating the atrial fibrillation metric includes using the determined variability score.

13. The method of claim 12, including:

receiving an electrical signal of the heart over the first interval using an electrical signal input circuit;

receiving a heart sound signal of the heart using a heart sound signal input circuit; and

detecting, using the heart sound signal input circuit, the first heart sound of the heart sound signal using the electrical signal of the heart.

14. The method of claim 12, wherein determining the morphology variation of the first heart sound includes determining a variation in a shape of the first heart sound.

15. The method of claim 14, wherein determining the variation in the shape of the first heart sound includes determining a variation in an offset between first and second features of the first heart sound in a first cardiac cycle an offset between the first and second features of the first heart sound in a second cardiac cycle.

16. The method of claim 14, wherein determining the variation in the shape of the first heart sound includes determining a variation in a function of a first- or higher-order derivative of a portion of the first heart sound in a first cardiac cycle and a function of a first- or higher-order derivative of the portion of the first heart sound in a second cardiac cycle.

17. The method of claim 12, wherein determining the morphology variation of the first heart sound includes determining a timing of the first heart sound.

18. The method of claim 12, including providing an alert, using the atrial fibrillation detection circuit, based on the atrial fibrillation metric.

19. At least one machine readable medium including instructions that, when executed by at least one processor, configure the at least one processor to:

receive heart sound information of a heart over a first interval, the first interval including at least a portion of each of a first number of cardiac cycles;

determine an amplitude variation of a first heart sound of the heart sound information over the first interval using a heart sound variability circuit;

determine a morphology variation of the first heart sound over the first interval using a heart sound variability circuit; and

calculate, using an atrial fibrillation detection circuit, an atrial fibrillation metric indicative of an atrial fibrillation episode of the heart for the first interval using the determined amplitude and morphology variations.

20. The at least one machine readable medium of claim 19, wherein the morphology variation of the first heart sound includes at least one of a variation in a shape of the first heart sound, or a variation in a timing of the first heart sound,

wherein the variation in the shape of the first heart sound includes at least one of:

an offset between first and second features of the first heart sound in a first cardiac cycle an offset between the first and second features of the first heart sound in a second cardiac cycle;

or

a variation in a function of a first- or higher-order derivative of a portion of the first heart sound in a first cardiac cycle and a function of a first- or higher-order derivative of a portion of the first heart sound in a second cardiac cycle, and

wherein the at least one machine readable medium includes instructions that, when executed by the at least one processor, configure the at least one processor to provide an alert based on the atrial fibrillation metric.