Method and apparatus for detecting arrhythmias in a subcutaneous medical device

• US 9,174,062 B2
• Filed: 03/16/2007
• Issued: 11/03/2015
• Est. Priority Date: 03/29/2006
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Stadler, Robert W., Ghanem, Raja N., Zhang, Xusheng
• Primary Examiner(s): LEVICKY, WILLIAM J
• Application Number:
  US11/687,094
• Publication Number:
  US 20070232948A1
• Time in Patent Office: 3,154 Days
• Field of Search: 607/4, 607/5, 607/14, 600/515, 600/571, 600/518
• US Class Current: 1/1
• CPC Class Codes: A61B 5/287 Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61B 5/341 Vectorcardiography [VCG]
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/361 Detecting fibrillation
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/364 Detecting abnormal ECG interval, e.g. extrasystoles, ectopic heartbeats
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate
• CPC Class Codes: A61N 1/3925 Monitoring; Protecting
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion
• CPC Class Codes: A61N 1/3987 characterised by the timing or triggering of the shock
• CPC Class Codes: Y10S 128/901 Suppression of noise in electric signal
• CPC Class Codes: Y10S 128/902 Biological signal amplifier

Abstract

A method and apparatus for detecting a cardiac event in a medical device that includes sensing cardiac signals from a plurality of electrodes, determining a relationship between a plurality of characteristics associated with a morphology of the cardiac signals sensed during a predetermined sensing window, generating a threshold in response to the determined relationship, comparing a first characteristic of the plurality of characteristics with the threshold, and determining whether the sensed cardiac signals are associated with the cardiac event in response to the comparing of the first characteristic.

Claims

1. A method of detecting a cardiac event with a medical device comprising a processor and a plurality of electrodes, comprising the steps of:

sensing cardiac signals from the plurality of electrodes during a predetermined sensing window;

determining a relationship between a plurality of characteristics associated with a morphology of the cardiac signals;

generating a threshold in response to the relationship between the plurality of characteristics associated with the morphology of the cardiac signals;

comparing a first characteristic of the plurality of characteristics with the threshold to obtain a comparison indicative of an association of the cardiac signals with the cardiac event; and

delivering a therapeutic output based, at least in part, on the comparison indicative of an association of the cardiac signals with the cardiac event.

2. The method of claim 1, wherein the plurality of characteristics include an amplitude of the sensed cardiac signals and a range of the sensed cardiac signals.

3. The method of claim 2, wherein the first characteristic corresponds to the amplitude.

4. The method of claim 3, wherein the amplitude corresponds to a normalized mean rectified amplitude and the range corresponds to a spectral width.

5. The method of claim 4, wherein the threshold corresponds to the normalized rectified mean amplitude being equal to 0.2×

spectral width +3.

6. The method of claim 1, wherein the predetermined sensing window is between approximately 0.5 and 10 seconds.

7. The method of claim 1, wherein the plurality of electrodes are positioned non-transvenously.

8. A method of detecting a cardiac event with a medical device comprising a processor and a plurality of electrodes forming a first sensing vector and a second sensing vector different from the first sensing vector, comprising:

sensing cardiac signals from the plurality of electrodes during a predetermined sensing window;

determining a first relationship between a first plurality of characteristics associated with cardiac signals sensed along the first sensing vector and a second relationship between a second plurality of characteristics along the second sensing vector during the predetermined sensing window;

generating a threshold in response to the first relationship between the first plurality of characteristics and the second relationship between the second plurality of characteristics;

comparing an individual one of the first plurality of characteristics with the threshold to obtain a first comparison indicative of an association of the cardiac signals sensed along the first sensing vector with the cardiac event;

comparing an individual one of the second plurality of characteristics with the threshold to obtain a second comparison indicative of an association of the cardiac signals sensed along the second sensing vector with the cardiac event; and

delivering a therapeutic output based, at least in part, on the first comparison indicative of an association of the cardiac signals sensed along the first sensing vector with the cardiac event and the second comparison indicative of an association of the cardiac signals sensed along the second sensing vector with the cardiac event.

9. The method of claim 8, wherein the plurality of characteristics include an amplitude of the sensed cardiac signals and a range of the sensed cardiac signals.

10. The method of claim 9, wherein the characteristic corresponds to the amplitude.

11. The method of claim 10, wherein the amplitude corresponds to a normalized mean rectified amplitude and the range corresponds to a spectral width.

12. The method of claim 11, wherein the threshold corresponds to the normalized rectified mean amplitude being equal to 0.2×

spectral width +3.

13. The method of claim 12, wherein the predetermined sensing window is between approximately 0.5 and 10 seconds.

14. The method of claim 8, wherein the plurality of electrodes are positioned non-transvenously.

15. A medical device for delivering a therapeutic output to a patient having a heart generating cardiac signals, comprising:

a plurality of electrodes;

a sensor operatively coupled to the plurality of electrodes and configured to sense the cardiac signals from the plurality of electrodes during a predetermined sensing window;

a processor, operatively coupled to the sensor and configured to;

determine a relationship between a plurality of characteristics associated with a morphology of the cardiac signals;

generate a threshold in response to the relationship between a plurality of characteristics associated with a morphology of the cardiac signals; and

compare a first characteristic of the plurality of characteristics with the threshold to obtain a comparison indicative of an association of the cardiac signals with the cardiac event; and

a therapy module, operatively coupled to the processor and the plurality of electrodes, configured to deliver a therapeutic output based, at least in part, on the comparison indicative of an association of the cardiac signals with the cardiac event.

16. The device of claim 15, wherein the plurality of characteristics include an amplitude of the sensed cardiac signals and a range of the sensed cardiac signals.

17. The device of claim 16, wherein the first characteristic corresponds to the amplitude.

18. The device of claim 17, wherein the amplitude corresponds to a normalized mean rectified amplitude and the range corresponds to a spectral width.

19. The device of claim 18, wherein the threshold corresponds to the normalized rectified mean amplitude being equal to 0.2×

spectral width +3.

20. The device of claim 19, wherein the predetermined sensing window is between approximately 0.5 and 10 seconds.

21. The device of claim 15, wherein the plurality of electrodes are positioned non-transvenously.