# US 12,004,863 B2 · Cardiac electrical signal gross morphology-based noise detection for rejection of ventricular tachyarrhythmia detection

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- Number: US 12,004,863 B2
- Document ID: US12004863B2
- Status: Granted
- Kind: B2
- Application number: 17/732,461
- Filed: 2022-04-28
- Published: 2022-08-11
- Granted: 2024-06-11
- 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/US12004863B2

## 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 at least one cardiac electrical signal; and
sense R-waves from the at least one cardiac electrical signal;
a control circuit coupled to the sensing circuit, the control circuit configured to:
obtain a signal segment from the at least one cardiac electrical signal sensed by the sensing circuit in response to one R-wave sensed by the sensing circuit, the signal segment extending a first time interval earlier than the one R-wave sensed by the sensing circuit;
determine a morphology parameter from the signal segment;
determine that the signal segment is a noisy signal segment based on the morphology parameter; and
in response to at least determining that the signal segment is a noisy signal segment, withhold a detection of a tachyarrhythmia episode.

### Claim 2 (depends on 1)

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

### Claim 3 (depends on 1)

The medical device of claim 1, wherein the control circuit is further configured to determine the morphology parameter from the signal segment by:
identifying one or more signal pulses occurring during the signal segment; and
determining a count of the identified one or more signal pulses.

### Claim 4 (depends on 1)

The medical device of claim 1, wherein the control circuit is further configured to:
determine when the signal segment is a potential shockable beat based on the signal segment; and
determine that the signal segment is a noisy signal segment by one of:
determining that the morphology parameter is greater than a first noisy segment threshold when the signal segment is determined to be a potential shockable beat; or
determining that the morphology parameter is greater than a second noisy segment threshold determine when the signal segment is determined to not be a potential shockable beat, wherein the second noisy segment threshold is less than the first noisy segment threshold.

### Claim 5 (depends on 4)

Medical device of claim 4, wherein the control circuit is further configured to determine when the signal segment is a potential shockable beat based on the signal segment by:
determining from the signal segment a signal width parameter;
determine if the signal width parameter is greater than a potential shockable beat threshold width; and
determine that the signal segment is a potential shockable beat in response to at least the signal width parameter being greater than the potential shockable beat threshold width.

### Claim 6 (depends on 4)

The medical device of claim 4, wherein the control circuit is further configured to determine when the signal segment is a potential shockable beat based on the signal segment by:
determining from the signal segment a signal amplitude parameter;
determine if the signal amplitude parameter is greater than a potential shockable beat threshold amplitude; and
determine that the signal segment is a potential shockable beat in response to at least the signal amplitude parameter being greater than the potential shockable beat threshold amplitude.

### Claim 7 (depends on 6)

The medical device of claim 6, wherein the control circuit is further configured to determine the signal amplitude parameter by:
determining a summation of sample point amplitudes of the signal segment; and
normalizing the summation by a maximum sample point amplitude of the time segment.

### Claim 8 (depends on 1)

The medical device of claim 1, wherein the control circuit is further configured to:
increase a count of noisy signal segments in response to detecting the noisy signal segment;
determine a plurality of intervals between the R-waves from the at least one cardiac electrical signal;
determine that a threshold number of the plurality of intervals are less than a tachyarrhythmia detection interval;
compare a value of the count of noisy signal segments to a rejection threshold in response to determining that the threshold number of the plurality of intervals are less than the tachyarrhythmia detection interval, and
withhold the detection of the tachyarrhythmia episode in response to the value of the count of noisy signal segments being equal to or greater than the rejection threshold.

### Claim 9 (depends on 1)

The medical device of claim 1, further comprising a therapy delivery circuit, wherein:
the control circuit is further configured to:
obtain a second signal segment from the at least one cardiac electrical signal sensed by the sensing circuit in response to a second R-wave sensed by the sensing circuit;
determine that the second signal segment is not a noisy segment; and
in response to determining that at least the second signal segment is not a noisy signal segment, detect the tachyarrhythmia episode based on the at least one cardiac electrical signal; and
the therapy delivery circuit is configured to deliver an anti-tachyarrhythmia therapy in response to the control circuit detecting the tachyarrhythmia episode.

### Claim 10 (depends on 9)

The medical device of claim 9, wherein the therapy delivery circuit is further configured to deliver the anti-tachyarrhythmia therapy via an electrode vector that is implanted outside a patient's heart.

### Claim 11 (depends on 1)

The medical device of claim 1 wherein the control circuit is further configured to obtain the signal segment extending the first time interval earlier than the one R-wave and extending a second time interval later than the one R-wave, wherein the first time interval is longer than the second time interval.

### Claim 12

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 at least one cardiac electrical signal;
sense R-waves from the at least one cardiac electrical signal;
obtain a signal segment from the at least one cardiac electrical signal in response to one sensed R-wave, the signal segment extending a first time interval earlier than the one sensed R-wave;
determine a morphology parameter from the signal segment;
determine that the signal segment is a noisy signal segment based on the morphology parameter; and
in response to determining that the signal segment is a noisy signal segment, withhold a detection of a tachyarrhythmia episode.

### Claim 13 (depends on 12)

The non-transitory computer readable medium of claim 12, further comprising instructions that cause the medical device to:
determine a plurality of intervals between the sensed R-waves;
determine that at least a threshold number of the plurality of intervals are less than a tachyarrhythmia detection interval; and
determine the morphology parameter of 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 12)

The non-transitory computer readable medium of claim 12, further comprising instructions that cause the medical device to determine the morphology parameter from the signal segment by:
identifying one or more signal pulses occurring during the signal segment; and
determining a count of the identified one or more signal pulses.

### Claim 15 (depends on 12)

The non-transitory computer readable medium of claim 12, further comprising instructions that cause the medical device to:
determine when the signal segment is a potential shockable beat based on the signal segment; and
determine that the signal segment is a noisy signal segment by one of:
determining that the morphology parameter is greater than a first noisy segment threshold when the signal segment is determined to be a potential shockable beat; or
determining that the morphology parameter is greater than a second noisy segment threshold determine when the signal segment is determined to not be a potential shockable beat, wherein the second noisy segment threshold is less than the first noisy segment threshold.

### Claim 16 (depends on 15)

The non-transitory computer readable medium of claim 15, further comprising instructions that cause the medical device to determine when the signal segment is a potential shockable beat based on the signal segment by:
determining from the signal segment a signal width parameter;
determine if the signal width parameter is greater than a potential shockable beat threshold width; and
determine that the signal segment is a potential shockable beat in response to at least the signal width parameter being greater than the potential shockable beat threshold width.

### Claim 17 (depends on 15)

The non-transitory computer readable medium of claim 15, further comprising instructions that cause the medical device to determine when the signal segment is a potential shockable beat based on the signal segment by:
determining from the signal segment a signal amplitude parameter;
determine if the signal amplitude parameter is greater than a potential shockable beat threshold amplitude; and
determine that the signal segment is a potential shockable beat in response to at least the signal amplitude parameter being greater than the potential shockable beat threshold amplitude.

### Claim 18 (depends on 17)

The non-transitory computer readable medium of claim 17, further comprising instructions that cause the medical device to determine the signal amplitude parameter by:
determining a summation of sample point amplitudes of the signal segment; and
normalizing the summation by a maximum sample point amplitude of the time segment.

### Claim 19 (depends on 12)

The non-transitory computer readable medium of claim 12, further comprising instructions that cause the medical device to:
increase a count of noisy signal segments in response to detecting the noisy signal segment;
determine a plurality of intervals between the R-waves from the at least one cardiac electrical signal;
determine that a threshold number of the plurality of intervals are less than a tachyarrhythmia detection interval;
compare a value of the count of noisy signal segments to a rejection threshold in response to determining that the threshold number of the plurality of intervals are less than the tachyarrhythmia detection interval, and
withhold the detection of the tachyarrhythmia episode in response to the value of the count of noisy signal segments being equal to or greater than the rejection threshold.

### Claim 20 (depends on 12)

The non-transitory computer readable medium of claim 12, further comprising instructions that cause the medical device to:
obtain a second signal segment from the at least one cardiac electrical signal in response to a second sensed R-wave;
determine that the second signal segment is not a noisy segment; and
in response to determining that at least the second signal segment is not a noisy signal segment, detect the tachyarrhythmia episode based on the at least one cardiac electrical signal; and
deliver an anti-tachyarrhythmia therapy in response to detecting the tachyarrhythmia episode.

### Claim 21

A method comprising:
sensing by a sensing circuit of a medical device at least one cardiac electrical signal;
sensing by the sensing circuit R-waves from the at least one cardiac electrical signal;
obtaining by a control circuit of the medical device a signal segment from the at least one cardiac electrical signal in response to one sensed R-wave, the signal segment extending a predetermined time interval earlier than the one sensed R-wave;
determining by the control circuit a morphology parameter from the signal segment;
determining by the control circuit that the signal segment is a noisy signal segment based on the morphology parameter; and
in response to determining that the signal segment is a noisy signal segment, withholding a detection of a tachyarrhythmia episode.