Cardiac rhythm management system with maximum tracking rate (MTR) hysteresis

• US 7,869,875 B2
• Filed: 05/06/2005
• Issued: 01/11/2011
• Est. Priority Date: 11/06/2001
• Status: Expired due to Fees

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Kramer, Andrew P.
• Primary Examiner(s): Evanisko; George R
• Assistant Examiner(s): STOKLOSA, JOSEPH A
• Application Number:
  US11/123,813
• Publication Number:
  US 20050288723A1
• Time in Patent Office: 2,076 Days
• Field of Search: 607/9, 607/14
• US Class Current: 607/14
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/3684 for stimulating the heart at multiple sites of the ventricle or the atrium
• CPC Class Codes: A61N 1/36843 Bi-ventricular stimulation

Abstract

A cardiac rhythm management system provides both a safe maximum pacing rate limit and a physiological maximum pacing rate limit. In one embodiment, a normal maximum tracking rate (MTR) and a hysteresis MTR are provided. The hysteresis MTR is set higher than the normal MTR and functions as a maximum pacing rate. When an atrial rate exceeds the hysteresis MTR limit, the maximum pacing rate limit is set to the normal MTR. Once the atrial rate falls below a predetermined threshold, the maximum pacing rate limit is set to the hysteresis MTR. This provides for a more rapid and natural maximum pacing rate limit for a patient, while still protecting the patient from being paced at abnormally high rates.

Claims

1. A method, including:

sensing a first cardiac signal from an atrial location;

detecting atrial depolarizations from the first cardiac signal;

determining an atrial rate based on the atrial depolarizations;

comparing the atrial rate to a predetermined threshold and a second predetermined value;

setting a maximum ventricular pacing rate in a cardiac rhythm management device using a result of the comparing, the setting including;

setting the maximum ventricular pacing rate to a first predetermined value when the atrial rate exceeds the second predetermined value, the second predetermined value larger than the first predetermined value; and

setting the maximum ventricular pacing rate to the second predetermined value when the atrial rate falls below the predetermined threshold.

2. The method of claim 1, wherein the maximum ventricular pacing rate is a maximum tracking rate (MTR).

3. The method of claim 1, wherein the predetermined threshold is set to the first predetermined value.

4. The method of claim 1, wherein the predetermined threshold is set to the second predetermined value.

5. The method of claim 1, wherein setting the maximum ventricular pacing rate to the first predetermined value when the atrial rate exceeds the second predetermined value includes changing the maximum ventricular pacing rate from the second predetermined value to the first predetermined value over a predetermined time interval.

6. The method of claim 1, further including:

setting the PVARP to a first set value when the maximum ventricular pacing rate is set to the first predetermined value; and

setting the PVARP to a second set value when the maximum ventricular pacing rate is set to the second predetermined value.

7. The method of claim 6, further including:

calculating the first predetermined value based on at least the first set value and an atrioventricular pacing delay (AV delay); and

calculating the second predetermined value based on at least the second set value and the AV delay.

8. The method of claim 6, further including:

calculating the first predetermined value based on at least the first set value, an AV delay, and a first sensing window interval; and

calculating the second predetermined value based on at least the second set value, the AV delay, and a second sensing window interval.

9. The method of claim 8, wherein:

the first sensing window interval is a predetermined percentage of a sum of the first set value and the AV delay; and

the second sensing window interval is a predetermined percentage of a sum of the second set value and the AV delay.

10. The method of claim 8, wherein the sensing window interval is a programmable value being a function of at least one of the first and second predetermined values.

11. The method of claim 6, further including extending the PVARP associated with the first predetermined value for at least one cardiac cycle length after setting the maximum ventricular pacing rate to the first predetermined value when the atrial rate exceeds the second predetermined value.

12. The method of claim 6, further including calculating the second predetermined value from the PVARP and an AV delay.

13. The method of claim 1, further including ignoring any atrial depolarization and not triggering an AV delay for one cardiac cycle every N cardiac cycles when the atrial rate exceeds the first predetermined value.

14. The method of claim 1, further including setting the maximum ventricular pacing rate to the first predetermined value when an atrial depolarization is sensed during a postventricular atrial refractory period (PVARP).

15. The method of claim 1, further including setting the maximum ventricular pacing rate to the first predetermined value when at least a predetermined number of atrial depolarizations are sensed during postventricular atrial refractory periods (PVARPs) over a predetermined number of consecutive cardiac cycles.

16. The method of claim 1, further including:

delivering ventricular pacing pulses; and

setting the maximum ventricular pacing rate to the first predetermined value when the ventricular pacing pulses are delivered at a rate equal to the second predetermined value.

17. A method, including:

sensing a first cardiac signal from a ventricular location;

detecting ventricular depolarizations from the first cardiac signal;

determining a heart rate based on the ventricular depolarizations;

comparing the heart rate to a first predetermined value and a second predetermined value, the second value larger than the first value;

setting a maximum atrial pacing rate in a cardiac rhythm management device to the first predetermined value when the heart rate exceeds the second predetermined value; and

setting the maximum atrial pacing rate in a cardiac rhythm management device to the second predetermined value when the heart rate falls below a predetermined threshold.

18. The method of claim 17, wherein the predetermined threshold is set to the first predetermined value.

19. The method of claim 17, wherein the predetermined threshold is set to the second predetermined value.

20. A method, including:

sensing a first cardiac signal from an atrial location;

detecting atrial depolarizations from the first cardiac signal;

determining a heart rate based on the atrial depolarizations;

comparing the heart rate to a first predetermined value and a second predetermined value, the second value larger than the first value;

setting a maximum atrial pacing rate in a cardiac rhythm management device to the first predetermined value when the heart rate exceeds the second predetermined value; and

setting the maximum atrial pacing rate in a cardiac rhythm management device to the second predetermined value when the heart rate falls below a predetermined threshold.

21. The method of claim 20, wherein the predetermined threshold is set to the first predetermined value.

22. The method of claim 20, wherein the predetermined threshold is set to the second predetermined value.