Automated Template Generation Algorithm for Implantable Device

• US 20060270937A1
• Filed: 05/26/2006
• Published: 11/30/2006
• Est. Priority Date: 04/25/2001
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Gillberg, Jeffrey M., Cao, Jian, Koyrakh, Lev A., Davydov, Eugene
• Granted Patent: US 7,640,054 B2
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 5/35 by template matching

Abstract

A method of generating a template in an implantable medical device for implantation within a patient, and a processor readable medium for performing the method, that includes generating a template from collected events corresponding to the patient, delaying the generation of the template for a first predetermined time period in response to the template not being generated within a predetermined number of collected events, determining whether the template is valid, and monitoring the template to determine whether the template is an accurate representation of the patient.

Claims

1. A method of generating a template in an implantable medical device for implantation within a patient, comprising the steps of:

generating a template from collected events corresponding to the patient;

delaying the step of generating a template for a first predetermined time period in response to the template not being generated within a predetermined number of collected events;

determining whether the template is valid; and

monitoring the template to determine whether the template is an accurate representation of the patient.

2. The method of claim 1, wherein the first predetermined time period is approximately 10 minutes and the predetermined number of collected events is 64.

3. The method of claim 1, further comprising the steps of:

generating a new template in response to the template not being an accurate representation; and

continuing to monitor the template in response to the template being an accurate representation.

4. The method of claim 1, wherein the step of generating a template comprises the steps of:

monitoring a heart rate of the patient to generate the collected events;

determining whether beats corresponding to the collected events are normal beats; and

determining whether a predetermined number of normal beats has been collected within the predetermined number of collected events.

5. The method of claim 4, wherein the step of delaying the template generation includes delaying the template generation in response to the predetermined number of normal beats not being collected within the predetermined number of collected events.

6. The method of claim 5, wherein the step of generating a template further comprises:

determining whether the predetermined number of normal beats have been collected and computing cross matches between the predetermined number of collected normal beats to form corresponding computed cross matches;

determining whether a predetermined number of the computed cross matches exceed a threshold;

determining whether a predetermined number of cross matching attempts have failed;

delaying the template generation for a second predetermined time period in response to the predetermined number of failed cross matching attempts; and

forming the template from the predetermined number of computed cross matches in response to the predetermined number of the computed cross matches exceeding the threshold.

7. The method of claim 6, wherein the predetermined number of cross matches is four and the second predetermined time period is approximately equal to 156 minutes.

8. The method of claim 4, wherein the step of determining whether beats corresponding to the collected events are normal beats includes excluding beats having R-R intervals greater than a predetermined R-R interval.

9. The method of claim 8, wherein the predetermined R-R interval is approximately 85% of an average R-R interval.

10. The method of claim 6, wherein the predetermined number of beats is six and the predetermined number of computed cross matches is four.

11. The method of claim 1, wherein the step of determining whether the template is valid comprises the steps of:

collecting subsequent normal beats within a second predetermined time period;

computing a match between the subsequently collected normal beats and the template;

determining whether the match is within a predetermined threshold to form matched beats and other than matched beats;

determining whether the other than matched beats is greater than a first number of beats; and

determining the template is valid in response to the matched beats being greater than or equal to a second number of beats.

12. The method of claim 11, wherein the step of collecting subsequent normal beats comprises collecting one normal beat within 10 seconds.

13. The method of claim 11, wherein, in response to the other than matched beats being greater than the first number of beats, the step of determining whether the template is valid further comprises the step of:

determining whether attempts to validate the template have failed a predetermined number of times;

repeating the step of generating a template in response to validation of the template not having failed the predetermined number of times; and

delaying the step of determining whether the template is valid for a third predetermined time period in response to validation of the template having failed the predetermined number of times.

14. The method of claim 13, wherein the third predetermined time period is approximately equal to 9 hours and the predetermined number of times is three.

15. The method of claim 11, wherein the first number of beats is thirty and the second number of beats is seventy.

16. The method of claim 11, further comprising, in response to the matched beats not being greater than or equal to the second number of beats, the steps of:

determining whether a match has been computed for a predetermined number of beats;

determining whether a time period has been exceeded in response to the match not being computed for the predetermined number of beats; and

repeating the step of generating a template in response to the predetermined time period being exceeded.

17. The method of claim 16, wherein the first number of beats is thirty, the second number of beats is seventy, and the predetermined number of beats is one hundred.

18. The method of claim 1, wherein the step of monitoring the template comprises the steps of:

(a) collecting subsequent normal beats within a second predetermined time period;

(b) computing a match between a subsequently collected beat and the template;

(c) determining whether the match is within a predetermined threshold to form matched beats and other than matched beats;

(d) determining whether x out of the last y subsequently collected beats are other than matched beats; and

(e) repeating steps (a)-(d) in response to x out of the last y beats not being other than matched beats.

19. The method of claim 18, wherein step (a) comprises collecting one normal beat every 1000 seconds.

20. The method of claim 18, wherein the step of computing a match comprises computing the match for one out of every one thousand subsequently collected beats and the template

21. The method of claim 18, further comprising the step of repeating the step of generating a template in response to x out of the last y beats being other than matched beats.

22. The method of claim 18, further comprising, in response to x out of the last y beats being other than matched beats, the steps of:

determining whether an average degree of similarity between the other than matched beats and the template is less than a predetermined threshold;

deleting the template in response to the average degree of similarity between the other than matched beats and the template being less than the predetermined threshold; and

generating a template in response to the average degree of similarity between the other than matched beats and the template being greater than or equal to the predetermined threshold.

23. The method of claim 18, wherein x is thirty and y is one hundred.

24. A processor readable medium in an implantable medical device, comprising:

means for collecting events corresponding to the patient; and

means for generating a template corresponding from the collected events, the means for generating a template further delaying the template generation for a first predetermined time period in response to the template not being generated within a predetermined number of the collected events, determining whether the template is valid and monitoring the template to determine whether the template is an accurate representation of the supraventricular rhythm.

25. The processor readable medium of claim 24, wherein the generating means generates a new template in response to the template not being an accurate representation;

and

continues to monitor the template in response to the template being an accurate representation

26. The processor readable medium of claim 24, wherein the generating means monitors a heart rate of the patient to generate the collected events, determines whether beats corresponding to the collected events are normal beats, and determines whether a predetermined number of normal beats has been collected within the predetermined number of collected events.

27. The processor readable medium of claim 24, wherein the generating means determines whether a predetermined number of normal beats have been collected and computes cross matches between the predetermined number of collected normal beats to form corresponding computed cross matches, determines whether a predetermined number of the computed cross matches exceed a threshold, determines whether a predetermined number of cross matching attempts have failed, delays the template generation for a second predetermined time period in response to the predetermined number of failed cross matching attempts, and forms the template from the predetermined number of computed cross matches in response to the predetermined number of the computed cross matches exceeding the threshold.

28. The processor readable medium of claim 24, wherein the generating means determines whether attempts to validate the template have failed a predetermined number of times, generates a new a template in response to validation of the template not having failed the predetermined number of times, and delays determination of whether the template is valid for a second predetermined time period in response to validation of the template having failed the predetermined number of times

29. The processor readable medium of claim 24, wherein the generating means determines whether an average degree of similarity between the other than matched beats and the template is less than a predetermined threshold, deletes the template in response to the average degree of similarity between the other than matched beats and the template being less than the predetermined threshold, and generates a template in response to the average degree of similarity between the other than matched beats and the template being greater than or equal to the predetermined threshold.