Blending cardiac rhythm detection processes

• US 7,818,056 B2
• Filed: 03/24/2005
• Issued: 10/19/2010
• 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: Kim, Jaeho, Bocek, Joseph M., Lovett, Eric G., Thompson, Julie A.
• Primary Examiner(s): Layno; Carl H.
• Assistant Examiner(s): MORALES, JON ERIC C
• Application Number:
  US11/089,185
• Publication Number:
  US 20060217621A1
• Time in Patent Office: 2,035 Days
• Field of Search: 600/515
• 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 cardiac rhythm using an implantable medical device, comprising:

sensing a cardiac rhythm using an implantable medical device;

classifying the cardiac rhythm using a classification process comprising a plurality of cardiac rhythm discriminators including a morphology-based rhythm discriminator that utilizes a correlation threshold parameter, each rhythm discriminator providing an independent classification of the cardiac rhythm;

determining if modifying the classification process is likely to enhance classification;

modifying the classification process if the classification is likely to be enhanced, the modifying including changing the correlation threshold parameter of the morphology-based rhythm discriminator, wherein modifying the classification process comprises modifying a first parameter of a first rhythm discriminator based on a second parameter of a second rhythm discriminator;

reclassifying the cardiac rhythm using the modified classification process; and

providing an output based on the reclassification of the cardiac rhythm.

2. The method of claim 1, further comprising classifying the cardiac rhythm based on results of the plurality of rhythm discriminators if modifying the classification process is not likely to enhance classification.

3. The method of claim 1, wherein determining if the cardiac rhythm classification is likely to be enhanced comprises determining if two or more of the plurality of rhythm discriminators produce conflicting results.

4. The method of claim 1, wherein determining if the cardiac rhythm classification is likely to be enhanced comprises determining if at least one of the plurality of rhythm discriminators produces indeterminate results.

5. The method of claim 1, wherein classifying the cardiac rhythm using the morphology-based rhythm discriminator comprises comparing a morphology of one or more cardiac beats of the cardiac rhythm to a morphology template.

6. The method of claim 1, wherein classifying the cardiac rhythm comprises classifying the cardiac rhythm using at least one interval-based rhythm discriminator.

7. The method of claim 6, wherein classifying the cardiac rhythm using the at least one interval-based rhythm discriminator comprises classifying the cardiac rhythm based on a relationship between an atrial rate and a ventricular rate of the cardiac rhythm.

8. The method of claim 1, wherein modifying the classification process comprises modifying one or more parameters of at least one of the plurality of rhythm discriminators.

9. The method of claim 1, wherein:

modifying the classification process comprises acquiring sensor information associated with the patient'"'"'s metabolic requirements; and

reclassifying the cardiac rhythm comprises reclassifying the cardiac rhythm using the acquired sensor information.

10. The method of claim 1, wherein the classifying, determining, modifying, reclassifying, and providing are carried out using the implantable medical device.

11. The method of claim 1, wherein the output comprises a therapy control signal for delivering or withholding therapy based on the reclassification of the cardiac rhythm.

12. A cardiac device, comprising:

a sensing circuit configured to implantably sense cardiac signals associated with a cardiac rhythm;

a plurality of independent rhythm discriminators configured to classify the cardiac rhythm, the plurality of discriminators including a morphology-based rhythm discriminator that utilizes a correlation threshold parameter; and

a classification processor coupled to the independent rhythm discriminators, the classification processor configured to implement a classification process to classify the cardiac rhythm, the classification process based on results of the independent rhythm discriminators, the classification processor further configured to determine if modification of the classification process is likely to enhance rhythm classification and to modify, if the rhythm classification is likely to be enhanced, the classification process by changing the correlation threshold parameter of the morphology-based rhythm discriminator, the classification processor further configured to reclassify the cardiac rhythm using the modified classification process, wherein the classification processor is configured to determine that the classification is likely to be enhanced if results of at least one of the plurality of independent rhythm discriminators is indeterminate.

13. The cardiac device of claim 12, wherein the classification processor is configured to determine that the classification is likely to be enhanced if results of at least two of the plurality of independent rhythm discriminators conflict.

14. The cardiac device of claim 12, wherein at least one of the plurality of independent rhythm discriminators comprises an interval-based discriminator.

15. The cardiac device of claim 12, wherein at least one of the plurality of independent rhythm discriminators is configured to classify the cardiac rhythm based on a relationship between an atrial rate and a ventricular rate of the cardiac rhythm.

16. The cardiac device of claim 12, wherein the classification processor is configured to modify a parameter of at least one of the plurality of rhythm discriminators.

17. The cardiac device of claim 12, further comprising a metabolic sensor configured to determine information associated with a patient'"'"'s metabolic need, wherein the classification processor is configured to use the metabolic information to modify the classification process.

18. The cardiac device of claim 12, wherein the sensing circuit, the plurality of independent rhythm discriminators, and the classification processor are disposed in an implantable housing.

19. The cardiac device of claim 12, wherein the classification processor is configured to modify a first parameter of a first rhythm discriminator based on a second parameter of a second rhythm discriminator.

20. The cardiac device of claim 12, further comprising a therapy delivery unit coupled to the classification processor, the therapy delivery unit configured to deliver or withhold therapy based on the reclassification of the cardiac rhythm.

21. A device for classifying a cardiac rhythm, comprising:

means for sensing a cardiac rhythm using an implantable medical device;

means for classifying the cardiac rhythm using a classification process comprising a plurality of cardiac rhythm discriminators including a morphology-based rhythm discriminator that utilizes a correlation threshold parameter, each rhythm discriminator providing an independent classification of the cardiac rhythm;

means for determining if modifying the classification process is likely to enhance classification by determining if at least one of the plurality of rhythm discriminators produces indeterminate results;

means for modifying the classification process if the classification is likely to be enhanced, the modifying including changing the correlation threshold parameter of the morphology-based rhythm discriminator;

means for reclassifying the cardiac rhythm using the modified classification process; and

means for providing an output based on the reclassification of the cardiac rhythm.

22. The device of claim 21, wherein the means for determining determines if two of more of the plurality of rhythm discriminators produce conflicting results.

23. The device of claim 21, wherein the output comprises a therapy control signal for delivering or withholding therapy based on the reclassification of the cardiac rhythm.

24. A method for classifying a cardiac rhythm using an implantable medical device, comprising:

sensing a cardiac rhythm using an implantable medical device;

classifying the cardiac rhythm using a classification process comprising a plurality of cardiac rhythm discriminators including a morphology-based rhythm discriminator that utilizes a correlation threshold parameter, each rhythm discriminator providing an independent classification of the cardiac rhythm;

determining if modifying the classification process is likely to enhance classification by determining if at least one of the plurality of rhythm discriminators produces indeterminate results;

modifying the classification process if the classification is likely to be enhanced, the modifying including changing the correlation threshold parameter of the morphology-based rhythm discriminator;

reclassifying the cardiac rhythm using the modified classification process; and

providing an output based on the reclassification of the cardiac rhythm, wherein classifying, determining, modifying, and reclassifying are performed at least in part by circuitry of the implantable medical device.

25. A method for classifying a cardiac rhythm using an implantable medical device, comprising:

sensing a cardiac rhythm using an implantable medical device;

classifying the cardiac rhythm using a classification process comprising a plurality of cardiac rhythm discriminators including a morphology-based rhythm discriminator that utilizes a correlation threshold parameter, each rhythm discriminator providing an independent classification of the cardiac rhythm;

determining if modifying the classification process is likely to enhance classification;

acquiring sensor information associated with metabolic requirements;

modifying the classification process if the classification is likely to be enhanced, the modifying including and changing the correlation threshold parameter of the morphology-based rhythm discriminator;

reclassifying the cardiac rhythm using the acquired sensor information and the modified classification process; and

providing an output based on the reclassification of the cardiac rhythm, wherein classifying, determining, modifying, and reclassifying are performed at least in part by circuitry of the implantable medical device.

26. A cardiac device, comprising:

a sensing circuit configured to implantably sense cardiac signals associated with a cardiac rhythm;

a plurality of independent rhythm discriminators configured to classify the cardiac rhythm, the plurality of discriminators including a morphology-based rhythm discriminator that utilizes a correlation threshold parameter; and

a classification processor coupled to the independent rhythm discriminators, the classification processor configured to implement a classification process to classify the cardiac rhythm, the classification process based on results of the independent rhythm discriminators, the classification processor further configured to determine if modification of the classification process is likely to enhance rhythm classification and to modify, if the rhythm classification is likely to be enhanced, the classification process by changing the correlation threshold parameter of the morphology-based rhythm discriminator, wherein the classification processor is further configured to modify a first parameter of a first rhythm discriminator based on a second parameter of a second rhythm discriminator and to reclassify the cardiac rhythm using the modified classification process.

27. A cardiac device, comprising:

a sensing circuit configured to implantably sense cardiac signals associated with a cardiac rhythm;

a plurality of independent rhythm discriminators configured to classify the cardiac rhythm, the plurality of discriminators including a morphology-based rhythm discriminator that utilizes a correlation threshold parameter;

a metabolic sensor configured to determine information associated with a patient'"'"'s metabolic need; and

a classification processor coupled to the independent rhythm discriminators, the classification processor configured to implement a classification process to classify the cardiac rhythm, the classification process based on results of the independent rhythm discriminators, the classification processor further configured to determine if modification of the classification process is likely to enhance rhythm classification and to modify, if the rhythm classification is likely to be enhanced, the classification process using the metabolic information by changing the correlation threshold parameter of the morphology-based rhythm discriminator, the classification processor further configured to reclassify the cardiac rhythm using the modified classification process.