# US 12,569,184 B2 · Cardiac electrical signal gross morphology-based noise detection for rejection of ventricular tachyarrhythmia detection

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- Number: US 12,569,184 B2
- Document ID: US12569184B2
- Status: Granted
- Kind: B2
- Application number: 18/735,157
- Filed: 2024-06-05
- Published: 2024-09-26
- Granted: 2026-03-10
- Earliest claimed: 2016-07-27
- Assignees: Medtronic, Inc.
- Applicants: Medtronic, Inc.
- Inventors: Xusheng Zhang; Jian Cao; Saul E. Greenhut
- Web page: https://patentgrep.com/patent/US12569184B2

## CPC

- A61B 5/363: Detecting tachycardia or bradycardia
- A61B 5/02108: {from analysis of pulse wave characteristics}
- A61B 5/341: Vectorcardiography [VCG]
- A61B 5/349: Detecting specific parameters of the electrocardiograph cycle
- A61B 5/352: Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
- A61B 5/7203: {for noise prevention, reduction or removal}
- A61N 1/3621: {for treating or preventing abnormally high heart rate}
- A61N 1/365: controlled by a physiological parameter, e.g. heart potential {(evoked response A61N1/371)}
- A61N 1/3702: {Physiological parameters (A61N1/365 takes precedence; evoked response A61N1/371)}
- A61N 1/3925: {Monitoring; Protecting}
- A61B 5/0245: by using sensing means generating electric signals, {i.e. ECG signals}
- A61B 5/4836: {Diagnosis combined with treatment in closed-loop systems or methods (A61B5/0036 takes precedence)}
- A61N 1/3704: {Circuits specially adapted therefor, e.g. for sensitivity control}
- A61N 1/3956: {Implantable devices for applying electric shocks to the heart, e.g. for cardioversion}
- A61N 1/3962: {in combination with another heart therapy}
- A61N 1/3987: {characterised by the timing or triggering of the shock}
- H03H 21/0012: {Digital adaptive filters}
- 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)
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)

## Abstract

A medical device system, such as an extra-cardiovascular implantable cardioverter defibrillator ICD, senses R-waves from a first cardiac electrical signal by a first sensing channel and stores a time segment of a second cardiac electrical signal in response to each sensed R-wave. The medical device system determines a morphology parameter correlated to signal noise from time segments of the second cardiac electrical signal, detects a noisy signal segment based on the signal morphology parameter; and withholds detection of a tachyarrhythmia episode in response to detecting a threshold number of noisy signal segments.

## Claims

### Claim 1

A medical device, comprising:
a sensing circuit configured to:
sense one or more cardiac electrical signals; and
sense R-waves from the one or more cardiac electrical signals;
a control circuit coupled to the sensing circuit, the control circuit configured to:
obtain a signal segment from the one or more cardiac electrical signals sensed by the sensing circuit in response to one R-wave sensed by the sensing circuit by determining a differential signal from the one or more cardiac electrical signals sensed by the sensing circuit;
determine a noise pulse amplitude threshold from the signal segment;
determine a noise pulse count from the signal segment using the noise pulse amplitude threshold;
determine that the noise pulse count meets a noisy segment threshold;
determine that the signal segment is a noisy signal segment in response to the noise pulse count meeting the noisy segment threshold; and
in response to at least determining that the signal segment is a noisy signal segment, withhold detecting a tachyarrhythmia from the one or more cardiac electrical signals.

### Claim 2 (depends on 1)

The medical device of claim 1 wherein the control circuit is further configured to obtain the signal segment in response to one R-wave sensed by the sensing circuit by obtaining a first specified number of cardiac electrical signal sample points preceding the one R-wave and obtaining a second specified number of cardiac electrical signal sample points following the one R-wave.

### Claim 3 (depends on 2)

The medical device of claim 2 wherein the control circuit is further configured to obtain the first specified number of cardiac electrical signal sample points as a higher number of sample points than the second specified number of cardiac electrical signal sample points.

### Claim 4 (depends on 1)

The medical device of claim 1 wherein the control circuit is further configured to:
determine a plurality of intervals between the R-waves sensed by the sensing circuit;
determine that at least a threshold number of the plurality of intervals are less than a tachyarrhythmia detection interval; and
determine the noise pulse count from the signal segment in response to at least the threshold number of the plurality of intervals being less than the tachyarrhythmia detection interval.

### Claim 5 (depends on 1)

The medical device of claim 1 wherein the control circuit is further configured to determine the noise pulse amplitude threshold by:
determining a maximum amplitude of the signal segment; and
determining the noise pulse amplitude threshold as a portion of the maximum amplitude of the signal segment.

### Claim 6 (depends on 1)

The medical device of claim 1 wherein the control circuit is further configured to determine the noise pulse count from the signal segment using the noise pulse amplitude threshold by:
demarking zero crossings of the signal segment;
comparing the noise pulse amplitude threshold to sample point amplitudes of the signal segment; and
identifying a signal pulse between a pair of consecutive zero crossings of the demarked zero crossings by determining that the noise pulse amplitude threshold is met by a sample point amplitude of the signal segment between the pair of consecutive zero crossings; and
counting each identified signal pulse in the signal segment in the noise pulse count.

### Claim 7 (depends on 1)

The medical device of claim 1 further comprising:
a memory configured to store a pulse width threshold; and
wherein the control circuit is further configured to determine the noise pulse count from the signal segment using the noise pulse amplitude threshold and the pulse width threshold for identifying signal pulses in the signal segment.

### Claim 8 (depends on 7)

The medical device of claim 7 wherein the control circuit is further configured to determine the noise pulse count from the signal segment by:
demarking zero crossings of the signal segment;
comparing the noise pulse amplitude threshold to sample point amplitudes of the signal segment;
identifying a signal pulse by:
determining that the noise pulse amplitude threshold is met by a sample point amplitude of the signal segment between a pair of consecutive zero crossings of the demarked zero crossings; and
determining that the pair of consecutive zero crossings are at least the pulse width threshold apart; and
counting each identified signal pulse in the signal segment in the noise pulse count.

### Claim 9 (depends on 1)

The medical device of claim 1 further comprising:
a therapy delivery circuit configured to deliver an anti-tachyarrhythmia therapy; and
wherein the control circuit is further configured to:
detect a tachyarrhythmia rate from the R-waves sensed by the sensing circuit;
for each one of a plurality of sensed R-waves, obtain a signal segment from the one or more cardiac electrical signals;
determine a noise pulse count from each of the obtained signal segments;
determine, based on the noise pulse counts, if a threshold number of the obtained signal segments are noisy signal segments;
detect a tachyarrhythmia episode in response to detecting the tachyarrhythmia rate and determining that less than the threshold number of the obtained signal segments are noisy signal segments; and
withhold detecting the tachyarrhythmia episode in response to detecting the tachyarrhythmia rate and determining that at least the threshold number of the obtained signal segments are noisy signal segments;
control the therapy delivery circuit to deliver the anti-tachyarrhythmia therapy in response to detecting the tachyarrhythmia episode and
control the therapy delivery circuit to not deliver the anti-tachyarrhythmia therapy in response to withholding detecting the tachyarrhythmia episode.

### Claim 10

A method comprising:
sensing one or more cardiac electrical signals;
sensing R-waves from the one or more cardiac electrical signals;
obtaining a signal segment from the one or more cardiac electrical signals in response to one sensed R-wave, wherein obtaining the signal segment comprises determining a differential signal from the one or more sensed cardiac electrical signals;
determining a noise pulse amplitude threshold from the signal segment;
determining a noise pulse count from the signal segment using the noise pulse amplitude threshold;
determining that the noise pulse count meets a noisy segment threshold;
determining that the signal segment is a noisy signal segment in response to the noise pulse count meeting the noisy segment threshold; and
in response to at least determining that the signal segment is a noisy signal segment, withholding detecting a tachyarrhythmia from the one or more cardiac electrical signals.

### Claim 11 (depends on 10)

The method of claim 10 wherein obtaining the signal segment in response to one sensed R-wave comprises obtaining a first specified number of cardiac electrical signal sample points preceding the one R-wave and obtaining a second specified number of cardiac electrical signal sample points following the one R-wave.

### Claim 12 (depends on 11)

The method of claim 11 further comprising obtaining the first specified number of cardiac electrical signal sample points as a higher number of sample points than the second specified number of cardiac electrical signal sample points.

### Claim 13 (depends on 10)

The method of claim 10 further comprising:
determining a plurality of intervals between the sensed R-waves;
determining that at least a threshold number of the plurality of intervals are less than a tachyarrhythmia detection interval; and
determining the noise pulse count from the signal segment in response to at least the threshold number of the plurality of intervals being less than the tachyarrhythmia detection interval.

### Claim 14 (depends on 10)

The method of claim 10 wherein determining the noise pulse amplitude threshold comprises:
determining a maximum amplitude of the signal segment; and
determining the noise pulse amplitude threshold as a portion of the maximum amplitude of the signal segment.

### Claim 15 (depends on 10)

The method of claim 10 wherein determining the noise pulse count from the signal segment using the noise pulse amplitude threshold comprises:
demarking zero crossings of the signal segment;
comparing the noise pulse amplitude threshold to sample point amplitudes of the signal segment; and
identifying a signal pulse between a pair of consecutive zero crossings of the demarked zero crossings by determining that the noise pulse amplitude threshold is met by a sample point amplitude of the signal segment between the pair of consecutive zero crossings; and
counting each identified signal pulse in the signal segment in the noise pulse count.

### Claim 16 (depends on 10)

The method of claim 10 further comprising:
storing a pulse width threshold; and
determining the noise pulse count from the signal segment using the noise pulse amplitude threshold and the pulse width threshold for identifying signal pulses in the signal segment.

### Claim 17 (depends on 16)

The method of claim 16 wherein determining the noise pulse count from the signal segment comprises:
demarking zero crossings of the signal segment;
comparing the noise pulse amplitude threshold to sample point amplitudes of the signal segment;
identifying a signal pulse by:
determining that the noise pulse amplitude threshold is met by a sample point amplitude of the signal segment between a pair of consecutive zero crossings of the demarked zero crossings; and
determining that the pair of consecutive zero crossings are at least the pulse width threshold apart; and
counting each identified signal pulse in the signal segment in the noise pulse count.

### Claim 18 (depends on 10)

The method of claim 10 further comprising:
detecting a tachyarrhythmia rate from the sensed R-waves;
for each one of a plurality of sensed R-waves, obtaining a signal segment from the one or more cardiac electrical signals;
determining a noise pulse count from each of the obtained signal segments;
determining based on the noise pulse counts, if a threshold number of the obtained signal segments are noisy signal segments;
detecting a tachyarrhythmia episode in response to detecting the tachyarrhythmia rate and determining that less than the threshold number of the obtained signal segments are noisy signal segments;
withholding detecting the tachyarrhythmia episode in response to detecting the tachyarrhythmia rate and determining that at least the threshold number of the obtained signal segments are noisy signal segments;
delivering an anti-tachyarrhythmia therapy in response to detecting the tachyarrhythmia episode and
not delivering the anti-tachyarrhythmia therapy in response to withholding detecting the tachyarrhythmia episode.

### Claim 19

A non-transitory computer readable medium storing instructions that, when executed by a control circuit of a medical device, cause the medical device to:
sense one or more cardiac electrical signals;
sense R-waves from the one or more cardiac electrical signals;
obtain a signal segment from the one or more cardiac electrical signals in response to one sensed R-wave, wherein obtaining the signal segment comprises determining a differential signal from the one or more sensed cardiac electrical signals;
determine a noise pulse amplitude threshold from the signal segment;
determine a noise pulse count from the signal segment using the noise pulse amplitude threshold;
determine that the noise pulse count meets a noisy segment threshold;
determine that the signal segment is a noisy signal segment in response to the noise pulse count meeting the noisy segment threshold; and
in response to at least determining that the signal segment is a noisy signal segment, withhold detecting a tachyarrhythmia from the one or more cardiac electrical signals.