# US 2018/0020987 A1 · Indication of risk for coronary artery disease

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- Number: US 2018/0020987 A1
- Document ID: US20180020987A1
- Status: Published application
- Kind: A1
- Application number: 15/551,356
- Filed: 2016-04-08
- Published: 2018-01-25
- Earliest claimed: 2015-04-09
- Assignees: Acarix AS
- Applicants: Acarix AS
- Inventors: Samuel Emil Schmidt; Johannes Jan Struijk
- Web page: https://patentgrep.com/patent/US20180020987A1

## CPC

- A61B 5/7275: {Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor}
- A61B 5/02444: {Details of sensor (A61B5/02427 takes precedence)}
- A61B 5/7203: {for noise prevention, reduction or removal}
- A61B 5/721: {using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured}
- A61B 5/7235: {Details of waveform analysis (detecting specific parameters of the electrocardiograph cycle A61B5/349)}
- A61B 5/7246: {using correlation, e.g. template matching or determination of similarity}
- A61B 5/7278: {Artificial waveform generation or derivation, e.g. synthesizing signals from measured signals}
- A61B 7/026: {comprising more than one sound collector}
- A61B 7/04: Electric stethoscopes
- G16H 40/63: for local operation
- G16H 50/30: for calculating health indices; for individual health risk assessment
- A61B 5/352: Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
- A61B 2562/0204: Acoustic sensors
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G16H: HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA

## Abstract

A way of indicating a risk for coronary artery disease is disclosed. A first plurality of first sound recordings of heartbeats and second plurality of second sound recording of the ambient background are obtained. A filtering of each first sound recording is performed by using a simultaneously recorded second sound recording. The filtering of each first sound recording involves determining a diastolic period of the heartbeat of the first sound recording, and performing an adaptive filtering of the first sound recording based in the diastolic period of the first sound recording and the simultaneously recorded second sound recording. This is followed by determination of an indication of the risk for coronary artery disease based on the filtered first sound recordings.

## Claims

### Claim 1

A method for indicating a risk for coronary artery disease for a person, the method comprising;
(a) obtaining a first plurality of first sound recordings, wherein each first recording is of a heartbeat of the person,
(b) obtaining a second plurality of second sound recording, wherein each second sound recording is of an ambient background surrounding the person and being recorded simultaneously to a first sound recording of the first plurality,
(c) performing a filtering of each first sound recording of the first plurality by using a simultaneously recorded second sound recording of the second plurality, the filtering of each first sound recording comprises:
(i) determining a diastolic period of the heartbeat of the first sound recording, and
(ii) determining a first portion of the first sound recording and a second portion of the simultaneously recorded second sound recording, wherein the first portion and the second portion are covered by the diastolic period,
(iii) determining an adaptive filter for the first sound recording, wherein the adaptive filter is based on the first portion and the second portion and configured for reducing noise originating from the ambient background that is present in both the first sound recording and in the simultaneously recorded second sound recording, and
(iv) employing the adaptive filter to the first sound recording, and
(d) determining an indication of the risk for coronary artery disease based on the filtered first sound recordings of the first plurality.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the step (d) of determining an indication comprises:
(d1) determining one or more first heart sound levels from the filtered first sound recordings, wherein each first heart sound level is determined from a first period within a filtered first sound recording, and
(d2) determining the risk for coronary artery disease based on the one or more first heart sound levels.

### Claim 3 (depends on 2)

The method according to claim 2, wherein the first period corresponds to a period within the diastolic period.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the first portion and the second portion are of equal length and the first portion and the second portion are concurrent.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the adaptive filter is based on a Wiener filter and the adaptive filtering may be applied to the first portion of the first sound recording.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the method further comprises prior to the step (c) of performing the filtering:
(e) determining a first noise level of each second sound recording of the second plurality, wherein the first noise level is based on a variance of a sound level of the complete second sound recording, and
(f) discarding the first sound recordings having a simultaneously recorded second recording with a first noise level above a first determined noise level, wherein the first determined noise level is approximately 65 dB.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the method further comprises prior to the step (c) of performing the filtering:
(g) determining a second heart sound level of each first sound recording of the first plurality, wherein the second heart sound level is based on a mean or variance of a sound level of the complete first sound recording, and
(h) discarding the first sound recordings having a second heart sound level that is below a first determined heart sound level, wherein the first determined heart sound level is approximately 60 dB.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the method further comprises subsequent to step (c) of performing the filtering and prior to the step (d) of determining an indication:
(i) determining a second noise level for a second period of each second sound recording of the second plurality, wherein the second period corresponds to the first period and the second noise level is based on a variance of the second period, and
(j) discarding each first sound recordings having a simultaneously recorded second recording with a second noise level in the second period above a second determined noise level, wherein the second determined noise level is approximately 60 dB.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the method further comprises subsequent to step (c) of performing the filtering and prior to the step (d) of determining an indication:
(k) determining a third heart sound level for a third period of each first sound recording of the first plurality, wherein the third period corresponds to the first period and the third heart sound level is based on a median of the variance of the sound levels of the third periods, and
(l) discarding the first sound recording if the third heart sound level exceeds a second determined heart sound level, wherein the determined third heart sound level is approximately 3 dB greater than the median of the mean or variance of the sound levels of the third periods.

### Claim 10

A system for indicating a risk for coronary artery disease for a person, wherein the system comprises;
(A) a first acoustic sensor configured to be placed on the chest of the person and for recording heartbeats,
(B) a second acoustic sensor configured to be placed at the person and for recording ambient background sounds,
(C) a processor operatively connected with the first acoustic sensor and the second acoustic sensor and configured to:
(a) obtain a first plurality of first sound recordings with the first acoustic sensor, wherein each first recording is of a heartbeat of the person,
(b) obtain a second plurality of second sound recording with the second acoustic sensor, wherein each second sound recording is of the ambient background surrounding the person and being recorded simultaneously to a first sound recording of the first plurality,
(c) perform a filtering of each first sound recording of the first plurality by using a simultaneously recorded second sound recording of the second plurality, the filtering of each first sound recording comprises:
(i) determining a diastolic period of the heartbeat of the first sound recording, and
(ii) determining a first portion of the first sound recording and a second portion of the simultaneously recorded second sound recording, wherein the first portion and the second portion are covered by the diastolic period,
(iii) determining an adaptive filter for the first sound recording, wherein the adaptive filter is based on the first portion and the second portion and configured for reducing noise originating from the ambient background that is present in both the first sound recording and in the simultaneously recorded second sound recording, and
(ivi) employing the adaptive filter to the first sound recording, and
(d) determining an indication of the risk for coronary artery disease based on the filtered first sound recordings of the first plurality.

### Claim 11 (depends on 10)

The system according to claim 10, wherein the system further comprises a support for supporting the first acoustic sensor and the second acoustic sensor and for positioning the second acoustic sensor at the first acoustic sensor.

### Claim 12

A computer program product for being used in a system comprising: (A) a first acoustic sensor configured to be placed on the chest of a person and for recording heartbeats, (B) a second acoustic sensor configured to be placed at the person and for recording ambient background sounds, and (C) a processor operatively connected with the first acoustic sensor and the second acoustic sensor, the computer program product comprising program code instructions configured to, when executed by the processor of the system, cause the processor to:
(a) obtain a first plurality of first sound recordings with the first acoustic sensor, wherein each first recording is of a heartbeat of the person,
(b) obtain a second plurality of second sound recording with the second acoustic sensor, wherein each second sound recording is of the ambient background surrounding the person and being recorded simultaneously to a first sound recording of the first plurality,
(c) perform a filtering of each first sound recording of the first plurality by using a simultaneously recorded second sound recording of the second plurality, the filtering of each first sound recording comprises:
(i) determining a diastolic period of the heartbeat of the first sound recording, and
(ii) determining a first portion of the first sound recording and a second portion of the simultaneously recorded second sound recording, wherein the first portion and the second portion are covered by the diastolic period,
(iii) determining an adaptive filter for the first sound recording, wherein the adaptive filter is based on the first portion and the second portion and configured for reducing noise originating from the ambient background that is present in both the first sound recording and in the simultaneously recorded second sound recording, and
(iv) employing the adaptive filter to the first sound recording, and
(d) determining an indication of the risk for coronary artery disease based on the filtered first sound recordings of the first plurality.

### Claim 13

A method for filtering a first sound recording of a heartbeat of a person by using a second sound recording of the ambient background surrounding the person, wherein the second sound recording is recorded simultaneously to the first sound recording, the method comprises:
(i) determining a diastolic period of the heartbeat of the first sound recording, and
(ii) determining a first portion of the first sound recording and a second portion of the simultaneously recorded second sound recording, wherein the first portion and the second portion are covered by the diastolic period,
(iii) determining an adaptive filter for the first sound recording, wherein the adaptive filter is based on the first portion and the second portion and configured for reducing noise originating from the ambient background that is present in both the first sound recording and in the simultaneously recorded second sound recording, and
(iv) employing the adaptive filter to the first sound recording.

### Claim 14

An electronic stethoscope comprising:
(A) a first acoustic sensor configured to be placed on the chest of a person and for recording heartbeats,
(B) a second acoustic sensor configured to be placed at the person and for recording ambient background sounds,
(C) a processor operatively connected with the first acoustic sensor and the second acoustic sensor and configured to:
(a) obtain a first sound recordings with the first acoustic sensor, wherein the first recording is of a heartbeat of the person,
(b) obtain a second sound recording with the second acoustic sensor, wherein the second sound recording is of the ambient background surrounding the person and being recorded simultaneously to a first sound recording of the first plurality, and
(c) perform a filtering of the first sound recording by using the simultaneously recorded second sound, the filtering comprises:
(i) determining a diastolic period of the heartbeat of the first sound recording,
(ii) determining a first portion of the first sound recording and a second portion of the simultaneously recorded second sound recording, wherein the first portion and the second portion are covered by the diastolic period,
(iii) determining an adaptive filter for the first sound recording, wherein the adaptive filter is based on the first portion and the second portion and configured for reducing noise originating from the ambient background that is present in both the first sound recording and in the simultaneously recorded second sound recording, and
(iv) employing the adaptive filter to the first sound recording.