Arrhythmia discrimination based on determination of rate dependency

• US 20070142737A1
• Filed: 12/20/2005
• Published: 06/21/2007
• Est. Priority Date: 12/20/2005
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Kim, Jaeho, Lin, Yayun, Cazares, Shelley, Ricci, Carlos
• Granted Patent: US 7,653,431 B2
• Time in Patent Office: Days
• US Class Current: 600/515
• CPC Class Codes: A61B 5/35 by template matching
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

Cardiac systems and methods provide for discriminating between supraventricular tachyarrhythmia and ventricular tachyarrhythmia based on a determination that the patient'"'"'s supraventricular rhythm exhibits rate dependency. One approach involves determining if a patient'"'"'s supraventricular rhythm exhibits rate dependent morphology. If the patient'"'"'s supraventricular rhythm is determined to exhibit rate dependent morphology, an implantable device classifies a detected tachyarrhythmia episode based on one or more templates selected from a plurality of rate-indexed templates stored in the device. Determining if the supraventricular rhythm exhibits rate dependent morphology may also include determining one or more rates at which the rate dependent morphology occurs.

Claims

1. A method, comprising:

determining if a patient'"'"'s supraventricular rhythm exhibits rate dependent morphology; and

classifying a tachyarrhythmia episode based on one or more templates selected from a plurality of rate-indexed templates if the supraventricular rhythm exhibits rate-dependent morphology.

2. The method of claim 1, wherein determining if the supraventricular rhythm exhibits rate dependent morphology comprises:

creating supraventricular tachyarrhythmia by atrial pacing at multiple pacing rates;

sensing cardiac waveforms during the created supraventricular tachyarrhythmia; and

determining if the supraventricular rhythm exhibits rate dependent morphology based on morphologies of the cardiac waveforms.

3. The method of claim 2, wherein the atrial pacing is delivered at progressively higher rates.

4. The method of claim 2, wherein the atrial pacing is delivered in accordance with an automated atrial pacing pattern.

5. The method of claim 1, wherein determining if the supraventricular rhythm exhibits rate dependent morphology comprises:

creating supraventricular tachyarrhythmia by altering patient activity under controlled conditions; and

sensing cardiac waveforms during the created supraventricular tachyarrhythmia; and

determining if the supraventricular rhythm exhibits rate dependent morphology based on the morphologies of the cardiac waveforms.

6. The method of claim 1, wherein determining if the supraventricular rhythm exhibits rate dependent morphology comprises:

creating supraventricular tachyarrhythmia by administration of drugs to the patient;

sensing cardiac waveforms during the created supraventricular tachyarrhythmia; and

determining if the supraventricular rhythm exhibits rate dependent morphology based on morphologies of the cardiac waveforms.

7. The method of claim 1, wherein determining if the supraventricular rhythm exhibits rate dependent morphology comprises determining one or more rates at which a change in morphology occurs.

8. The method of claim 1, further comprising forming or updating the plurality of rate-indexed templates using cardiac waveforms sensed during created episodes of supraventricular tachyarrhythmia.

9. The method of claim 1, further comprising:

detecting spontaneous episodes of supraventricular tachyarrhythmia; and

forming or updating the plurality of rate-indexed templates based on morphologies of cardiac waveforms sensed during the spontaneous episodes of supraventricular tachyarrhythmia.

10. The method of claim 9, further comprising confirming the spontaneous episodes of supraventricular tachyarrhythmia using at least one of episode morphology, AV delay stability, and correspondence between atrial and ventricular rates.

11. The method of claim 9, further comprising confirming the spontaneous episodes of supraventricular tachyarrhythmia using a subcutaneously generated electrocardiogram signal.

12. The method of claim 1, wherein classifying the tachyarrhythmia episode comprises:

estimating a rate of the tachyarrhythmia episode; and

selecting the one or more templates respectively associated with one or more rates closest to or below the estimated tachyarrhythmia episode rate.

13. The method of claim 1, wherein classifying the tachyarrhythmia episode comprises:

forming a template estimate based on interpolation between at least two of the templates; and

classifying the tachyarrhythmia episode using the template estimate.

14. The method of claim 1, wherein classifying the tachyarrhythmia episode comprises:

selecting, based on rate, an initial template from the plurality of rate-indexed templates; and

searching for the one or more templates based on the initial template and on morphological similarities between the one or more templates and cardiac waveforms sensed during the tachyarrhythmia episode.

15. A medical system, comprising:

a lead system comprising cardiac electrodes configured to sense cardiac waveforms;

a template generator configured to form a plurality of rate-indexed templates characterizing cardiac waveforms sensed during supraventricular tachyarrhythmia; and

an arrhythmia classification processor configured to classify cardiac rhythms using one or more templates selected from the plurality of rate-indexed templates if the patient'"'"'s supraventricular rhythm exhibits rate dependent morphology.

16. The medical system of claim 15, further comprising:

a cardiac pacing circuit configured to create the supraventricular tachyarrhythmia through atrial pacing; and

a control system configured to determine if the supraventricular rhythm exhibits rate dependent morphology based on cardiac waveforms sensed during the created supraventricular tachyarrhythmia and to form the plurality of rate-indexed templates using the cardiac waveforms sensed during the supraventricular tachyarrhythmia.

17. The medical system of claim 16, wherein the atrial pacing is delivered at progressively higher rates.

18. The medical system of claim 16, wherein the atrial pacing is delivered in accordance with an automated atrial pacing pattern.

19. The medical system of claim 15, wherein the template generator is configured to form or modify the plurality of rate-indexed templates using cardiac waveforms sensed during spontaneous supraventricular tachyarrhythmia.

20. The medical system of claim 15, wherein at least one of the template generator and the arrhythmia classification processor include a patient-external component.

21. The medical system of claim 15, wherein at least one of the template generator and the arrhythmia classification processor include an implantable component.

22. The medical system of claim 15, wherein one or both of the template generator and the arrhythmia classification processor are disposed within a housing of an implantable cardiac rhythm management device.

23. A medical system, comprising:

means for forming rate indexed templates characterizing cardiac waveforms sensed during created supraventricular tachyarrhythmia; and

means for classifying the cardiac rhythms using selected ones of the rate indexed templates if the cardiac waveforms exhibit rate dependent morphology.

24. The medical system of claim 23, further comprising means for creating the supraventricular tachyarrhythmia through atrial pacing.

25. The medical system of claim 23, further comprising means for determining if the cardiac waveforms exhibit rate dependent morphology.