METHOD AND APPARATUS FOR DETECTING ARRHYTHMIAS IN A MEDICAL DEVICE

• US 20080275517A1
• Filed: 05/01/2007
• Published: 11/06/2008
• Est. Priority Date: 05/01/2007
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Kleckner, Karen J., Krause, Paul G., Ghanem, Raja N., Stadler, Robert W., Zhang, Xusheng
• Granted Patent: US 7,937,135 B2
• Time in Patent Office: Days
• US Class Current: 607/9
• CPC Class Codes: A61N 1/3704 Circuits specially adapted therefor, e.g. for sensitivity control
• CPC Class Codes: A61N 1/3925 Monitoring; Protecting

Abstract

A method and apparatus for determining oversensing in a medical device that includes 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, and updating a sensing parameter in response to the determined adjusting characteristic.

Claims

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;

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.

6. The method of claim 4, 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 4, 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 only in response to the sub-segment parameter and one or more local parameters being determined for 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 9, further comprising determining the number of sub-segments of the plurality of sub-segments for which the sub-segment rate was determined, wherein the adjusting of the sensing parameter corresponds to the determined number of sub-segments.

5. The method of 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.

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 the 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.