Blending cardiac rhythm detection processes

• US 8,145,301 B2
• Filed: 09/30/2010
• Issued: 03/27/2012
• Est. Priority Date: 03/24/2005
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Lovett, Eric G., Kim, Jaeho, Bocek, Joseph M., Thompson, Julie A.
• Primary Examiner(s): Layno, Carl H.
• Assistant Examiner(s): Morales, Jon-Eric C.
• Application Number:
  US12/895,151
• Publication Number:
  US 20110021934A1
• Time in Patent Office: 544 Days
• Field of Search: 607/5, 600/515, 600/518, 600/508
• US Class Current: 607/5
• CPC Class Codes: A61B 5/35 by template matching
• 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 1/3925 Monitoring; Protecting
• CPC Class Codes: A61N 1/395 for treating atrial fibrillation
• 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

Systems and methods are described for classifying a cardiac rhythm. A cardiac rhythm is classified using a classification process that includes a plurality of cardiac rhythm discriminators. Each rhythm discriminator provides an independent classification of the cardiac rhythm. The classification process is modified if the modification is likely to produce enhanced classification results. The rhythm is reclassified using the modified classification process.

Claims

1. A method for classifying a tachyarrhythmia in a heart, the method comprising:

sensing, at a patient device, one or more sequences of atrial and ventricular contractions associated with the tachyarrhythmia;

selecting, at the patient device, one or more patterns that represent an onset pattern, the patterns including respective sequences of atrial and ventricular contractions; and

obtaining, at the patient device, a first classification of the tachyarrhythmia based on whether a match exists between the one or more sequences of atrial and ventricular contractions and the one or more patterns.

2. The method in claim 1, comprising:

detecting whether the tachyarrhythmia is sudden onset;

determining whether an atrial rate is approximately equal to a ventricular rate; and

if the tachyarrhythmia is sudden onset and the atrial rate is approximately equal to the ventricular rate, then classifying the tachyarrhythmia using whether the match exists.

3. The method of claim 1, wherein the obtaining the first classification comprises:

identifying a sequence of atrial and ventricular contractions associated with the tachyarrhythmia; and

classifying the sequence as more likely indicative of ventricular tachyarrhythmia if two or more ventricular contractions occur between consecutive atrial contractions within the sequence.

4. The method of claim 1, wherein the obtaining the first classification comprises:

identifying a sequence of atrial and ventricular contractions associated with the tachyarrhythmia; and

classifying the sequence as more likely indicative of supraventricular tachyarrhythmia if two or more atrial contractions occur between consecutive ventricular contractions within the sequence.

5. The method of claim 1, wherein the obtaining the first classification comprises:

identifying a sequence of atrial and ventricular contractions associated with the tachyarrhythmia; and

classifying the sequence as more likely indicative of ventricular tachyarrhythmia if two or more consecutive ventricular contractions occur between consecutive atrial contractions without having two or more consecutive atrial contractions occur between consecutive ventricular contractions within the sequence.

6. The method of claim 1, comprising:

establishing a matching threshold value using a result of the first classification; and

performing a comparison using the established matching threshold value to obtain a second classification of the tachyarrhythmia.

7. The method of claim 6, wherein the comparison is a morphology analysis.

8. The method of claim 6, comprising:

determining whether a therapy is necessary;

choosing a therapy using the second classification if a therapy is deemed necessary; and

delivering the therapy.

9. The method of claim 6, wherein the establishing the matching threshold comprises at least one of:

raising or maintaining the matching threshold if the first classification is ventricular tachycardia; and

lowering or maintaining the matching threshold if the first classification is supraventricular tachycardia.

10. A tachyarrhythmia detection and classification system, comprising:

a sensing circuit, adapted to sense at least one cardiac signal; and

a control system, coupled to the sensing circuit, the control system including;

an arrhythmia classification processor adapted to detect a tachyarrhythmia based on a heart rate obtained from the at least one cardiac signal; and

an rhythm discriminator adapted to obtain a first classification of a tachyarrhythmia as either ventricular tachycardia (VT) or supraventricular tachycardia (SVT) based on whether one or more patterns exists in a sequence of atrial and ventricular depolarizations detected by the arrhythmia detection module, the one or more patterns representing an onset pattern, and the patterns including respective sequences of atrial and ventricular contractions.

11. The system of claim 10, wherein the rhythm discriminator is adapted to detect a sudden onset of a tachyarrhythmia.

12. The system of claim 10, wherein the rhythm discriminator is adapted to detect when the atrial rate is substantially equal to a ventricular rate.

13. The system of claim 10, wherein the rhythm discriminator module is adapted to:

access a memory for representing a sequence of atrial or ventricular contractions;

access a pattern of two or more ventricular contractions occurring between consecutive atrial contractions; and

classify the sequence as more likely indicative of ventricular tachyarrhythmia if the pattern is found in the sequence.

14. The system of claim 10, wherein the rhythm discriminator module is adapted to:

access a memory for representing a sequence of atrial or ventricular contractions;

access a pattern of two or more atrial contractions occurring between consecutive ventricular contractions; and

classify the sequence as more likely indicative of supraventricular tachyarrhythmia if the pattern is found in the sequence.

15. The system of claim 10, wherein the rhythm discriminator module is adapted to:

access a matching threshold value that is established based on the first classification; and

compare a morphology of one or more beats under examination to a template morphology using the established matching threshold value to obtain a second classification of the tachyarrhythmia.

16. The system of claim 15, comprising a therapy control, coupled to the control system, and adapted to provide one or more therapies based on a result from the arrhythmia discriminator module.

17. A non-transitory machine-readable storage medium comprising instructions, which when executed by a machine, cause the machine to:

sense one or more sequences of atrial and ventricular contractions associated with the tachyarrhythmia;

select one or more patterns that represent an onset pattern, the patterns including respective sequences of atrial and ventricular contractions; and

obtain a first classification of the tachyarrhythmia based on whether a match exists between the one or more sequences of atrial and ventricular contractions and the one or more patterns.

18. The non-transitory machine-readable storage medium of claim 17, comprising instructions, which when executed by the machine, cause the machine to:

identify a sequence of atrial and ventricular contractions associated with the tachyarrhythmia; and

classify the sequence as more likely indicative of ventricular tachyarrhythmia if two or more ventricular contractions occur between consecutive atrial contractions within the sequence.

19. The non-transitory machine-readable storage medium of claim 17, comprising instructions, which when executed by the machine, cause the machine to:

identifying a sequence of atrial and ventricular contractions associated with the tachyarrhythmia; and

classifying the sequence as more likely indicative of supraventricular tachyarrhythmia if two or more atrial contractions occur between consecutive ventricular contractions within the sequence.

20. The non-transitory machine-readable storage medium of claim 17, wherein the one or more patterns define respective sequences of individual atrial and ventricular contractions.

21. The non-transitory machine-readable storage medium of claim 17, wherein the one or more patterns define individual contraction ordering of respective sequences of one or more individual atrial contractions interspersed together with one or more individual ventricular contractions.

22. The non-transitory machine-readable storage medium of claim 17, wherein the one or more patterns are pre-defined.

23. The non-transitory machine-readable storage medium of claim 17, wherein the one or more patterns represent an onset pattern and are selected from the group of:

A1-V1-V2-A2, A1-V1-A2-V2, and A1-A2-V1-A3-V2; and

wherein the instructions to obtain the first classification include instructions to determine at least one pattern selected from the group appears in the one or more sequences of atrial and ventricular contractions.