Method and apparatus for detecting arrhythmias in a medical device

• US 7,769,452 B2
• Filed: 04/28/2006
• Issued: 08/03/2010
• Est. Priority Date: 03/29/2006
• 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
• Primary Examiner(s): Layno; Carl H
• Assistant Examiner(s): Behringer; Luther G
• Application Number:
  US11/380,807
• Publication Number:
  US 20070239044A1
• Time in Patent Office: 1,558 Days
• Field of Search: 600508-510, 600/512, 600/513, 600/515, 600/518, 600/521, 600/523, 607/5, 607/9, 607/18
• US Class Current: 607/18
• 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 of detecting a cardiac event in a medical device that includes sensing cardiac signals from a plurality of electrodes forming a first sensing vector and a second sensing vector, determining whether the first sensing vector and the second sensing vector is corrupted by noise, and determining, in response to one of the first sensing vector and the second sensing vector being corrupted by noise, whether the other of the first sensing vector and the second sensing vector is one of a first cardiac event and a second cardiac event different from the first cardiac event.

Claims

1. A method of treating a cardiac event of a heart of a patient by a medical device comprising therapeutic componentry and a plurality electrodes, comprising the steps of:

sensing cardiac signals from the plurality of electrodes, the plurality of electrodes forming a first sensing vector and a second sensing vector;

determining with the medical device whether each one of the first sensing vector and the second sensing vector is corrupted by noise;

if the first sensing vector is corrupted by noise and the second sensing vector is not corrupted by noise, determining with the medical device if a cardiac signal sensed by the second sensing vector is indicative of one of a first cardiac rhythm and a second cardiac rhythm different from the first cardiac rhythm;

then if the cardiac signal sensed by the second sensing vector is indicative of the first cardiac rhythm, the medical device delivering a first therapeutic output to the patient based, at least in part, on the cardiac signal sensed by the second sensing vector and a cardiac signal sensed by the first sensing vector both being indicative of a first cardiac event;

if the cardiac signal sensed by the second sensing vector is indicative of the second cardiac rhythm, the medical device delivering a second therapeutic output to the patient based, at least in part, on the cardiac signal sensed by second sensing vector being indicative of a second cardiac event different from the first cardiac event.

2. The method of claim 1, wherein the determining with the medical device whether the cardiac signal sensed by the second sensing vector is indicative of one of the first cardiac rhythm and the second cardiac rhythm step comprises:

determining whether RR-intervals associated with the cardiac signal sensed by the second sensing vector are regular; and

determining the second sensing vector is the first cardiac rhythm based, at least in part, on the RR-intervals not being regular.

3. The method of claim 2, wherein determining whether RR-intervals associated with the cardiac signal sensed by the second sensing vector are regular comprises:

determining a maximum RR-interval and a minimum RR-interval; and

determining whether an interval difference corresponding to the maximum RR-interval and the minimum RR-interval is greater than a stability threshold.

4. The method of claim 3, wherein the RR-intervals include twelve RR-intervals, the maximum RR-interval corresponding to the largest RR-interval of the twelve RR-intervals and the minimum RR-interval corresponding to the sixth largest RR-interval of the twelve RR-intervals.

5. The method of claim 1, wherein, in the if cardiac signal sensed by the second sensing vector is indicative of the first cardiac rhythm, the medical device delivering the first therapeutic output to the patient step, the therapeutic output is delivered to the patient based, at least in part, and the cardiac signal sensed by the second sensing vector being within a first event threshold.

6. The method of claim 5, wherein the cardiac signal sensed by the second sensing vector defines a plurality of rates of change and a range;

and

wherein the cardiac signal sensed by the second sensing vector is within the first event threshold is based, at least on in part, on a comparison of the plurality of rates of change and the range to the first event threshold.

7. The method of claim 6, wherein the cardiac signal sensed by the second sensing vector is within the first event threshold if:

a number of individual ones of the plurality rates of change of the cardiac signal sensed by the second sensing vector less than a rate of change threshold are not less than a first boundary, the rate of change threshold being based, at least in part, on the cardiac signal sensed by the second sensing vector; and

the range is less than a second boundary different from the first boundary.

8. The method of claim 5

wherein the cardiac signal sensed by the first sensing vector and the cardiac signal sensed by the second sensing vector are both indicative of the first cardiac event if both the cardiac signal sensed by the first sensing vector and to the cardiac signal sensed by the second sensing vector are within the first event threshold.

9. The method of claim 5, wherein the second sensing vector is within the first event threshold if the cardiac signal sensed by the second sensing vector corresponds, at least in part, to a first characteristic, a second characteristic and a third characteristic of the cardiac signal sensed by at least one of the first sensing vector and the second sensing vector over a predetermined sensing window.

10. The method of claim 9, wherein the cardiac signal sensed by the second sensing vector corresponds to the first characteristic, the second characteristic and the third characteristic if the first characteristic is less than a first boundary and the third characteristic is less than a second boundary, wherein:

the first boundary corresponds to the first characteristic and the second characteristic; and

the second boundary corresponds to the first characteristic and the third chracteristic.

11. The method of claim 1 wherein if the cardiac signal sensed by the second sensing vector is indicative of the first cardiac rhythm, the medical device delivers the first therapeutic output to the patient only based, at least in part, on the cardiac signal sensed by the second sensing vector and a cardiac signal sensed by the first sensing vector both being indicative of a first cardiac event;

and wherein if the cardiac signal sensed by the second sensing vector is indicative of the second cardiac rhythm, the medical device delivering the second therapeutic output to the patient only based, at least in part, on the cardiac signal sensed by second sensing vector being indicative of second cardiac event.

12. A method of treating a cardiac event with a medical device comprising therapeutic componentry and a plurality of electrodes, comprising the steps of:

sensing cardiac signals from the plurality of electrodes, the plurality of electrodes forming a first sensing vector and a second sensing vector;

determining with the medical device whether each one of the first sensing vector and the second sensing vector is corrupted by noise;

if the first sensing vector is corrupted by noise and the second sensing vector is not corrupted by noise, determining whether RR-intervals associated with the second sensing vector are regular;

determining the cardiac signal sensed by the second sensing vector is a first cardiac rhythm based, at least in part, on the RR-intervals not being regular;

if the cardiac signal sensed by the second sensing vector is indicative of the first cardiac rhythm, the medical device delivering a therapeutic output to the patient based, at least in part, on the cardiac signal sensed by the second sensing vector being within a first event threshold.

13. The method of claim 12, wherein the cardiac signal sensed by the second sensing vector defines a plurality of rates of change and a range;

and

wherein the cardiac signals sensed by the second sensing vector within the first event threshold is based, at least in part, on a comparison of the plurality of rates of change and the range to the first event threshold.

14. The method of claim 13, wherein the cardiac signal sensed by the second sensing vector is within the first event threshold if:

a number of individual ones of the plurality of rates of change of the cardiac signal sensed by the second sensing vector less than a rate of change threshold are not less than a first boundary, the rate of change threshold being based, at least in part, on the cardiac signal sensed by the second sensing vector; and

the range is less than a second boundary different from the first boundary.

15. The method of claim 12,

wherein the medical device delivers the therapeutic output to the patient further based, at least in part, on the cardiac signal sensed by the first sensing vector and the cardiac signal sensed by the second sensing vector both being within the first event threshold.

16. The method of claim 12, further comprising:

determining the cardiac signal sensed by the second sensing vector is a second cardiac rhythm based, at least in part, on the RR-intervals being regular; and

if the cardiac signals sensed by the second sensing vector are indicative of the second cardiac rhythm, the medical device delivering the therapeutic output to the patient based, at least in part, on the second sensing vector being within a second event threshold defined, at least in part, by a first characteristic, a second characteristic and a third characteristic of the cardiac signal sensed by the second sensing vector over a predetermined sensing window.

17. The method of claim 16, wherein the cardiac signal sensed by the second sensing vector corresponds to the first characteristic, the second characteristic and the third characteristic if the first characteristic is less than a first boundary and the third characteristic is less than a second boundary, wherein:

the first boundary corresponds to the first characteristic and the second characteristic; and

the second boundary corresponds to the first characteristic and the third characteristic.

18. A method of treating a cardiac event with a medical device comprising therapeutic componentry and a plurality of electrodes, comprising the steps of:

sensing cardiac signals from the plurality of electrodes, the plurality of electrodes forming a first sensing vector and a second sensing vector;

determining with the medical device whether each of the first sensing vector and the second sensing vector is corrupted by noise;

if the first sensing vector is corrupted by noise and the second sensing vector is not corrupted by noise, determining whether RR-intervals associated with the second sensing vector are regular;

determining the cardiac signal sensed by the second sensing vector is a first cardiac rhythm based, at least in part, on the RR-intervals not being regular and that the cardiac signal sensed by the second sensing vector is indicative of a second cardiac rhythm based, at least in part, on the RR-intervals being regular;

if the cardiac signal sensed by the second sensing vector is indicative of the first cardiac rhythm, the medical device delivering a first therapeutic output to the patient based, at least in part, on the cardiac signal sensed by the second sensing vector being within a first event threshold;

if the cardiac signal sensed by the second sensing vector is indicative of the second cardiac rhythm, the medical device delivering a second therapeutic output to the patient based, at least in part, on the cardiac signal sensed by the second sensing vector being within a second event threshold different from the first event threshold.

19. The method of claim 18, wherein the cardiac signal sensed by the second sensing vector defines a plurality of rates of change and a rage;

and

wherein the cardiac signal sensed by the second sensing vector is within the first event threshold is based, at least in part, on a comparison of the plurality of rates of change and the range to the first event threshold.

20. The method of claim 19, wherein the medical device delivers the second therapeutic output to the patient if the cardiac signal sensed by the second sensing vector is indicative of the second cardiac rhythm and further based, at least on the second sensing vector being within a second event threshold defined, at least in part, by on a first characteristic, a second characteristic and a third characteristic of the cardiac signal sensed by the second sensing vector over a predetermined sensing window.

21. The method of claim 20, wherein the cardiac signal sensed by the second sensing vector is within the first event threshold if:

a number of individual ones of the plurality rates of change of the cardiac signal sensed by the second sensing vector less than a rate of change threshold are not less than a first boundary, the rate of change threshold being based, at least in part, on the cardiac signal sensed by the second sensing vector; and

the range is less than a second boundary different from the first boundary.

22. The method of claim 21, wherein the cardiac signal sensed by the second sensing corresponds to the first characteristic, the second characteristic and the third characteristic if the first characteristic is less than a third boundary and the third characteristic is less than a fourth boundary, wherein:

the third boundary corresponding to the first characteristic and the second characteristic; and

the fourth boundary corresponding to the first characteristic and the third characteristic.