Discriminating polymorphic and monomorphic cardiac rhythms using template generation

• US 20070142736A1
• 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: Bocek, Joseph, Kim, Jaeho, Lin, Yayun, Zhang, Yi, Li, Dan, Cazares, Shelley, Ricci, Carlos
• Granted Patent: US 8,532,762 B2
• Time in Patent Office: Days
• US Class Current: 600/515
• CPC Class Codes: A61B 5/35 by template matching
• CPC Class Codes: A61B 5/361 Detecting fibrillation
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/366 Detecting abnormal QRS complex, e.g. widening
• 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: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: A61N 1/39622 Pacing therapy
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

Cardiac arrhythmias are classified based on the morphology of the arrhythmia episode beats. Templates are formed using morphological features of the cardiac beats of the episode. The arrhythmia episode is classified as a monomorphic tachyarrhythmia or polymorphic tachyarrhythmia based on the one or more templates. The arrhythmia episode may be classified based on a number templates formed from the arrhythmia episode. The templates are formed by determining a measure of similarity between morphological features of a cardiac beat to a template. The similarities can be determined based on a pairing rule that determines which beat morphologies are compared. Selection of therapy for treating the arrhythmia episode may depend on the historical success of a therapy at mitigating previous arrhythmias of the same type as the arrhythmia episode.

Claims

1. A method of arrhythmia discrimination for implementation by an implantable cardiac rhythm management device, comprising:

detecting cardiac beats associated with an arrhythmia episode;

forming one or more templates using morphological features of the cardiac beats of the arrhythmia episode; and

determining if the arrhythmia episode is monomorphic tachyarrhythmia or polymorphic tachyarrhythmia based on similarity of the one or more templates.

2. The method of claim 1, wherein determining if the arrhythmia episode is monomorphic tachyarrhythmia or polymorphic tachyarrhythmia comprises determining based on a number of the one or more templates formed using the cardiac beats of the arrhythmia episode.

3. The method of claim 1, wherein forming the one or more templates comprises:

determining a measure of similarity between morphological features of a cardiac beat to a template; and

forming an additional template using the cardiac beat based on the measure of similarity.

4. The method of claim 1, wherein forming the one or more templates comprises:

determining a measure of similarity between morphological features of a cardiac beat to a template; and

modifying a previously formed template using the cardiac beat based on the measure of similarity.

5. The method of claim 1, wherein the measure of similarity comprises a correlation coefficient.

6. The method of claim 1, wherein determining if the arrhythmia episode is monomorphic tachyarrhythmia or polymorphic tachyarrhythmia comprises determining the similarity the one or more templates by comparing the one or more templates using a pairing rule.

7. The method of claim 6, wherein the pairing rule comprises comparing one or more pairs of adjacent cardiac beats.

8. The method of claim 6, wherein the pairing rule comprises comparing a most recent template to each prior template.

9. The method of claim 6, wherein the pairing rule comprises comparing of all possible template combinations.

10. The method of claim 1, wherein determining if the arrhythmia episode is monomorphic tachyarrhythmia or polymorphic tachyarrhythmia based on the similarity of the one or more templates comprises determining a morphology regularity measure of the one or more templates.

11. The method of claim 1, wherein at least one of forming the one or more templates and determining if the arrhythmia episode is monomorphic tachyarrhythmia or polymorphic tachyarrhythmia is performed during the arrhythmia episode.

12. The method of claim 1, further comprising:

storing a particular template of the one or more templates, the particular template representative of the arrhythmia episode; and

classifying a subsequent monomorphic tachyarrhythmia episode according to monomorphic arrhythmia type using the particular template.

13. The method of claim 1, further comprising confirming a determination of supraventricular tachyarrhythmia if the arrhythmia episode is determined to be monomorphic tachyarrhythmia.

14. The method of claim 1, further comprising:

classifying the arrhythmia episode according to monomorphic arrhythmia type if the arrhythmia episode is determined to be monomorphic tachyarrhythmia; and

selecting a therapy based on at least one of the determination that the arrhythmia episode is monomorphic tachyarrhythmia or polymorphic tachyarrhythmia and the classification of the arrhythmia episode.

15. The method of claim 1, further comprising selecting a therapy to treat the arrhythmia episode based on a history of satisfactory treatment.

16. An implantable medical device, comprising:

sensor circuitry comprising electrodes for electrically coupling to a heart, the sensor circuitry configured to detect cardiac beats associated with an cardiac arrhythmia episode;

a template generator coupled to the sensor circuitry and configured to form one or more templates using the detected cardiac beats; and

an arrhythmia processor coupled to the template generator, the arrhythmia processor configured to determine if the arrhythmia episode is monomorphic tachyarrhythmia or polymorphic tachyarrhythmia based on similarity of the one or more templates.

17. The device of claim 16, wherein the similarity of the one or more templates is determined by calculating a correlation coefficient comparing a template and a cardiac beat.

18. The device of claim 16, wherein the arrhythmia processor is configured to determine if the arrhythmia episode is monomorphic tachyarrhythmia or polymorphic tachyarrhythmia based on a number of the one or more templates formed from the arrhythmia episode beats.

19. The device of claim 16, wherein the template is configured to modify a template using cardiac beats of the arrhythmia episode that are similar to the template.

20. The device of claim 16, wherein the arrhythmia processor is configured to determine the similarity of the one or more templates based on a pairing rule.

21. The device of claim 16, further comprising a memory for storing particular templates of the one or more templates, wherein the arrhythmia processor is configured to classify subsequently detected monomorphic arrhythmia episodes according to monomorphic arrhythmia type using the one or more of the particular templates.

22. The device of claim 21, further comprising:

a control system configured to select an electrical stimulation therapy to treat a subsequently detected monomorphic arrhythmia episode based on the classification according to monomorphic arrhythmia type; and

therapy circuitry configured to deliver the selected therapy.

23. The device of claim 16, further comprising:

a control system configured to select an electrical stimulation therapy based on the determination of monomorphic tachyarrhythmia or polymorphic tachyarrhythmia; and

therapy circuitry configured to deliver the selected therapy.

24. A system for arrhythmia discrimination, comprising:

means for detecting cardiac beats associated with an arrhythmia episode;

means for forming one or more templates using morphological features of the cardiac beats of the arrhythmia episode; and

means for determining if the arrhythmia episode is monomorphic tachyarrhythmia or polymorphic tachyarrhythmia based on similarity of the one or more templates.

25. The system of claim 24, further comprising means for determining if the arrhythmia episode is monomorphic tachyarrhythmia or polymorphic tachyarrhythmia based on a number of the one or more templates formed from the arrhythmia episode.

26. The system of claim 24, further comprising means for determining the similarity of the one or more templates based on a pairing rule.

27. The system of claim 24, further comprising means for classifying the arrhythmia episode according to monomorphic arrhythmia type if the arrhythmia episode is determined to be monomorphic tachyarrhythmia.

28. The system of claim 27, further comprising means for selecting a therapy based on at least one of the determination that the arrhythmia episode is monomorphic tachyarrhythmia or polymorphic tachyarrhythmia and the monomorphic arrhythmia type of the arrhythmia episode.