METHOD AND APPARATUS FOR SUBCUTANEOUS ECG VECTOR ACCEPTABILITY AND SELECTION

• US 20080269813A1
• Filed: 04/27/2007
• Published: 10/30/2008
• Est. Priority Date: 04/27/2007
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Greenhut, Saul E., Kleckner, Karen J., Stadler, Robert W.
• Granted Patent: US 7,904,153 B2
• Time in Patent Office: Days
• US Class Current: 607/5
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/364 Detecting abnormal ECG interval, e.g. extrasystoles, ectopic heartbeats
• 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: A61N 1/0504 Subcutaneous electrodes
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• 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

Abstract

An implantable medical device system and associated method select subcutaneous sensing electrodes for use in monitoring the heart rhythm. A subset of multiple sensing vectors is selected from a number of electrodes positioned at a first subcutaneous location and one electrode positioned at a second subcutaneous location. The subset of sensing vectors includes one vector that includes the electrode positioned at the second location. A signal quality parameter corresponding to each of the sensing vectors of the subset is determined.

Claims

1. An implantable medical device system, comprising:

a plurality of electrodes positioned at a first subcutaneous location;

at least one electrode positioned at a second subcutaneous location, wherein the plurality of electrodes at the first location and the electrode at the second location form multiple sensing vectors;

a sensing module for receiving ECG signals from the multiple sensing vectors; and

a control module configured to select a subset of the multiple sensing vectors, determine a signal quality parameter corresponding to each of the sensing vectors of the subset, determine whether each of the sensing vectors of the subset is acceptable in response to the determined signal quality parameter, and select at least one sensing vector for heart rhythm monitoring from the multiple sensing vectors in response to at least one of the subset sensing vectors being acceptable;

wherein the subset of sensing vectors includes only one vector that includes the electrode positioned at the second location.

2. The system of claim 1 wherein determining the signal quality parameter includes determining an R-wave peak amplitude.

3. The system of claim 1 wherein determining the signal quality parameter includes determining a low slope content.

4. The system of claim 1 wherein determining whether each of the sensing vectors of the subset is acceptable includes comparing a first signal quality parameter value to a first threshold, the first threshold being a tiered threshold.

5. The system of claim 4 wherein determining whether each of the sensing vectors of the subset is acceptable further includes comparing a second signal quality parameter value to a second threshold, the second threshold being defined as a function of the tiered first threshold.

6. The system of claim 4 wherein the first threshold is defined for a first vector of the subset, the first signal quality parameter value being measured for the first vector, and further comprising comparing a second signal quality parameter value to a second threshold, the second signal quality parameter value being measured for a second vector of the subset, the second threshold being defined for the second vector of the subset as a function of the tiered first threshold.

7. The system of claim 1 wherein determining whether each of the sensing vectors of the subset is acceptable comprises:

computing an acceptability index as a weighted function of a first signal quality parameter and a second signal quality parameter; and

comparing the acceptability index to a threshold.

8. The system of claim 1 wherein a first of the selected two sensing vectors is a vector including the electrode positioned at the second location and one of the plurality of electrodes positioned at the first location in response to the only one vector of the subset that includes the electrode positioned at the second location being acceptable.

9. The system of claim 8 wherein a second of the selected two sensing vectors includes two electrodes selected from the plurality of electrodes at the first location that are different electrodes than the one of the plurality of electrodes included in the first selected sensing vector.

10. The system of claim 8 wherein the first selected sensing vector is the only one vector of the subset that includes the electrode positioned at the second location in response to only two of the subset sensing vectors being acceptable.

11. The system of claim 1 wherein the first location corresponds to an anterior location.

12. The system of claim 1 wherein the second location corresponds to a posterior location.

13. The system of claim 1 further comprising a housing enclosing the sensing module and the control module, wherein the plurality of electrodes are positioned along the housing.

14. A method of an implantable medical device system, comprising:

selecting a subset of multiple sensing vectors available from a plurality of electrodes positioned at a first subcutaneous location and an electrode positioned at a second subcutaneous location wherein the subset of sensing vectors includes only one vector that includes the electrode positioned at the second location;

determining a signal quality parameter corresponding to each of the sensing vectors of the subset,

determining whether each of the sensing vectors of the subset is acceptable in response to the determined signal quality parameter, and

selecting two sensing vectors for heart rhythm monitoring from the multiple sensing vectors in response to at least two of the subset sensing vectors being acceptable.

15. The method of claim 14 wherein determining the signal quality parameter includes determining an R-wave peak amplitude.

16. The method of claim 14 wherein determining the signal quality parameter includes determining a low slope content.

17. The method of claim 14 wherein determining whether each of the sensing vectors of the subset is acceptable comprises comparing a first signal quality parameter to a first threshold, the first threshold being a tiered threshold.

18. The method of claim 17 wherein determining whether each of the sensing vectors of the subset is acceptable further comprises comparing a second signal quality parameter to a second threshold, the second threshold being defined as a function of the tiered first threshold.

19. The method of claim 17 wherein the first threshold is defined for a first vector of the subset, the first signal quality parameter value being measured for the first vector, and further comprising comparing a second signal quality parameter value to a second threshold, the second signal quality parameter value being measured for a second vector of the subset, the second threshold being defined for the second vector of the subset as a function of the tiered first threshold.

20. The method of claim 14 wherein determining whether each of the sensing vectors of the subset is acceptable comprises:

computing an acceptability index as a weighted function of a first signal quality parameter and a second signal quality parameter; and

comparing the acceptability index to a threshold.

21. The method of claim 14 wherein selecting two sensing vectors for heart rhythm monitoring comprises selecting a first sensing vector including the electrode positioned at the second location and one of the plurality of electrodes positioned at the first location in response to the only one vector of the subset that includes the electrode positioned at the second location being acceptable.

22. The method of claim 21 wherein selecting two sensing vectors for heart rhythm monitoring comprises selecting a second sensing vector including two electrodes selected from the plurality of electrodes at the first location that are different electrodes than the one of the plurality of electrodes included in the first sensing vector.

23. The method of claim 21 wherein the first selected sensing vector is the only one vector of the subset that includes the electrode positioned at the second location in response to only two of the subset sensing vectors being acceptable.

24. The method of claim 14 wherein the first location corresponds to an anterior location.

25. The method of claim 14 wherein the second location corresponds to a posterior location.

26. The method of claim 14 wherein the plurality of electrodes is positioned along an implantable medical device housing.

27. A computer readable medium having computer-executable instructions for performing a method comprising:

selecting a subset of multiple sensing vectors available from a plurality of electrodes positioned at a first subcutaneous location and one electrode positioned at a second subcutaneous location wherein the subset of sensing vectors includes only one vector that includes the electrode positioned at the second location;

determining a signal quality parameter corresponding to each of the sensing vectors of the subset,

determining whether each of the sensing vectors of the subset is acceptable in response to the determined signal quality parameter, and

selecting two sensing vectors for heart rhythm monitoring from the multiple sensing vectors in response to at least two of the subset sensing vectors being acceptable.