Rhythm discrimination enhancement—AV drive

• US 8,403,830 B2
• Filed: 08/02/2011
• Issued: 03/26/2013
• Est. Priority Date: 08/06/2010
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Mahajan, Deepa, Dong, Yanting, Perschbacher, David L.
• Primary Examiner(s): MANUEL, GEORGE C
• Application Number:
  US13/196,491
• Publication Number:
  US 20120035491A1
• Time in Patent Office: 602 Days
• Field of Search: 600/118, 600/119
• US Class Current: 600/118
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/3624 occurring in the atrium, i.e. atrial tachycardia
• CPC Class Codes: A61N 1/3704 Circuits specially adapted therefor, e.g. for sensitivity control
• CPC Class Codes: A61N 1/3962 in combination with another heart therapy
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

An apparatus comprises an implantable cardiac signal sensing circuit and a controller circuit. The implantable cardiac signal sensing circuit provides a sensed depolarization signal from a ventricle and a sensed depolarization signal from an atrium. The controller circuit includes a one-to-one detector circuit and a tachyarrhythmia discrimination circuit. The one-to-one detector circuit measures cardiac depolarization intervals of the atrium and the ventricle and determines whether a relationship of atrial depolarizations to ventricular depolarizations is substantially one-to-one. The tachyarrhythmia discrimination circuit increments a counter when detecting a shortening or prolonging of a V-V interval that immediately precedes the same shortening or prolonging of an A-A interval, classifies the episode as VT according to the counter, and provides the classification of the tachyarrhythmia episode to a user or process.

Claims

1. An apparatus comprising:

an implantable cardiac signal sensing circuit, configured to provide a sensed depolarization signal from a ventricle and a sensed depolarization signal from an atrium; and

a controller circuit communicatively coupled to the implantable cardiac signal sensing circuit, wherein the controller circuit includes;

a one-to-one detector circuit configured to;

measure cardiac depolarization intervals of the atrium and the ventricle; and

determine whether a relationship of atrial (A-A) depolarizations to ventricular (V-V) depolarizations is substantially one-to-one;

a first counter circuit and a second counter circuit; and

a tachyarrhythmia discrimination circuit configured to;

detect an episode of tachyarrhythmia while the relationship atrial depolarizations to ventricular depolarizations is substantially one-to-one;

increment the first counter when detecting one of a shortening or prolonging of a V-V interval that is immediately preceded by the same one of a detected shortening or prolonging of an A-A interval during the episode;

increment the second counter when detecting one of a shortening or prolonging of an A-A interval during the episode that is immediately preceded by the same one of a shortening or prolonging of a V-V interval and an interval from a ventricular depolarization to an atrial depolarization (V-A) is greater than a specified threshold V-A interval value;

classify the episode as VT when the count of the second counter exceeds the count of the first counter by a specified threshold count; and

provide the classification of the tachyarrhythmia episode to a user or process.

2. The apparatus of claim 1, wherein the tachyarrhythmia discrimination circuit configured to classify the episode as SVT when a count of the first counter exceeds a count of the second counter by the specified threshold count.

3. The apparatus of claim 1,

wherein the one-to-one detector circuit is configured to:

monitor cardiac depolarization intervals as they occur in real time;

continue the monitoring while the relationship is determined to be substantially one-to-one and a difference between the count of the first counter and the count of the second counter is less than the specified threshold count; and

wherein the controller circuit is configured to initiate storage of at least one of an electrogram and a marker when at least one of the relationship is determined to be different than substantially one-to-one or the relationship is determined to be substantially one-to-one and the difference between the count of the first counter and the count of the second counter exceeds the specified threshold count.

4. The apparatus of claim 1, wherein the one-to-one detector circuit is configured to deem that the relationship of atrial depolarizations to ventricular depolarizations is substantially one-to-one when the difference between a number of atrial depolarizations and a number of ventricular depolarizations during the episode is less than a specified threshold depolarization difference value.

5. The apparatus of claim 4, wherein the cardiac signal sensing circuit is configured to sense a depolarization during a device-specified refractory period, and wherein the one-to-one detector circuit is configured to include the depolarization in the one-to-one determination unless determining that the sensed depolarization is a far-field sensed event.

6. The apparatus of claim 4, wherein the one-to-one detector circuit is configured to deem that the relationship of depolarizations is substantially one-to-one during the episode when:

the number of atrial depolarizations is more than a number of detected ventricular depolarizations but is less than first specified threshold depolarization difference value; and

the number of ventricular depolarizations is more than a number of detected atrial depolarizations but is less than a second specified threshold depolarization difference value.

7. The apparatus of claim 1, wherein the one-to-one detector circuit is configured to deem that the relationship of atrial depolarizations to ventricular depolarizations is substantially one-to-one when the detected ventricular rate differs from the detected atrial rate by less than a specified rate difference.

8. The apparatus of claim 1, wherein the tachyarrhythmia discrimination circuit cancels one-to-one monitoring when detecting a depolarization rate or depolarization interval that satisfies a ventricular fibrillation (VF) detection rate threshold or VF detection interval threshold.

9. The apparatus of claim 1, wherein the tachyarrhythmia discrimination circuit is configured to detect a tachyarrhythmia episode when a determined depolarization rate or interval satisfies a lowest tachyarrhythmia detection threshold rate or interval.

10. The apparatus of claim 1, including a therapy circuit communicatively coupled to the controller circuit and configured to provide at least one of cardioversion shock therapy, defibrillation shock therapy, and anti-tachyarrhythmia pacing (ATP) therapy, and

wherein the controller circuit is configured to delay delivery of anti-tachyarrhythmia therapy when A-A depolarization interval durations and V-V interval durations remain unchanged during the episode.

11. A method comprising:

monitoring cardiac depolarization intervals in an atrium and in a ventricle of a heart of a subject using an implantable medical device (IMD);

detecting an episode of tachyarrhythmia using the IMD;

determining that a relationship of atrial (A-A) depolarizations to ventricular (V-V) depolarizations is substantially one-to-one during the episode;

incrementing a first counter when detecting one of a shortening or prolonging of an A-A interval that immediately precedes the same one of a shortening or prolonging of the V-V interval during the episode;

incrementing a second counter when detecting one of a shortening or prolonging of a V-V interval that immediately precedes the same one of a shortening or prolonging of the A-A interval during the episode and an interval from a ventricular depolarization to an atrial depolarization (V-A) is greater than a specified threshold V-A interval value;

classifying the episode as ventricular tachycardia (VT) when the count of the second counter exceeds the count of the first counter by a specified threshold count; and

providing the classification of the tachyarrhythmia episode to a user or process.

12. The method of claim 11, including:

classifying the episode as supra-ventricular tachycardia (SVT) when a count of the first counter exceeds a count of the second counter by a specified threshold count.

13. The method of claim 11, including:

monitoring cardiac depolarization intervals as they occur in real time;

continuing the monitoring while the relationship is determined to be substantially one-to-one and a difference between counts of the first counter circuit and the second counter circuit is less than the specified threshold count; and

initiating storage of at least one of an electrogram and a marker when at least one of the relationships is determined to be different than substantially one-to-one or the relationship is determined to be substantially one-to-one and the difference between the count of the first counter and the count of the second counter satisfies the specified threshold count.

14. The method of claim 11, wherein determining a relationship of atrial depolarizations to ventricular depolarizations includes deeming that the relationship is substantially one-to-one when the difference between a number of atrial depolarizations and a number of ventricular depolarizations during the episode is less than a specified threshold depolarization difference value.

15. The method of claim 14, including:

sensing a depolarization during a device refractory period; and

including the depolarization in the one-to-one determination unless determining that the sensed depolarization is a far-field sensed event.

16. The method of claim 14, wherein deeming that the relationship is substantially one-to-one includes:

deeming that the relationship is substantially one-to-one when the number of atrial depolarizations is more than the number of ventricular depolarizations but is less than a first specified threshold depolarization difference value; and

deeming that the relationship is substantially one-to-one when the number of ventricular depolarizations is more than the number of atrial depolarizations but is less than a second specified threshold depolarization difference value.

17. The method of claim 11, wherein determining a relationship of atrial depolarizations to ventricular depolarizations includes deeming that the relationship is substantially one-to-one when the detected ventricular rate differs from the detected atrial rate by less than a specified rate difference.

18. The method of claim 11, including:

calculating a net change over N depolarization intervals, where N is an integer; and

declaring a change in a depolarization interval when the calculated total net interval change exceeds a specified threshold value.

19. The method of claim 11, wherein detecting an episode of tachyarrhythmia includes detecting a tachyarrhythmia episode when a determined depolarization rate or interval satisfies a lowest tachyarrhythmia detection threshold rate or interval.

20. The method of claim 11, including delaying anti-tachyarrhythmia therapy when A-A depolarization interval durations and V-V interval durations remain unchanged during the episode.