# US 11,998,751 B2 · Method and device for processing a cardiac signal

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- Number: US 11,998,751 B2
- Document ID: US11998751B2
- Status: Granted
- Kind: B2
- Application number: 17/110,904
- Filed: 2020-12-03
- Published: 2021-06-10
- Granted: 2024-06-04
- Earliest claimed: 2019-12-04
- Assignees: Sorin Crm SAS
- Applicants: Sorin Crm SAS
- Inventors: Elodie Marie; Luca Vitali
- Web page: https://patentgrep.com/patent/US11998751B2

## CPC

- A61B 5/352: Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
- A61N 1/3712: {Auto-capture, i.e. automatic adjustment of the stimulation threshold}
- A61B 5/287: Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
- A61B 5/29: for permanent or long-term implantation
- A61B 5/318: Heart-related electrical modalities, e.g. electrocardiography [ECG]
- A61B 5/361: Detecting fibrillation
- A61N 1/3956: {Implantable devices for applying electric shocks to the heart, e.g. for cardioversion}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B)

## Abstract

A method for processing a cardiac signal represented as a function of time includes providing a number n of different threshold levels Ni, with i=1 to n and n being greater than or equal to three; detecting, from a given time T and per threshold level Ni, at least two successive intersections of the cardiac signal with the threshold level Ni, considering a crossing per increasing and/or decreasing value of the cardiac signal with the threshold level Ni; and determining at least one statistical parameter for the cardiac signal from the intersections of the cardiac signal with the at least three different threshold levels Ni. The method may be implemented by a subcutaneous active implantable medical device having a control circuit configured to process a cardiac signal.

## Claims

### Claim 1

A method for processing a cardiac signal represented as a function of time, the method comprising:
providing a number n of different threshold levels Ni, with i=1 to n, and n being greater than or equal to three;
detecting, from a given time T and per threshold level Ni, at least two successive intersections of the cardiac signal with the different threshold levels Ni, considering a crossing per increasing and/or decreasing value of the cardiac signal with the threshold level Ni;
determining at least one statistical parameter for the cardiac signal from the at least two successive intersections of the cardiac signal with the at least three different threshold levels Ni, wherein determining the at least one statistical parameter comprises determining a period of the cardiac signal, and wherein the at least one statistical parameter is indicative of an arrhythamia; and
providing, based on the at least one statistical parameter, a defibrillation shock to a patient.

### Claim 2 (depends on 1)

The method of claim 1, wherein:
detecting the at least two successive intersections of the cardiac signal with the threshold level Ni further comprises determining, from the given time T and per threshold level Ni, at least one elapsed time Δ1ti, where i=1 to n, between the at least two successive intersections of the cardiac signal with the threshold level Ni; and
the at least one statistical parameter is determined in based on the at least one elapsed time Δ1ti.

### Claim 3 (depends on 2)

The method of claim 2, wherein:
a first elapsed time Δ1ti is determined per threshold level Ni between two most recent successive intersections from the given time T;
a second elapsed time Δ2ti is determined per threshold level Ni between a most recent intersection and a third most recent intersection from the given time T; and
the at least one statistical parameter for the cardiac signal is determined by comparing the first elapsed time Δ1ti with the second elapsed time Δ2ti.

### Claim 4 (depends on 3)

The method of claim 3, wherein the period of the cardiac signal from the given time T is determined based on a distribution by a number of the elapsed times (Δ1ti; Δ2ti).

### Claim 5 (depends on 4)

The method of claim 4, wherein the distribution by the number of the elapsed times (Δ1ti; Δ2ti) per defined time interval is represented via a histogram, and wherein the period of the cardiac signal from the given time T is determined from a mean or a median of the elapsed times (Δ1ti; Δ2ti) corresponding to a bar of the histogram that represents a largest number of occurrences of the elapsed times (Δ1ti; Δ2ti).

### Claim 6 (depends on 4)

The method of claim 4, wherein the distribution by number of the elapsed times (Δ1ti; Δ2ti) per defined time interval is represented by means of a histogram and wherein the period of the cardiac signal from the given time T is determined from a mean or a median of the elapsed times (Δ1ti; Δ2ti) comprised in a defined time interval that is greater than a time interval corresponding to that of one bar of the histogram.

### Claim 7 (depends on 3)

The method of claim 3, wherein only the elapsed times (Δ1ti; Δ2ti) for which a value crosses a predefined threshold are taken into account in the determination of the at least one statistical parameter.

### Claim 8 (depends on 7)

The method of claim 7, wherein the predefined threshold is determined from the detection of the at least two successive intersections of the cardiac signal with the threshold level Ni, at a time before the given time T.

### Claim 9 (depends on 1)

The method of claim 1, wherein providing the number n of different threshold levels Ni comprises determining a minimum amplitude and a maximum amplitude of the cardiac signal, such that values for the different threshold levels Ni are determined so that they are between a minimum value and a maximum value respectively corresponding to the minimum amplitude and the maximum amplitude of the cardiac signal.

### Claim 10 (depends on 1)

The method of claim 1, wherein a value for each of the different threshold levels Ni is constant over time.

### Claim 11 (depends on 1)

The method of claim 1, wherein a value for the different threshold levels Ni varies over time as a function of the at least one statistical parameter.

### Claim 12 (depends on 1)

The method of claim 1, wherein each of the different threshold levels Ni are spaced apart by a fixed interval.

### Claim 13 (depends on 1)

The method of claim 1, wherein providing a number n of different threshold levels Ni comprises providing at least ten different threshold levels Ni.

### Claim 14 (depends on 1)

The method of claim 1, wherein each of the different threshold levels Ni is different from a base line.

### Claim 15 (depends on 1)

The method of claim 1, wherein the cardiac signal is captured via an implantable lead of an active implantable medical device configured to capture cardiac signals subcutaneously.

### Claim 16 (depends on 1)

The method of claim 1, further comprising determining an interval between crossings of two successive threshold levels Ni=n and Ni=n+1 by the cardiac signal.

### Claim 17

A subcutaneous active implantable medical device comprising:
a housing;
a subcutaneous implantable lead connected to the housing and comprising one or more sensing electrodes configured to capture cardiac rhythms subcutaneously; and
a control circuit configured to:
provide a number n of different threshold levels Ni, with i=1 to n, and n being greater than or equal to three;
detect, from a given time T and for each of the different threshold levels Ni, at least two successive intersections of a cardiac signal with each of the different threshold levels Ni, wherein each of the at least two successive intersections indicate to a crossing of a threshold level Ni due to an increasing or decreasing value of the cardiac signal;
determine at least one statistical parameter for the cardiac signal from the at least two successive intersections of the cardiac signal with the different threshold levels Ni, wherein the determination of the at least one statistical parameter comprises determining a period of the cardiac signal, and wherein the at least one statistical parameter is indicative of an arrhythmia; and
provide, based on the at least one statistical parameter, a defibrillation shock to a patient.

### Claim 18 (depends on 17)

The device of claim 17, wherein:
detecting the at least two successive intersections of the cardiac signal with the threshold level Ni further comprises determining, from the given time T and for a particular threshold level Ni, at least one elapsed time Δ1ti, where i=1 to n, between the at least two successive intersections of the cardiac signal with the particular threshold level Ni; and
the at least one statistical parameter is determined in based on the at least one elapsed time Δ1ti.