Method and apparatus for detecting cardiac event oversensing

Patent metadata

Field	Value
Publication number	US-2021170170-A1
Application number	US-202017109968-A
Country	US
Kind code	A1
Filing date	Dec 2, 2020
Priority date	Dec 9, 2019
Publication date	Jun 10, 2021
Grant date	—

Abstract

A medical device is configured to detect an alternating pattern of signal features determined from consecutive segments of a cardiac electrical signal and determine a gross morphology metric from at least one segment of the cardiac electrical signal. The device is configured to detect cardiac event oversensing in response to detecting the alternating pattern and the gross morphology metric not meeting tachyarrhythmia morphology criteria. The medical device may withhold detecting an arrhythmia in response to detecting the cardiac event oversensing.

First claim

What is claimed is:

1 . A medical device comprising:
a cardiac electrical signal sensing circuit configured to:
sense at least one cardiac electrical signal;
detect cardiac events from the at least one cardiac electrical signal;
a control circuit configured to:
in response to each one of a plurality of cardiac events detected from the at least one cardiac electrical signal, determine a signal feature from a segment of the at least one cardiac electrical signal;
detect an alternating pattern of the signal feature determined from consecutive segments of the at least one cardiac electrical signal;
determine a gross morphology metric from each of at least one segment of the consecutive segments;
determine that the gross morphology metric does not meet a tachyarrhythmia morphology criteria;
detect cardiac event oversensing in response to the gross morphology metric not meeting the tachyarrhythmia morphology criteria and detecting the alternating pattern; and
withhold detection of an arrhythmia in response to detecting the cardiac event oversensing.

2 . The medical device of claim 1 , wherein the control circuit is further configured to:
in response to detecting the alternating pattern, identify at least one segment of the at least one cardiac electrical signal corresponding to a suspected true sensed cardiac event based on the alternating pattern; and determine the gross morphology metric from the at least one segment corresponding to the suspected true sensed cardiac event.

3 . The medical device of claim 1 , wherein the control circuit is further configured to detect tachyarrhythmia based on the cardiac events detected from the at least one cardiac electrical signal meeting a tachyarrhythmia criteria;
the medical device further comprising a therapy delivery circuit configured to generate a therapy in response to the control circuit detecting tachyarrhythmia.

4 . The medical device of claim 1 , wherein:
the control circuit is further configured to:
detect evidence of a tachyarrhythmia morphology in response to the gross morphology metric determined from each of at least one segment of the consecutive segments meeting the tachyarrhythmia morphology criteria; and
withhold the cardiac event oversensing in response to detecting the alternating pattern when the gross morphology metric from at least one of the consecutive segments meets the tachyarrhythmia morphology criteria.

5 . The medical device of claim 1 , wherein the control circuit is configured to detect the alternating pattern of the signal features by:
determining a first signal feature from a first signal segment of the at least one cardiac electrical signal, a second signal feature from a second signal segment of the at least one cardiac electrical signal and a third signal feature from a third signal segment of the at least one cardiac electrical signal, the first, second and third signal segments corresponding to first, second and third cardiac events, respectively, detected consecutively from the at least one cardiac electrical signal; setting a first difference threshold based on one of the first signal feature or the second signal feature; determining a first difference between the first signal feature and the second signal feature; determining that the first difference is greater than the first difference threshold; setting a second difference threshold based on one of the second signal feature or the third signal feature; determining a second difference between the second signal feature and the third signal feature; determining that the second difference is greater than the second difference threshold; and detecting the alternating pattern in response to the first difference being greater than the first difference threshold and the second difference being greater than the second difference threshold.

6 . The medical device of claim 5 , wherein the control circuit is configured to determine each of the first signal feature, the second signal feature and the third signal feature by determining a first maximum peak-to-peak amplitude, a second maximum peak-to-peak amplitude, and a third maximum peak-to-peak amplitude from the first, second, and third signal segments, respectively.

7 . The medical device of claim 5 , wherein the control circuit is further configured to:
determine a third difference between the first signal feature and the third signal feature; determine that the third difference is less than a stability threshold; and detect the alternating pattern of the signal features based on the first and second differences being greater than the first and second difference thresholds, respectively, and the third difference being less than the stability threshold.

8 . The medical device of claim 1 , wherein the control circuit is configured to detect the alternating pattern of the signal features by detecting an alternating pattern of at least one of a peak-to-peak amplitude, a cardiac event interval, or a polarity of a maximum peak amplitude.

9 . The medical device of claim 1 , wherein the control circuit is configured to determine the gross morphology metric by:
determining a maximum amplitude of the segment; determining a summation of a plurality of sample point amplitudes of the segment; and dividing the summation by the maximum amplitude.

10 . The medical device of claim 1 , wherein the control circuit is configured to determine the gross morphology metric by:
identifying a plurality of signal pulses of the segment; determining a signal width of each of the plurality of signal pulses; and determine a maximum signal width out of the determined signal widths.

11 . The medical device of claim 1 , wherein the control circuit is further configured to:
determine a first gross morphology metric by determining a gross morphology amplitude metric; determine a second gross morphology metric by determining a gross morphology signal width metric; determine that the gross morphology amplitude metric is less than or equal to a first threshold; determine that the gross morphology signal width metric is less than or equal to a second threshold; verify a suspected true sensed cardiac event in response to both the gross morphology amplitude metric being less than or equal to the first threshold and the gross morphology signal width metric being less than or equal to the second threshold; and detect the cardiac event oversensing in response to detecting the alternating pattern and verifying the suspected true sensed cardiac event.

12 . The medical device of claim 1 , wherein the control circuit is further configured to:
detect evidence of oversensing by detecting an alternating pattern of the signal features during a predetermined number of the consecutive segments; determine that the evidence of oversensing has been detected a threshold number of times, wherein the threshold number of times is a proportion of a number of cardiac event intervals between consecutively detected cardiac events from the at least one cardiac electrical signal required to detect the arrhythmia; and detect the cardiac event oversensing in response to determining that the evidence of oversensing has been detected the threshold number of times.

13 . The medical device of claim 12 , wherein the control circuit is configured to adjust the threshold number of times in response to a change in the number of cardiac event intervals required to detect the arrhythmia.

14 . The medical device of claim 1 , wherein:
the sensing circuit is configured to:
sense a first cardiac electrical signal of the at least one cardiac electrical s

Assignees

• Medtronic Inc

Inventors

• Mischler Gavin M
• Liu Yuanzhen
• Greenhut Saul E
• Zhang Xusheng

Classifications

• A61B5/363

  Detecting tachycardia or bradycardia · CPC title

• A61B5/7282

  Event detection, e.g. detecting unique waveforms indicative of a medical condition (cough events A61B5/0823; seizures A61B5/4094; sleep apnoea A61B5/4818) · CPC title

• A61N1/3956

  Implantable devices for applying electric shocks to the heart, e.g. for cardioversion · CPC title

• A61B5/7221

  Determining signal validity, reliability or quality (preventing, reducing or removing noise induced by motion artefacts A61B5/7207; noise originating from a therapeutic or surgical apparatus A61B5/7217) · CPC title

• A61B5/686

  Permanently implanted devices, e.g. pacemakers, other stimulators, biochips (A61B5/6861 takes precedence) · CPC title