Ventricular pacing to augment atrial natriuretic hormone production

1. A method, comprising:

monitoring a first physiological parameter of a subject in a first operating mode;

detecting whether the first physiological parameter meets a first criteria for triggering use of a second operating mode by a cardiac rhythm management device; and

responding to detecting that the first physiological parameter meets the first criteria by switching the cardiac rhythm management device from the first operating mode to the second operating mode, the second operating mode configured to time delivery of a pace so that delivery of the pace results in a substantial overlap of ventricular systole and atrial systole.

2. The method of claim 1 , wherein the first operating mode includes a first therapy delivery mode, and the second operating mode includes an atrial stretch therapy mode.

3. The method of claim 1 , wherein the second operating mode is configured to time delivery of a pace so that deliver of the pace results in a ventricular contraction occurs before or substantially concurrent with an atrial contraction during the same cardiac cycle.

4. The method of claim 1 , further including:

monitoring a second physiological parameter of the subject; and

responding to detecting that the first physiological parameter meets the first criteria value by detecting whether the second physiological parameter meets a second criteria for limiting use of the second operating mode.

5. The method of claim 4 , further including:

responding to detecting that the second physiological parameter meets the second criteria by maintaining the cardiac rhythm management device in the first operating mode and avoid switching to the second operating mode.

6. The method of claim 1 , wherein the processor is configured to time delivery of the pace, when in the second operating mode, to cause atrioventricular valve closure during at least one of:

early atrial systole or a specified period of time before atrial systole.

7. The method of claim 1 , further including:

a cardiac pacing circuit coupled to the processor and configured to deliver the pace to a chamber of a heart, wherein the processor is configured to time delivery of the pace, when in the second operating mode, so the ventricular contraction occurs before the atrial contraction during the same cardiac cycle.

8. The method of claim 1 , further including:

a cardiac pacing circuit coupled to the processor and configured to deliver the pace to a chamber of a heart, wherein the processor is configured to time delivery of the pace, when in the second operating mode, so the ventricular contraction occurs substantially concurrent with the atrial contraction during the same cardiac cycle.

9. The method of claim 1 , further including:

adjusting use of the second operating mode using information about the measure of the first physiologic parameter.

10. The method of claim 9 , wherein the first physiologic parameter includes at least one of:

systemic blood pressure, cardiac output, or fluid status.

11. An apparatus comprising:

a cardiac rhythm management device including:

a cardiac pacing circuit configured to deliver a pacing pulse to a chamber of a heart; and

a processor, coupled to the cardiac pacing circuit, the processor configured to include a first operating mode and a second operating mode, the processor configured to:

switch from the first operating mode to the second operating mode based upon a triggering event; and

time delivery of the pacing pulse to the chamber of the heart, when in the second operating mode, so that delivery of the pacing pulse results in a substantial overlap of ventricular systole and atrial systole.

12. The apparatus of claim 11 , wherein the first operating mode includes a first therapy delivery mode, and the second operating mode includes an atrial stretch therapy mode.

13. The apparatus of claim 11 , wherein the processor is configured to time delivery of the pacing pulse to the chamber of the heart, when in the second operating mode, so that a ventricular contraction occurs before or substantially concurrent with an atrial contraction during the same cardiac cycle.

14. The apparatus of claim 11 , further including:

a physiologic sensor, coupled to the processor, the physiologic sensor configured to measure a physiologic parameter of a subject;

wherein the triggering event at least partially includes when the measure of the physiologic parameter meets a specified threshold value, and wherein the processor is configured to adjust use of the second operating mode using information about the measure of the physiologic parameter.

15. The apparatus of claim 11 , further including:

a physical activity sensor, coupled to the processor, the physical activity sensor configured to detect physical activity of a subject;

wherein the triggering event at least partially includes when the measure of the physical activity is above a specified threshold value.

16. The apparatus of claim 11 , further including:

a cardiac output monitor circuit, coupled to the processor, the cardiac output monitor circuit configured to provide an indication of a cardiac output of a subject; and

wherein the triggering event at least partially includes when the indication of the cardiac output is below a specified threshold value.

17. The apparatus of claim 11 , wherein, when in the second operating mode, the processor is configured to deliver the pacing pulse intermittently, including at least one of:

delivering the pacing pulse a specified number of times per a specified number of cycles;

delivering the pacing pulse a specified number of times per a specified time period; or

delivering one or more pacing pulse sessions over a time period.

18. The apparatus of claim 11 , wherein the processor is configured to limit use of the second operating mode when the first physiological data meets a first criteria.

19. The apparatus of claim 18 , wherein the processor is configured to:

detect, based on the systemic blood pressure of the subject, an atrial event; and

time delivery of the pacing pulse, when in the second operating mode, so that the pacing pulse is synchronized to the systemic blood pressure.

20. The apparatus of claim 18 , wherein the processor is configured to:

receive second physiological data about the subject; and

limit use of the second operating mode when the second physiological data meets a second criteria.