R-R interval pattern recognition for use in arrhythmia discrimination

Patent metadata

Field	Value
Publication number	US-12150770-B2
Application number	US-202318191452-A
Country	US
Kind code	B2
Filing date	Mar 28, 2023
Priority date	May 4, 2020
Publication date	Nov 26, 2024
Grant date	Nov 26, 2024

Abstract

Described herein are methods, devices, and systems that improve arrhythmia episode detection specificity, such as, but not limited to, atrial fibrillation (AF) episode detection specificity. Such a method can include obtaining an ordered list of R-R intervals within a window leading up to a detection of a potential arrhythmia episode, determining a measure of a dominant repeated R-R interval pattern within the window, and comparing the measure of the dominant repeated R-R interval pattern to a pattern threshold. If the measure of the dominant repeated R-R interval pattern is below the pattern threshold, that is indicative of a regularly irregular pattern being present, and there is a determination that the detection of the potential arrhythmia episode does not correspond to an actual arrhythmia episode. Such embodiments can beneficially be used to significantly reduce the number of false positive arrhythmia detections.

First claim

What is claimed is:

1. An implantable medical device (IMD), comprising:
a plurality of electrodes;
a sensing circuit coupled to one or more of the electrodes and configured to obtain a signal indicative of electrical activity of a patient's heart;
a therapy circuit coupled to one or more of the electrodes and configured to deliver therapy to the patient's heart;
at least one of a processor or controller; and
a battery configured to provide power to the sensing circuit, the therapy circuit and to the at least one of the processor or controller;
the at least one of the processor or controller configured to
detect a potential arrhythmia episode;
obtain an ordered list of R-R intervals within a window leading up to the detection of the potential arrhythmia episode, wherein each of the R-R intervals has a respective duration;
determine, based on the ordered list of R-R intervals within the window, pairwise differences between pairs of the R-R intervals that are various different intervals apart, to thereby produce a plurality of sets of pairwise differences;
determine, based on the plurality of sets of pairwise differences, a measure of a dominant repeated R-R interval pattern;
compare the measure of the dominant repeated R-R interval pattern to a pattern threshold; and
classify the detection of the potential arrhythmia episode as a false positive, when the measure of the dominant repeated R-R interval pattern is below the pattern threshold, and in response thereto, prevent the therapy circuit from delivering therapy to the patient's heart.

2. The IMD of claim 1 , wherein the at least one of the processor or controller is configured to:
for each set of pairwise intervals, of the plurality of sets of pairwise intervals, determine a median of the set or an indicator of the median, to thereby produce a plurality of medians or indicators of medians; and
determine the measure of the dominant repeated R-R interval pattern within the window by determining a minimum of the plurality of medians or indicators of the medians.

3. The IMD of claim 1 , wherein the potential arrhythmia episode comprises a potential atrial fibrillation (AF) episode.

4. The IMD of claim 1 , wherein:
the IMD comprises an implantable cardioverter defibrillator (ICD);
the therapy circuit comprises a shocking circuit; and
the at least one of the processor or controller is configured to classify the detection of the potential arrhythmia episode as a false positive, when the measure of the dominant repeated R-R interval pattern is below the pattern threshold, and in response thereto, prevent the shocking circuit from delivering a shock to the patient's heart.

5. The IMD of claim 1 , wherein the IMD comprises a pacemaker.

6. The IMD of claim 1 , wherein the at least one of the processor or controller is configured to:
produce the plurality of sets of pairwise differences by determining pairwise differences between pairs of the R-R intervals within the window that are k intervals apart, for each of k=1 to M, where M is an integer that is at least 4, to thereby produce M indicators of a median R-R interval difference; and
determine the measure of the dominant repeated R-R interval pattern within the window by determining a minimum of the M indicators of the median R-R interval difference.

7. The IMD of claim 6 , wherein the M indicators of the median R-R interval difference that are determined comprise M median percent difference values each of which is determined using the equation:
Median Percent Difference for k =MEDIAN(100*| RR ( n )− RR ( n+k )|/ RR ( n )),

for intervals n=1:N and interval separations k=1:M,
where
RR(n) is a n th R-R interval within the window,
RR(n+k) is a (n+k) th R-R interval within the window,
|RR(n)−RR(n+k)| is the absolute value of RR(n)−RR(n+k), and
N is a total number of R-R intervals within the window.

8. A method for use by an implantable medical device (IMD) comprising at least one of a processor or controller, the method comprising the at least one of the processor or controller of the IMD:
(a) obtaining an ordered list of R-R intervals within a window leading up to a detection of a potential arrhythmia episode, wherein each of the R-R intervals has a respective duration;
(b) determining, based on the ordered list of R-R intervals within the window, pairwise differences between pairs of the R-R intervals that are various different intervals apart, to thereby produce a plurality of sets of pairwise differences;
(c) determining, based on the plurality of sets of pairwise differences, a measure of a dominant repeated R-R interval pattern;
(d) comparing the measure of the dominant repeated R-R interval pattern to a pattern threshold; and
(e) classifying the detection of the potential arrhythmia episode as a false positive, when the measure of the dominant repeated R-R interval pattern is below the pattern threshold, and in response thereto, preventing delivery of therapy to a patient's heart.

9. The method of claim 8 , wherein step (c) comprises:
for each set of pairwise intervals, of the plurality of sets of pairwise intervals, determining a median of the set or an indicator of the median, to thereby produce a plurality of medians or indicators of medians; and
determining the measure of the dominant repeated R-R interval pattern within the window by determining a minimum of the plurality of medians or indicators of the medians.

10. The method of claim 8 , wherein the potential arrhythmia episode comprises a potential atrial fibrillation (AF) episode.

11. The method of claim 8 , wherein:
the IMD that the method is used by comprises an implantable cardioverter defibrillator (ICD); and
the therapy comprises a shock to the patient's heart.

12. The method of claim 8 , wherein:
the IMD that the method is used by comprises a pacemaker.

13. The method of claim 8 , wherein:
step (b) comprises producing the plurality of sets of pairwise differences by determining pairwise differences between pairs of the R-R intervals within the window that are k intervals apart, for each of k=1 to M, where M is an integer that is at least 4, to thereby produce M indicators of a median R-R interval difference; and
step (c) comprises determining the measure of the dominant repeated R-R interval pattern within the window by determining a minimum of the M indicators of the median R-R interval difference.

14. The method of claim 13 , wherein the M indicators of the median R-R interval difference that are determined comprise M median percent difference values each of which is determined using the equation:
Median Percent Difference for k =MEDIAN(100*| RR ( n )− RR ( n+k )|/ RR ( n )),

for intervals n=1:N and interval separations k=1:M,
where
RR(n) is a n th R-R interval within the window,
RR(n+k) is a (n+k) th R-R interval within the window,
|RR(n)−RR(n+k)| is the absolute value of RR(n)−RR(n+k), and
N is a total number of R-R intervals within the window.

15. A method for use by an implantable medical device (IMD) comprising at least one of a processor or controller, the method comprising the at least one of the processor or controller of the IMD:
(a) obtaining an ordered list of R-R intervals within a window leading up to a detection of a potential arrhythmia episode, wherein each of the R-R intervals has a respective duration;
(b) for a value for k, selected from a range of values for k,
(b.1) determining a corresponding indicator of a median R-R interval difference between pairs of the R-R intervals within the window that are k intervals apart;
(b.2) comparing the indicator

Assignees

• Pacesetter Inc

Inventors

• Badie Nima
• Qu Fujian
• Gill Jong

Classifications

• A61B5/363 Primary

  Detecting tachycardia or bradycardia · CPC title

• A61N1/3956

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

• A61N1/3704

  Circuits specially adapted therefor, e.g. for sensitivity control · CPC title

• A61B5/361

  Detecting fibrillation · CPC title

• A61N1/3925

  Monitoring; Protecting · CPC title