System And Method For Determining The Origin Of A Sensed Beat

• US 20080281369A1
• Filed: 05/08/2007
• Published: 11/13/2008
• Est. Priority Date: 05/08/2007
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Girouard, Steven D., KenKnight, Bruce
• Granted Patent: US 8,442,631 B2
• Time in Patent Office: Days
• US Class Current: 607/9
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/29 for permanent or long-term implantation
• CPC Class Codes: A61B 5/35 by template matching
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371

Abstract

A method for monitoring a biological cardiac pacemaker is provided. The method may include stimulating a heart at a region selected for implantation of a biological pacemaker and sensing at least one electrical signal indicative of a cardiac depolarization originating in the region selected for implantation of the biological pacemaker. The method may further include sensing at least one subsequent electrical signal produced by the heart and determining if the subsequent electrical signal originated in the region selected for the biological pacemaker or another region of the heart. In an alternative embodiment, the method may include determining a template time difference between two points on cardiac complexes sensed in two or more different cardiac locations during normal sinus rhythm. The method may further include determining a time difference between two points on a subsequent cardiac complex sensed in two or more different cardiac locations. The time differences may be compared to determine if the subsequently-sensed cardiac complex originates in a left ventricular biological pacemaker site or in another cardiac site.

Claims

1. A method for monitoring a biological cardiac pacemaker, comprising:

stimulating a heart at a region selected for implantation of a biological pacemaker;

sensing at least one electrical signal indicative of a cardiac depolarization originating in the region selected for implantation of the biological pacemaker;

sensing at least one subsequent cardiac complex produced by the heart; and

determining if the subsequent cardiac complex originated in the region selected for the biological pacemaker or another region of the heart.

2. The method of claim 1, wherein determining if the subsequently-sensed cardiac complex originated in the region selected for implantation of a biological pacemaker includes:

determining a template waveform representative of a cardiac depolarization originating at the region selected for implantation of the biological pacemaker; and

comparing the subsequently-sensed cardiac complex produced by the heart with the template waveform.

3. The method of claim 2, wherein comparing the electrical signal produced by the heart with the template waveform includes:

selecting a first predetermined feature of the template waveform;

selecting a predetermined feature of a subsequently-sensed cardiac complex;

aligning the predetermined feature of the template waveform with the predetermined waveform of the subsequently-sensed cardiac complex;

comparing the template waveform to the subsequently-sensed cardiac complex; and

determining if the subsequently-sensed cardiac complex originated in the region selected for the biological pacemaker.

4. The method of claim 1, wherein determining if the subsequently-sensed cardiac complex originated in the region selected for the biological pacemaker or another region of the heart includes:

determining a template cardiac vector from the cardiac complex originating in the region selected for implantation of the biological pacemaker; and

determining a subsequent cardiac vector from the at least one subsequent cardiac complex produced by the heart.

5. The method of claim 4, further including comparing the template cardiac vector to the at least one subsequent cardiac vector.

6. The method of claim 5, wherein comparing the template cardiac vector to the at least one subsequent cardiac vector includes:

determining a region surrounding the template cardiac vector; and

determining if the subsequent cardiac vector is within the region surrounding the template cardiac vector.

7. The method of claim 4, wherein the template cardiac vector comprises two or more scalar values representing repeatably identifiable features of sensed cardiac signals.

8. The method of claim 7, wherein the repeatably identifiable features include at least one of a beginning of a cardiac depolarization, an end of a cardiac depolarization, a slew rate, a slope, and a maximum deflection.

9. The method of claim 7, wherein the repeatably identifiable features include at least one cardiac interval.

10. The method of claim 9, wherein the interval includes a time interval between a point within a cardiac signal sensed in a first cardiac channel and a point within a cardiac signal sensed in a second cardiac channel.

11. The method of claim 9, wherein the interval includes a time interval between two points within a cardiac signal sensed in a single cardiac channel.

12. The method of claim 1, wherein determining if the subsequent cardiac complex originated in the region selected for the biological pacemaker or another region of the heart comprises:

determining a template morphology for a cardiac complex originating in a cardiac region corresponding to the region selected for the biological pacemaker;

comparing a morphology of the cardiac complex in the first cardiac signal to a first template morphology and comparing the morphology of the cardiac complex in the second cardiac signal to a second template morphology; and

classifying the cardiac complex as either originating in a biological pacemaker or another cardiac location based on the comparison of the morphology of the cardiac complex in the first cardiac signal and the second cardiac signal to the first template morphology and the second template morphology.

13. The method of claim 1, wherein determining if the subsequent cardiac complex originated in the region selected for the biological pacemaker or another region of the heart comprises:

monitoring a first signal and a second signal representative of cardiac electrical activity;

detecting a NSR cardiac complex in each of the first signal and the second signal;

detecting at least one additional cardiac complex in each of the first signal and the second signal;

locating a predetermined feature in the cardiac complex detected in the first signal and a first NSR representative complex, wherein the predetermined feature includes a repeatably identifiable complex section common to the cardiac complex detected in the first signal and the first NSR representative complex;

aligning the predetermined feature in the at least one additional cardiac complex detected in the first signal and the first NSR representative complex;

comparing the at least one additional cardiac complex detected in the second signal to a second NSR representative complex; and

classifying the cardiac complex as a ventricular biologic pacemaker complex based on the comparison of the morphology of the cardiac complex in the second cardiac signal to the second NSR representative complex.

14. An implantable medical device for monitoring an implantable biologic pacemaker, comprising:

a first sensing system for detecting a cardiac signal at a first location;

a second sensing system for detecting a cardiac signal at a second location; and

a processor unit configured to compare information derived from sensed cardiac signals from the first sensing system and second sensing system with at least one template cardiac signal and to determine if the sensed cardiac signals originated in the location of a biological cardiac pacemaker.

15. The device of claim 14, further including at least one pacing lead configured to provide cardiac stimulating pulses for pacing a heart.

16. The device of claim 15, wherein the device is configured to provide cardiac pacing with a predetermined lower rate limit and to periodically decrease the lower rate limit to evaluate pacing by the biological pacemaker.

17. The device of claim 16, wherein the decrease in the lower rate limit occurs at predetermined intervals.

18. The device of claim 16, wherein the decrease in the lower rate limit is initiated by a patient or physician.

19. The device of claim 14, further including at least one defibrillation circuit configured to provide cardiac defibrillation or cardioverting shocks.

20. The device of claim 14, further including at least one pacing lead and pacing circuit configured to provide cardiac resynchronization therapy.

21. A device of claim 14, further comprising:

a template generator circuit coupled to at least one of the first sensing system and second sensing system, wherein the template generator circuit determines a first NSR representative complex and a second NSR representative complex from a plurality cardiac complexes sensed during normal sinus rhythm;

a morphology analyzer circuit coupled to the sensing system, where the morphology analyzer circuit locates a predetermined feature in a cardiac complex detected in the first signal and in the first NSR representative complex, wherein the predetermined feature includes a repeatably identifiable complex section common to the cardiac complex detected in the first signal and the first NSR representative complex; and

a signal feature comparison circuit coupled to the morphology analyzer circuit and the template generator circuit, wherein the signal feature comparison circuit aligns the predetermined feature in the cardiac complex monitored in the first signal with the predetermined feature on the first NSR representative complex and compares the cardiac complex monitored in the second signal to the second NSR representative complex to determine whether the cardiac complex originated in a ventricular biological pacemaker complex.

22. The device of claim 14, further comprising:

a morphology analyzer circuit coupled to at least one of the first sensing system and the second sensing system, wherein the morphology analyzer circuit locates a position of at least one predetermined feature in the morphology of the cardiac complex in the first signal and the second signal and generates two or more scalar values as a function of the position of the at least one predetermined feature for each of the first signal and the second signal;

a template generator coupled to the morphology analyzer, wherein the template generator circuit creates a cardiac complex vector from the two or more scalar values generated by the morphology analyzer circuit; and

a signal feature comparison circuit coupled to the morphology analyzer circuit and the template generator circuit, wherein the signal feature comparison circuit compares the cardiac complex vector to one or more classification vectors to determine if the a sensed cardiac complex originated in a ventricular biological pacemaker complex

23. A method for monitoring a biological cardiac pacemaker, comprising:

implanting a biologic pacemaker in a ventricle of a heart;

monitoring two or more cardiac channels configured to detect electrical signals representative of cardiac depolarization;

detecting a cardiac complex in each of the two or more cardiac channels during a depolarization originating in a supraventricular location;

determining a template time difference between two repeatably identifiable features on at least one of the two or more cardiac signals;

detecting at least one additional cardiac complex in each of the two or more cardiac channels subsequent to implantation of the biological pacemaker;

determining a second time difference between two repeatably identifiable features on at least one of the additional cardiac complexes; and

determining if the subsequent cardiac complex originated in the region selected for the ventricular biological pacemaker or another region of the heart.

24. The method of claim 23, wherein the repeatably identifiable features include at least one of a beginning of a cardiac depolarization, an end of a cardiac depolarization, a slew rate, a slope, and a maximum deflection.

25. The method of claim 24, wherein the repeatably identifiable features include at least one cardiac interval.

26. The method of claim 25, wherein the interval includes a time interval between a point within a cardiac signal sensed in a first cardiac channel and a point within a cardiac channel sensed in a second cardiac channel.

27. The method of claim 25, wherein the interval includes a time interval between two points within a cardiac signal sensed in a single cardiac channel.