Method and apparatus for using heart rate variability to control maximum tracking rate in pacing therapy

• US 20060161210A1
• Filed: 01/18/2005
• Published: 07/20/2006
• Est. Priority Date: 01/18/2005
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Carlson, Gerrard M., Pastore, Joseph M., Yu, Yinghong, Ding, Jiang, Kramer, Andrew P., Salo, Rodney W.
• Granted Patent: US 7,580,745 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/4035 Evaluating the autonomic nervous system
• CPC Class Codes: A61N 1/36114 Cardiac control, e.g. by vagal stimulation stimulating the heart A61N1/362
• CPC Class Codes: A61N 1/36592 controlled by the heart rate variability
• CPC Class Codes: A61N 1/368 comprising more than one electrode co-operating with different heart regions A61N1/3622, A61N1/3627 take precedence

Abstract

A cardiac rhythm management system modulates the delivery of pacing and/or autonomic neurostimulation pulses based on heart rate variability (HRV). An HRV parameter being a measure of the HRV is produced to indicate a patient'"'"'s cardiac condition, based on which the delivery of pacing and/or autonomic neurostimulation pulses is started, stopped, adjusted, or optimized. In one embodiment, the HRV parameter is used to adjust a maximum tracking rate in an atrial tracking pacing mode.

Claims

1. A cardiac rhythm management system, comprising:

a pacing output circuit to deliver pacing pulses;

a sensing circuit to sense a cardiac signal;

a heart rate variability (HRV) measurement circuit, coupled to the sensing circuit, to measure an HRV being a variance in cardiac cycle lengths over a predetermined period of time based on the sensed cardiac signal and to produce an HRV parameter based on the HRV measurement; and

a pacing control circuit coupled to the pacing output circuit, the sensing circuit, and the HRV measurement circuit, the pacing control circuit including;

a pacing algorithm execution module to control the delivery of the pacing pulses by executing an atrial tracking pacing algorithm using pacing parameters including a maximum tracking rate (MTR); and

an MTR adjustment module coupled to the HRV measurement circuit and the pacing algorithm execution module, the MTR adjustment circuit adapted to adjust the MTR based on the HRV parameter.

2. The system of claim 1, wherein the cardiac signal comprises an electrogram.

3. The system of claim 2, wherein the pacing algorithm execution module comprises a bradycardia pacing algorithm execution module.

4. The system of claim 2, wherein the pacing algorithm execution module comprises a cardiac resynchronization therapy (CRT) pacing algorithm execution module.

5. The system of claim 2, wherein the pacing algorithm execution module comprises a remodeling control therapy (RCT) pacing algorithm execution module.

6. The system of claim 2, wherein the MTR adjustment module comprises an MTR selector adapted to select a value for the MTR from a plurality of predetermined values based on the HRV parameter.

7. The system of claim 6, wherein the MTR selector comprises a comparator to compare the HRV parameter to a threshold HRV level, and wherein the MTR selector is adapted to set the MTR to a predetermined first value if the HRV parameter exceeds the predetermined threshold and a predetermined second value if the HRV parameter does not exceed the threshold HRV level.

8. The system of claim 7, wherein the MTR adjustment module further comprises an HRV threshold generator to dynamically adjust the threshold HRV level based on an activity level.

9. The system of claim 1, wherein the HRV measurement circuit comprises one or more of a Standard Deviation of Normal-to-Normal intervals (SDNN) generator to produce an SDNN, a Standard Deviation of Averages of Normal-to-Normal intervals (SDANN) generator to produce an SDANN, a Ratio of Low Frequency HRV to High Frequency HRV ratio (LF/HF ratio) generator to produce an LF/HF ratio, an HRV footprint generator to produce an HRV footprint, and a Root-Mean-Square of Successive Differences (RMSSD) generator to produce an RMSSD.

10. The system of claim 1, wherein the HRV measurement circuit comprises an autonomic balance monitor to monitor a parameter indicative of a balance between sympathetic and parasympathetic activities.

11. The system of claim 10, wherein the autonomic balance monitor comprises a Ratio of Low Frequency HRV to High Frequency HRV ratio (LF/HF ratio) generator to produce an LF/HF ratio.

12. A method for operating a cardiac pacemaker, comprising:

sensing a cardiac signal;

measuring a variance in cardiac cycle lengths over a predetermined period of time to produce a heart rate variability (HRV) parameter based on the sensed cardiac signal;

executing an atrial tracking pacing algorithm to control pacing pulse deliveries, the atrial tracking pacing algorithm using pacing parameters including a maximum tracking rate (MTR); and

adjusting the MTR based on the HRV parameter.

13. The method of claim 12, wherein sensing a cardiac signal comprises sensing an electrogram.

14. The method of claim 13, wherein executing the atrial tracking pacing algorithm comprises executing one of a bradycardia pacing algorithm, a CRT pacing algorithm, and a post-MI RCT pacing algorithm.

15. The method of claim 14, wherein adjusting the MTR based on the HRV parameter comprising setting the MTR to one of a plurality of predetermined values based on the HRV parameter.

16. The method of claim 15, wherein setting the MTR to one of the plurality of predetermined values based on the HRV parameter comprises:

comparing the HRV parameter to a threshold HRV level; and

setting the MTR to a first value if the HRV parameter exceeds the threshold HRV level and a second value if the HRV parameter does not exceed the threshold HRV level.

17. The method of claim 16, further comprising dynamically adjusting the threshold HRV level based on a heart rate.

18. The method of claim 16, further comprising dynamically adjusting the threshold HRV level based on an indication, estimation, or prediction of an activity level.

19. The method of claim 12, wherein measuring HRV to produce the HRV parameter comprises measuring HRV to produce one or more of a Standard Deviation of Normal-to-Normal intervals (SDNN), a Standard Deviation of Averages of Normal-to-Normal intervals (SDANN), a Ratio of Low Frequency HRV to High Frequency HRV ratio (LF/HF ratio), an HRV footprint, and a Root-Mean-Square of Successive Differences (RMSSD).

20. The method of claim 12, wherein measuring HRV to produce the HRV parameter comprises measuring HRV to produce a parameter indicative of a balance between sympathetic and parasympathetic activities.

21. The method of claim 20, wherein measuring HRV to produce the parameter indicative of the balance between sympathetic and parasympathetic activities comprises producing a Ratio of Low Frequency HRV to High Frequency HRV ratio (LF/HF ratio).