Method and apparatus for adjusting a sensing parameter

1. A method of determining oversensing in a medical device, comprising:

sensing cardiac signals;

determining an oversensing characteristic associated with cardiac signals sensed during a predetermined sensing window, wherein the predetermined sensing window comprises a predetermined duration of time unrelated to one or more beat-to-beat durations;

identifying oversensing in response to the oversensing characteristic;

determining, in response to oversensing being identified, an adjusting characteristic associated with cardiac signals sensed during the predetermined sensing window; and

updating a sensing parameter in response to the determined adjusting characteristic.

2. The method of claim 1 , wherein the cardiac signals are sensed from a non-transvenous location.

3. The method of claim 1 , wherein determining an oversensing characteristic includes determining a first oversensing characteristic and a second oversensing characteristic, the first oversensing characteristic corresponding to a morphology of the sensed cardiac signals sensed during a predetermined sensing window, and the second oversensing characteristic corresponding to RR-intervals associated with the sensed cardiac signals.

4. The method of claim 1 , wherein determining the adjusting characteristic comprises:

defining a plurality of sub-segments associated with the sensing window; and

determining the adjusting characteristic associated with the cardiac signals within each sub-segment of the plurality of sub-segments.

5. The method of claim 4 , wherein determining the adjusting characteristic comprises:

determining a sub-segment parameter for each of the plurality of sub-segments;

comparing the sub-segment parameter with a sub-segment parameter threshold; and

determining whether to update the sensing parameter in response to the comparing.

6. The method of claim 5 , further comprising:

determining a maximum amplitude and an absolute minimum amplitude associated with the sensing window; and

comparing the maximum amplitude and the absolute minimum amplitude, wherein the sub-segment parameter and the sub-segment parameter threshold are determined in response to the comparing of the maximum amplitude and the absolute minimum amplitude.

7. The method of claim 5 , further comprising:

determining a local parameter for each sub-segment of the plurality of sub-segments; and

comparing the local parameter with the sub-segment parameter.

8. The method of claim 7 , wherein the sensing parameter is updated in response to the sub-segment parameter and one or more local parameters determined for only a predetermined number of sub-segments of the plurality of sub-segments.

9. The method of claim 1 , further comprising:

defining a plurality of sub-segments associated with the sensing window;

determining intervals associated with each sub-segment of the plurality of sub-segments;

determining a rate associated with each sub-segment of the plurality of sub-segments in response to the determined intervals; and

adjusting the sensing parameter in response to the determined rate associated with each sub-segment of the plurality of sub-segments.

10. The method of claim 1 , further comprising:

defining a plurality of sub-segments associated with the sensing window;

determining intervals associated with one or more sub-segments of the plurality of sub-segments;

determining a rate associated with the one or more sub-segments of the plurality of sub-segments in response to the determined intervals;

determining the number of sub-segments of the plurality of sub-segments for which the sub-segment rate was determined; and

adjusting the sensing parameter in response to the determined rate associated with each of the determined number of sub-segments.

11. A method of determining oversensing in a medical device, comprising:

sensing cardiac signals;

determining a first oversensing characteristic and a second oversensing characteristic, the first oversensing characteristic corresponding to a morphology of the sensed cardiac signals sensed during a predetermined sensing window, and the second oversensing characteristic corresponding to RR-intervals associated with the sensed cardiac signals;

identifying oversensing in response to the first oversensing characteristic and the second oversensing characteristic;

defining a plurality of sub-segments associated with the sensed cardiac signals sensed during the sensing window;

determining a sensing window parameter associated with the sensing window and a sub-segment parameter associated with each of the plurality of sub-segments;

comparing the sub-segment parameter for each of the plurality of sub-segments to the sensing window parameter to determine sub-segments of the plurality of sub-segments having a first adjusting characteristic;

determining a local parameter for each sub-segment of the plurality of sub-segments having the first adjusting characteristic;

comparing the local parameter to a corresponding sub-segment parameter to determine sub-segments of the plurality of sub-segments having a second adjusting characteristic; and

updating a sensing parameter in response to the determined sub-segments of the plurality of sub-segments having a second adjusting characteristic.

12. The method of claim 11 , wherein the cardiac signals are sensed from a plurality of electrodes, the plurality of electrodes forming a first sensing vector and a second sensing vector, and further comprising:

determining a first spectral width corresponding to the cardiac signals sensed along the first sensing vector and a second spectral width corresponding to the cardiac signals sensed along the second sensing vector;

identifying one of the first spectral width and the second spectral width as a preferred spectral width; and

comparing the preferred spectral width to a spectral width threshold.

13. The method of claim 11 , wherein the cardiac signals are sensed from a plurality of electrodes, the plurality of electrodes forming a first sensing vector and a second sensing vector, and further comprising:

determining a first metric of signal energy content corresponding to the cardiac signals sensed along the first sensing vector and a second metric of signal energy content corresponding to the cardiac signals sensed along the second sensing vector;

identifying one of the first metric of signal energy content and the second metric of signal energy content as a preferred metric of signal energy content; and

comparing the preferred metric of signal energy content to a metric of signal energy content threshold.

14. The method of claim 11 , wherein the cardiac signals are sensed from a plurality of electrodes, the plurality of electrodes forming a first sensing vector and a second sensing vector, and further comprising:

determining a first heart rate metric difference corresponding to the cardiac signals sensed along the first sensing vector and a second heart rate metric difference corresponding to the cardiac signals sensed along the second sensing vector;

identifying one of the first heart rate metric difference and the second heart rate metric difference as a preferred heart rate metric difference; and

comparing the preferred heart rate metric difference to a heart rate metric difference threshold.

15. The method of claim 11 , wherein the cardiac signals are sensed from a plurality of electrodes, the plurality of electrodes forming a first sensing vector and a second sensing vector, and further comprising:

determining a first spectral width corresponding to the cardiac signals sensed along the first sensing vector and a second spectral width corresponding to the cardiac signals sensed along the second sensing vector;

identifying one of the first spectral width and the second spectral width as a preferred spectral width;

comparing the preferred spectral width to a spectral width threshold;

determining a first metric of signal energy content corresponding to the cardiac signals sensed along the first sensing vector and a second metric of signal energy content corresponding to the cardiac signals sensed along the second sensing vector;

identifying one of the first metric of signal energy content and the second metric of signal energy content as a preferred metric of signal energy content;

comparing the preferred metric of signal energy content to a metric of signal energy content threshold;

determining a first heart rate metric difference corresponding to the cardiac signals sensed along the first sensing vector and a second heart rate metric difference corresponding to the cardiac signals sensed along the second sensing vector;

identifying one of the first heart rate metric difference and the second heart rate metric difference as a preferred heart rate metric difference; and

comparing the preferred heart rate metric difference to a heart rate metric difference threshold, wherein oversensing is identified in response to the comparings.

16. The method of claim 11 , wherein the cardiac signals are sensed from a plurality of electrodes, the plurality of electrodes forming a first sensing vector and a second sensing vector, and further comprising:

determining whether the cardiac signals sensed along the first sensing vector are reliable;

determining whether the cardiac signals sensed along the second sensing vector are reliable;

determining, in response to one of the cardiac signals sensed along the first sensing vector and the cardiac signals sensed along the second sensing vector reliable being reliable, a spectral width corresponding to the one of the cardiac signals sensed along the first sensing vector and the cardiac signals sensed along the second sensing vector; and

comparing the spectral width to a spectral width threshold.

17. The method of claim 11 , wherein the cardiac signals are sensed from a plurality of electrodes, the plurality of electrodes forming a first sensing vector and a second sensing vector, and further comprising:

determining whether the cardiac signals sensed along the first sensing vector are reliable;

determining whether the cardiac signals sensed along the second sensing vector are reliable;

determining, in response to one of the cardiac signals sensed along the first sensing vector and the cardiac signals sensed along the second sensing vector reliable being reliable, a metric of signal energy content corresponding to the one of the cardiac signals sensed along the first sensing vector and the cardiac signals sensed along the second sensing vector; and

comparing the metric of signal energy content to a metric of signal energy content threshold.

18. The method of claim 11 , wherein the cardiac signals are sensed from a plurality of electrodes, the plurality of electrodes forming a first sensing vector and a second sensing vector, and further comprising:

determining whether the cardiac signals sensed along the first sensing vector are reliable;

determining whether the cardiac signals sensed along the second sensing vector are reliable;

determining, in response to one of the cardiac signals sensed along the first sensing vector and the cardiac signals sensed along the second sensing vector reliable being reliable, a heart rate metric difference corresponding to the one of the cardiac signals sensed along the first sensing vector and the cardiac signals sensed along the second sensing vector; and

comparing the heart rate metric difference to a heart rate metric difference threshold.

19. The method of claim 11 , wherein the cardiac signals are sensed from a plurality of electrodes, the plurality of electrodes forming a first sensing vector and a second sensing vector, and further comprising:

determining whether the cardiac signals sensed along the first sensing vector are reliable;

determining whether the cardiac signals sensed along the second sensing vector are reliable;

determining, in response to one of the cardiac signals sensed along the first sensing vector and the cardiac signals sensed along the second sensing vector reliable being reliable, a spectral width corresponding to the one of the cardiac signals sensed along the first sensing vector and the cardiac signals sensed along the second sensing vector;

comparing the spectral width to a spectral width threshold;

determining a metric of signal energy content corresponding to the one of the cardiac signals sensed along the first sensing vector and the cardiac signals sensed along the second sensing vector;

comparing the metric of signal energy content to a metric of signal energy content threshold;

determining a heart rate metric difference corresponding to the one of the cardiac signals sensed along the first sensing vector and the cardiac signals sensed along the second sensing vector; and

comparing the heart rate metric difference to a heart rate metric difference threshold, wherein oversensing is identified in response to the comparings.

20. The method of claim 11 , wherein the cardiac signals are sensed from a non-intravenous location.

21. A method of determining oversensing in a medical device, comprising:

sensing cardiac signals;

determining an oversensing characteristic associated with cardiac signals sensed during a predetermined sensing window;

identifying oversensing in response to the oversensing characteristic;

determining, in response to oversensing being identified, an adjusting characteristic associated with cardiac signals sensed during the predetermined sensing window, wherein determining the adjusting characteristic comprises defining a plurality of sub-segments associated with the sensing window and determining the adjusting characteristic associated with the cardiac signals within each sub-segment of the plurality of sub-segments; and

updating a sensing parameter in response to the determined adjusting characteristic.