Method and apparatus for generating a template for arrhythmia detection and electrogram morphology classification

• US 7,826,893 B2
• Filed: 06/04/2007
• Issued: 11/02/2010
• Est. Priority Date: 12/03/2003
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Gennaro, Chris J., Gillberg, Jeffrey M., Cao, Jian
• Primary Examiner(s): Schaetzle; Kennedy J
• Assistant Examiner(s): PATEL, NATASHA
• Application Number:
  US11/757,495
• Publication Number:
  US 20070276276A1
• Time in Patent Office: 1,247 Days
• Field of Search: 607/25, 607/14, 600/509, 600/513, 600515-519, 600/521
• US Class Current: 600/518
• CPC Class Codes: A61B 5/35 by template matching
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• 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 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

An implantable medical device and associated method for automatically generating morphology templates during fast cardiac rhythms, confirming a provisional template as a confirmed template, and using the confirmed template to classify subsequent detected arrhythmias. A provisional SVT template may be created during a fast ventricular rate and activated as a confirmed SVT template upon verification that the fast rate was due to an SVT. The confirmed SVT template may be used to discriminate SVT from VT/VF.

Claims

1. A method of discriminating with a medical device among individual ones of a plurality of cardiac complexes of a heart of a patient, comprising the steps of:

detecting a fast cardiac rate wherein the plurality of cardiac complexes are occurring at a rate corresponding to an arrhythmia detection interval;

sensing the plurality of cardiac complexes during the fast cardiac rate;

iteratively comparing each individual one of the plurality of cardiac complexes with each other one of the plurality of cardiac complexes to obtain a plurality of comparisons, each individual one of the plurality of comparisons corresponding to one of the plurality of cardiac complexes;

identifying one of the plurality of cardiac complexes as being representative of the plurality of cardiac complexes based, at least in part, on the plurality of comparisons; and

presenting the one of the plurality of cardiac complexes representative of the plurality of cardiac complexes to a user.

2. The method of claim 1, wherein the iteratively comparing step comprises:

transforming each of the plurality of cardiac complexes into a plurality of corresponding signal wavelet coefficients;

identifying higher amplitude ones of each of the plurality of corresponding signal wavelet coefficients;

wherein each of the plurality of comparisons are based, at least in part, on comparisons of the higher amplitude ones of each of the plurality of signal wavelet coefficients.

3. The method of claim 2, wherein transforming each of the plurality of cardiac complexes comprises transforming each of the plurality of cardiac complexes using a wavelet transform to obtain the plurality of corresponding signal wavelet coefficients.

4. The method of claim 1, further comprising:

identifying the fast cardiac rate as a supraventricular tachycardia;

identifying the one of the plurality of cardiac complexes representative of the plurality of cardiac complexes as a supraventricular tachycardia template based, at least in part, on the fast cardiac rate being a supraventricular tachycardia.

5. A method for monitoring heart rhythms comprised of a plurality of cardiac complexes with a medical device, comprising the steps of:

detecting a fast cardiac rate based, at least in part, on the plurality of cardiac complexes occurring at a rate corresponding to an arrhythmia detection interval;

sensing first individual ones of the plurality of cardiac complexes during the fast cardiac rate;

iteratively comparing each individual one of the first individual ones of the plurality of cardiac complexes with each other one of the first individual ones of the plurality of cardiac complexes to obtain a first plurality of comparisons, each individual one of the first plurality of comparisons corresponding to one of the first individual ones of the plurality of cardiac complexes;

identifying one of the first individual ones of the plurality of cardiac complexes as being representative of the first individual ones of the plurality of cardiac complexes based, at least in part, on the first plurality of comparisons;

presenting the one of the individual ones of the plurality of cardiac complexes representative of the first individual ones of the plurality of cardiac complexes to a user;

identifying the fast cardiac rate as a supraventricular tachycardia;

identifying the one of the first individual ones of the plurality of cardiac complexes representative of the first individual ones of the plurality of cardiac complexes as a supraventricular tachycardia template based, at least in part, on the fast cardiac rate being a supraventricular tachycardia;

then

sensing second individual ones of the plurality of cardiac complexes during an unknown rhythm;

transforming each of the second individual ones of the plurality of cardiac complexes into a plurality of corresponding signal wavelet coefficients;

identifying higher amplitude ones of each of the plurality of corresponding signal wavelet coefficients;

obtaining a second plurality of comparisons are based, at least in part, on comparisons of the higher amplitude ones of each of the corresponding plurality of signal wavelet coefficients; and

identifying the heart rhythm based, at least in part, on the second plurality of comparisons.

6. A method of discriminating with a medical device among individual ones of a plurality of cardiac complexes of a heart of a patient, comprising the steps of:

detecting a fast cardiac rate wherein the plurality of cardiac complexes are occurring at a rate corresponding to an arrhythmia detection interval;

sensing the plurality of cardiac complexes during the fast cardiac rate;

iteratively comparing each individual one of the plurality of cardiac complexes with each other one of the plurality of cardiac complexes to obtain a plurality of comparisons, each individual one of the plurality of comparisons corresponding to one of the plurality of cardiac complexes;

generating a template representative of the plurality of cardiac complexes based, at least in part, on the individual ones of the plurality of cardiac complexes and the plurality of comparisons; and

displaying the template to a user.

7. The method of claim 6 wherein each individual one of the plurality of comparisons is a morphological comparison of a corresponding one of the plurality of cardiac complexes with other ones of the plurality of cardiac complexes.

8. The method of claim 7 wherein the morphological comparison is a comparison of a wavelet transform of the corresponding one of the plurality of cardiac complexes with each other one of the plurality of cardiac complexes.

9. The method of claim 6 wherein each individual one of the plurality of comparisons is indicative of a degree to which the corresponding one of the plurality of cardiac complexes matches each other individual one of the plurality of cardiac complexes.

10. The method of claim 9 wherein the template is based on one of the plurality of cardiac complexes having a corresponding one of the plurality of comparisons having a highest degree to which the one of the plurality of cardiac complexes matches each other individual one of the plurality of cardiac complexes.

11. The method of claim 9 wherein the template is based on a predetermined number of the plurality of cardiac complexes having a corresponding one of the plurality of comparisons having a predetermined degree to which each of the predetermined number of the plurality of cardiac complexes matches each other individual one of the plurality of cardiac complexes.

12. The method of claim 6:

wherein a first one of the plurality of cardiac complexes matches a second one of the plurality of cardiac complexes if a morphological comparison of the first one of the plurality of cardiac complexes with the second one of the plurality of cardiac complexes is within a predetermined variance; and

wherein each individual one of the plurality of comparisons is indicative, at least in part, of a number of times the corresponding one of the plurality of cardiac complexes matches each other one of the plurality of cardiac complexes.

13. The method of claim 12 wherein the template is generated based on one of the plurality of cardiac complexes having a corresponding one of the plurality of comparisons indicating more of the matches than each other one of the plurality of comparisons.

14. The method of claim 12 wherein the template is generated based on each one of the plurality of cardiac complexes having a corresponding one of the plurality of comparisons indicating a number of the matches above a predetermined threshold.

15. The method of claim 14 wherein the template is generated based on an average of each one of the plurality of cardiac complexes having a corresponding one of the plurality of comparisons indicating a number of the matches above a predetermined threshold.

16. A system for discriminating among individual ones of a plurality of cardiac complexes of an electrical signal generated by a heart of a patient, comprising:

an electrode configured to sense the electrical signals of the heart;

a electronic componentry operatively coupled to the plurality of electrodes and configured to;

detect a fast cardiac rate wherein the plurality of cardiac complexes are occurring at a rate corresponding to an arrhythmia detection interval;

sense the plurality of cardiac complexes during the fast cardiac rate;

iteratively care each individual one of the plurality of cardiac complexes with each other one of the plurality of cardiac complexes to obtain a plurality of comparisons, each individual one of the plurality of comparisons corresponding to one of the plurality of cardiac complexes; and

generate a template representative of the plurality of cardiac complexes based, at least in part, on the individual ones of the plurality of cardiac complexes and the plurality of comparisons; and

a user output operatively coupled to the processor and configured to present the template to a user.

17. The system of claim 16 wherein each individual one of the plurality of comparisons is a morphological comparison of a corresponding one of the plurality of cardiac complexes with other ones of the plurality of cardiac complexes.

18. The system of claim 17 wherein the morphological comparison is a comparison of a wavelet transform of the corresponding one of the plurality of cardiac complexes with each other one of the plurality of cardiac complexes.

19. The system of claim 16 wherein each individual one of the plurality of comparisons is indicative of a degree to which the corresponding one of the plurality of cardiac complexes matches each other individual one of the plurality of cardiac complexes.

20. The system of claim 19 wherein the template is based on one of the plurality of cardiac complexes having a corresponding one of the plurality of comparisons having a highest degree to which the one of the plurality of cardiac complexes matches each other individual one of the plurality of cardiac complexes.

21. The system of claim 19 wherein the template is based on a predetermined number of the plurality of cardiac complexes having a corresponding one of the plurality of comparisons having a predetermined degree to which each of the predetermined number of the plurality of cardiac complexes matches each other individual one of the plurality of cardiac complexes.

22. The system of claim 16:

wherein a first one of the plurality of cardiac complexes matches a second one of the plurality of cardiac complexes if a morphological comparison of the first one of the plurality of cardiac complexes with the second one of the plurality of cardiac complexes is within a predetermined variance; and

wherein each individual one of the plurality of comparisons is indicative, at least in part, of a number of times the corresponding one of the plurality of cardiac complexes matches each other one of the plurality of cardiac complexes.

23. The system of claim 22 wherein the template is generated based on one of the plurality of cardiac complexes having a corresponding one of the plurality of comparisons indicating more of the matches than each other one of the plurality of comparisons.

24. The system of claim 22 wherein the template is generated based on each one of the plurality of cardiac complexes having a corresponding one of the plurality of comparisons indicating a number of the matches above a predetermined threshold.

25. The system of claim 24 wherein the template is generated based on an average of each one of the plurality of cardiac complexes having a corresponding one of the plurality of comparisons indicating a number of the matches above a predetermined threshold.