Medical device and method for tachyarrythmia detection

Patent metadata

Field	Value
Publication number	US-11801385-B2
Application number	US-202017087960-A
Country	US
Kind code	B2
Filing date	Nov 3, 2020
Priority date	Nov 7, 2019
Publication date	Oct 31, 2023
Grant date	Oct 31, 2023

Abstract

A medical device is configured to determine time intervals between consecutive cardiac events sensed from a cardiac electrical signal, increase a value of a tachyarrhythmia interval count in response to each of the determine time intervals detected as a tachyarrhythmia interval. The device is further configured to detect normal sinus rhythm events and the decrease the value of the tachyarrhythmia interval count in response to a threshold number of detected normal sinus rhythm events.

First claim

What is claimed is:

1. A medical device comprising:
a cardiac electrical signal sensing circuit configured to:
receive a first cardiac electrical signal;
sense cardiac events from the first cardiac electrical signal;

a control circuit configured to:
determine time intervals between consecutive cardiac events sensed from the first cardiac electrical signal;
detect a plurality of tachyarrhythmia intervals from the determined time intervals, each of the plurality of tachyarrhythmia intervals being less than a tachyarrhythmia detection interval threshold;
increase a value of a tachyarrhythmia interval count in response to detecting each of the plurality of tachyarrhythmia intervals;
detect a normal sinus rhythm interval from the determined time intervals, the normal sinus rhythm interval being greater than a normal sinus rhythm interval threshold;
increase a normal sinus rhythm interval count in response to detecting the normal sinus rhythm interval;
compare the normal sinus rhythm interval count to a first reset threshold number of normal sinus rhythm intervals;
determine that the first reset threshold number of normal sinus rhythm intervals are detected based on the comparing of the normal sinus rhythm interval count to the first reset threshold number of normal sinus rhythm intervals;
decrease the value of the tachyarrhythmia interval count in response to the first reset threshold number of normal sinus rhythm intervals being detected; and
after decreasing the value of the tachyarrhythmia interval count, determine that the tachyarrhythmia interval count subsequently reaches a tachyarrhythmia detection threshold; and
detect a tachyarrhythmia in response to the value of the tachyarrhythmia interval count reaching the tachyarrhythmia detection threshold; and

a therapy delivery circuit configured to deliver a tachyarrhythmia therapy in response to the control circuit detecting the tachyarrhythmia.

2. The device of claim 1 wherein the control circuit is further configured to detect the normal sinus rhythm interval by:
setting a long interval threshold;
detecting a plurality of long intervals from the determined time intervals, each one of the plurality of long intervals being greater than the long interval threshold;
determining the normal sinus rhythm interval threshold based on the plurality of long intervals; and
detecting the normal sinus rhythm interval in response to a time interval determined between the consecutive cardiac events sensed from the first cardiac electrical signal being greater than the determined normal sinus rhythm interval threshold.

3. The device of claim 2 , wherein the control circuit is configured to:
set the long interval threshold to an interval that is a predetermined interval longer than the tachyarrhythmia detection interval.

4. The device of claim 1 , wherein:
the control circuit is further configured to determine that the first reset threshold number of normal sinus rhythm intervals are detected by:
determining that a first threshold number of normal sinus rhythm intervals are detected out of a first predetermined number of sensed cardiac events; and
determining that a second threshold number of normal sinus rhythm intervals are detected out of a second predetermined number of sensed cardiac events,
wherein the first predetermined number of sensed cardiac events is greater than the second predetermined number of sensed cardiac events and includes the second predetermined number of cardiac events.

5. The device of claim 1 , wherein:
the cardiac electrical signal sensing circuit is further configured to sense a second cardiac electrical signal different than the first cardiac electrical signal;
the control circuit is further configured to:
detect a normal sinus rhythm morphology from the second cardiac electrical signal corresponding to a time of a cardiac event sensed from the first cardiac electrical signal at the detected normal sinus rhythm interval;
detect a normal sinus rhythm beat associated with the normal sinus rhythm interval based on the detected normal sinus rhythm morphology; and
determine that the first reset threshold number of normal sinus rhythm intervals are detected in response to detecting a normal sinus rhythm beat associated with each of the first reset threshold number of normal sinus rhythm intervals.

6. The device of claim 5 , wherein the control circuit is configured to detect the normal sinus rhythm morphology by:
determining a morphology matching score between the second cardiac electrical signal and a predetermined normal sinus rhythm template;
determining that the morphology matching score is greater than a match threshold;
determining a plurality of beat features from a first time interval of the second cardiac electrical signal, the first time interval comprising a time point of the cardiac event sensed from the first cardiac electrical signal;
determining that the plurality of beat features meet beat feature matching criteria; and
detect the normal sinus rhythm morphology in response to determining that the morphology matching score is greater than the match threshold and the plurality of beat features meet the beat feature matching criteria.

7. The device of claim 6 , wherein the control circuit is further configured to set at least one of the match threshold and a threshold of the beat feature matching criteria based on the first reset threshold.

8. The device of claim 6 , wherein the control circuit is configured to detect the plurality of beat features by determining one or more of:
a polarity pattern of signal peaks of the second cardiac electrical signal over the first time interval;
a peak time interval from a reference time point to a maximum peak amplitude during the first time interval; or
a normalized width metric determined by summing all sample point amplitudes of the second cardiac electrical signal over the first time interval and dividing by the maximum peak amplitude.

9. The device of claim 1 , wherein the control circuit is further configured to:
determine that the tachyarrhythmia interval count is greater than a second reset threshold number of tachyarrhythmia intervals;
decrease the value of the tachyarrhythmia interval count in response to the tachyarrhythmia interval count being greater than the second reset threshold and the first reset threshold number of normal sinus rhythm beats being detected; and
decrease the value of the tachyarrhythmia interval count to a value greater than zero and less than the second reset threshold.

10. The device of claim 1 , wherein the control circuit is further configured to:
determine a current value of the tachyarrhythmia interval count in response to the first reset threshold number of normal sinus rhythm intervals being detected; and
decrease the value of the tachyarrhythmia interval count to an adjusted value that is based on the current value of the tachyarrhythmia interval count.

11. The device of claim 1 , wherein the control circuit is further configured to set the first reset threshold based on the tachyarrhythmia detection threshold.

12. The device of claim 1 , wherein:
the sensing circuit is further configured to sense a second cardiac electrical signal different than the first cardiac electrical signal; and
the control circuit is further configured to:
determine at least one gross morphology metric from the second cardiac electrical signal over a gross morphology time interval, the gross morphology time interval comprising a time point of a cardiac event sensed from the first cardiac electrical signal associated with the detected normal sinus rhythm interval;
determine that the at

Assignees

• Medtronic Inc

Inventors

• Zhang Xusheng
• Dehmer Kevin L
• Greenhut Saul
• Jackson Troy E
• Liu Yuanzhen

Classifications

• A61N1/3621 Primary

  for treating or preventing abnormally high heart rate · CPC title

• A61B5/363

  Detecting tachycardia or bradycardia · CPC title

• A61N1/3925 Primary

  Monitoring; Protecting · CPC title

• A61N1/36592

  controlled by the heart rate variability · CPC title

• A61B5/686

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