Systems and methods for detecting device dislodgment

1. A method for determining a dislodgement status of an implantable device at an implant site on the heart of a patient, the implantable device having an accelerometer for providing an accelerometer signal, the method comprising:

collecting, by the implantable device operating in a first operating mode, a first number of discrete accelerometer signal samples during a first portion of a cardiac cycle of the heart and using the first number of discrete accelerometer signal samples to determine a first patient parameter, wherein the first portion of the cardiac cycle beginning after a repolarization of the heart during the cardiac cycle and ending before a subsequent polarization of the heart;

collecting, by the implantable device operating in a second operating mode, a second number of discrete accelerometer signal samples during a second portion of a cardiac cycle of the heart and using the second number of discrete accelerometer signal samples to determine a dislodgment status of the implantable device, wherein the second portion of the cardiac cycle including at least part of a polarization of the heart during the cardiac cycle, wherein the first number is smaller than the second number; and

providing a notification of the dislodgment status to a remote device that is remote from the implantable medical device.

2. The method of claim 1 , wherein the implantable device is a leadless cardiac pacemaker.

3. The method of claim 1 , wherein the first patient parameter is used by the implantable device to affect a therapy delivered by the implantable device.

4. The method of claim 1 , wherein the first patient parameter comprises one of:

a posture; and

an activity level.

5. The method of claim 1 , wherein the first patient parameter represents an activity level of the patient, and is used by the implantable device to affect a pacing rate of a pacing therapy delivered by the implantable device to the heart of the patient.

6. The method of claim 1 , wherein the implantable device collects the discrete accelerometer signal samples by selectively turning on and off the accelerometer of the implantable device.

7. The method of claim 1 , wherein the first portion and the second portion are of the same cardiac cycle.

8. The method of claim 7 , wherein the first portion and the second portion are of different cardiac cycles.

9. A leadless cardiac pacemaker (LCP) comprising:

a plurality of electrodes;

an accelerometer; and

a controller operatively coupled to the plurality of electrodes and the accelerometer, the controller configured to:

determine a patient parameter based at least in part on a first amount of accelerometer data collected during a first portion of a cardiac cycle that does not include a contraction of a heart;

determine a dislodgment status of the leadless cardiac pacemaker based at least in part on a second amount of accelerometer data collected during a second portion of a cardiac cycle that includes at least part of a contraction of the heart, wherein the first amount of accelerometer data is less than the second amount of accelerometer data; and

communicate the dislodgment status to a remote device that is remote from the leadless cardiac pacemaker.

10. The LCP of claim 9 , wherein the first amount of accelerometer data and the second amount of accelerometer data are collected during the same cardiac cycle.

11. The LCP of claim 9 , wherein the patient parameter is used by the leadless cardiac pacemaker to affect a therapy delivered by the leadless cardiac pacemaker.

12. The LCP of claim 9 , wherein the patient parameter comprises one of:

a posture; and

a patient activity level.

13. The LCP of claim 9 , wherein a beginning of the first portion of the cardiac cycle and a beginning of the second portion of the cardiac cycle are offset by different amounts relative to a common detected R-wave.

14. A method comprising:

detecting, by a leadless cardiac pacemaker (LCP) having an accelerometer, an occurrence of a cardiac electrical event;

collecting, by the LCP, accelerometer signal data during a first time period of a cardiac cycle, wherein the first time period begins a first predetermined amount of time after the detected cardiac electrical event and wherein the first time period does not include a contraction of a heart;

collecting, by the LCP, accelerometer signal data during a second time period of a cardiac cycle, wherein the second time period begins a second predetermined amount of time after the detected cardiac electrical event and wherein the second time period does include at least part of the contraction of the heart; and

determining, by the LCP, a dislodgment status of the LCP based at least in part on the accelerometer signal data collected during the second time period.

15. The method of claim 14 , wherein the cardiac electrical event an R-wave.

16. The method of claim 15 , wherein the first time period begins between 300 ms and 800 ms after the detected R-wave.

17. The method of claim 16 , wherein the second time period begins between 0 ms and 50 ms after the detected R-wave.

18. The method of claim 14 , wherein the first time period and the second time period are of different cardiac cycles.