Method and apparatus for detecting arrhythmias in a medical device

• US 8,095,206 B2
• Filed: 05/01/2007
• Issued: 01/10/2012
• Est. Priority Date: 05/01/2007
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Ghanem, Raja N., Stadler, Robert W., Zhang, Xusheng, Kleckner, Karen J., Krause, Paul G.
• Primary Examiner(s): Layno, Carl H
• Assistant Examiner(s): SARCIONE, JESSICA LYNN
• Application Number:
  US11/742,618
• Publication Number:
  US 20080275519A1
• Time in Patent Office: 1,715 Days
• Field of Search: 600508-510, 600515-519, 600/521, 607/9, 607/14, 607 25- 27
• US Class Current: 600/509
• 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 adjusting a sensing parameter in a medical device that includes a sensing electrode sensing cardiac signals, a processor to determine an adjusting characteristic associated with the cardiac signals sensed over a predetermined sensing window, and a control unit to update the sensing parameter in response to the determined adjusting characteristic.

Claims

1. An apparatus for adjusting a sensing parameter in a medical device, comprising:

a sensing electrode sensing cardiac signals;

a processor to;

define a plurality of sub-segments associated with a predetermined sensing window;

determine an adjusting characteristic associated with the cardiac signals sensed within each sub-segment of the plurality of sub-segments and over the predetermined sensing window;

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

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

a control unit to determine whether to update the sensing parameter in response to the comparing and update the sensing parameter in response to the determined adjusting characteristic and the determination to update the sensing parameter.

2. The apparatus of claim 1, wherein the cardiac signals are sensed non-transvenously.

3. The apparatus of claim 1, wherein the processor determines a sensing window parameter associated with the sensing window, and sets the sub-segment parameter threshold equal to the determined sensing window parameter.

4. The apparatus of claim 1, wherein the processor determines a maximum amplitude and an absolute minimum amplitude associated with the sensing window, compares the maximum amplitude and the absolute minimum amplitude, and determines the sub-segment parameter and the sub-segment parameter threshold in response to the comparing of the maximum amplitude and the absolute minimum amplitude.

5. The apparatus of claim 1, wherein the processor determines a local parameter for each sub-segment of the plurality of sub-segments, and compares the local parameter with the sub-segment parameter.

6. The apparatus of claim 5, wherein the control unit updates the sensing parameter 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.

7. The apparatus of claim 1, wherein the processor determines intervals associated with each sub-segment of the plurality of sub-segments, and determines a rate associated with each sub-segment of the plurality of sub-segments in response to the determined intervals, and wherein the control unit adjusts the sensing parameter in response to the determined rate associated with each sub-segment of the plurality of sub-segments.

8. The apparatus of claim 1, wherein the processor:

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

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

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

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

9. A method of updating a sensing parameter in a medical device, comprising:

sensing cardiac signals;

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

determining an adjusting characteristic associated with the cardiac signals sensed within each sub-segment of the plurality of sub-segments and over the predetermined sensing window;

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

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

determining whether to update the sensing parameter in response to the comparing; and

updating the sensing parameter in response to the determined adjusting characteristic and the determination to update the sensing parameter.

10. The method of claim 9, wherein the cardiac signals are sensed non-transvenously.

11. The method of claim 9, further comprising determining a sensing window parameter associated with the sensing window, wherein the sub-segment parameter threshold is equal to the determined sensing window parameter.

12. The method of claim 9, 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.

13. The method of claim 9, 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.

14. The method of claim 13, 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.

15. The method of claim 9, further comprising:

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.

16. The method of claim 15, further comprising:

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 in 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.

17. The method of claim 9, wherein the sensing window is approximately equal to three seconds and each of the plurality of sub-segments are approximately equal to 750 ms.

18. A method of updating a sensing parameter in a medical device, comprising:

sensing cardiac signals;

defining a plurality of sub-segments associated with the sensed cardiac signals sensed during a 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.

19. The method of claim 18, wherein the cardiac signals are sensed non-transvenously.

20. The method of claim 19, 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 sensing window parameter are determined in response to the comparing of the maximum amplitude and the absolute minimum amplitude.