METHOD AND APPARATUS FOR SELECTING A SENSING VECTOR CONFIGURATION IN A MEDICAL DEVICE

• US 20150305638A1
• Filed: 07/24/2014
• Published: 10/29/2015
• Est. Priority Date: 04/24/2014
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Zhang, Xusheng
• Granted Patent: US 10,244,957 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/25 Bioelectric electrodes therefor
• CPC Class Codes: A61B 5/341 Vectorcardiography [VCG]
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

A method and medical device for determining sensing vectors that includes sensing cardiac signals from a plurality of electrodes, the plurality of electrodes forming a plurality of sensing vectors, determining a sensing vector metric in response to the sensed cardiac signals, determining a morphology metric associated with a morphology of the sensed cardiac signals, determining vector selection metrics in response to the determined sensing vector metric and the determined morphology setting, and selecting a sensing vector of the plurality of sensing vectors in response to the determined vector selection metrics.

Claims

1. A method of determining sensing vectors in a medical device, comprising:

sensing cardiac signals from a plurality of electrodes, the plurality of electrodes forming a plurality of sensing vectors;

determining a sensing vector metric in response to the sensed cardiac signals;

determining a morphology metric associated with a morphology of the sensed cardiac signals;

determining vector selection metrics in response to the determined sensing vector metric and the determined morphology setting; and

selecting a sensing vector of the plurality of sensing vectors in response to the determined vector selection metrics.

2. The method of claim 1, wherein determining a sensing vector metric comprises;

sensing an R-wave in response to the cardiac signal exceeding a sensing threshold;

determining signal differences between the sensed cardiac signal and the sensing threshold in response to the sensed R-wave; and

setting the sensing vector metric in response to the determined signal differences.

3. The method of claim 2, wherein selecting a sensing vector comprises:

selecting a vector of the plurality of vectors having the lowest determined signal difference as a first sensing vector; and

selecting a vector of the plurality of vectors having the next lowest determined signal difference as a second sensing vector.

4. The method of claim 1, wherein determining a morphology metric comprises:

sensing an R-wave in response to the cardiac signal exceeding a sensing threshold;

determining pulses associated with the sensed R-wave;

determining a number of the determined pulses that are less than a narrow pulse threshold; and

setting the morphology metric equal to the determined number of pulses.

5. The method of claim 4, wherein determining a number of the determined pulses that are less than a narrow pulse threshold comprises:

determining, for each pulse, whether a width of the pulse is less than a narrow pulse width threshold;

determining, for each pulse, whether a pulse amplitude is greater than a pulse amplitude threshold; and

determining a number of the determined pulses that are both less than the narrow pulse threshold and greater than the pulse amplitude threshold.

6. The method of claim 1, further comprising:

ranking vectors of the plurality of sensing vectors in response to the determined sensing vector metric to determine a first vector ranking;

ranking vectors of the plurality of sensing vectors in response to the determined morphology metric to determine a second vector ranking;

comparing the first vector ranking and the second vector ranking; and

updating the first vector ranking in response to the comparing.

7. The method of claim 6, wherein the first vector ranking comprises a first sensing vector, a second sensing vector and a third sensing vector and the second vector ranking comprises a low morphology metric associated with a low number of pulses, a medium morphology metric and a high morphology metric, and wherein comparing the first vector ranking and the second vector ranking comprises determining whether the second vector ranking of one of the first sensing vector and the second sensing vector corresponds to the high morphology metric.

8. The method of claim 7, wherein updating the first vector ranking comprises:

selecting the first sensing vector and the second sensing vector in response to the second vector ranking of one of the first sensing vector and the second sensing vector not being determined to correspond to the high morphology metric; and

determining whether to select the third sensing vector in response to the second vector ranking of one of the first sensing vector and the second sensing vector being determined to correspond to the high morphology metric.

9. The method of claim 8, wherein determining whether to select the third sensing vector comprises:

comparing the morphology metric of the one of the first sensing vector and the second sensing vector determined to correspond to the high morphology metric and the morphology metric of the third sensing vector to determine a first relative difference;

comparing the vector selection of the one of the first sensing vector and the second sensing vector determined to correspond to the high morphology metric and the morphology metric of the third sensing vector to determine a second relative difference; and

selecting the third sensing vector in response to the first relative difference and the second relative difference.

10. The method of claim 9, further comprising:

determining whether the first relative difference is greater than a first difference threshold;

determining whether the second relative difference is less than a second difference threshold; and

updating the selected sensing vectors from the first sensing vector and the second sensing vector to the one of the first sensing vector and the second sensing vector not determined to correspond to the high morphology metric and the third sensing vector in response to both the first relative difference being greater than the first difference threshold and the second relative difference being less than the second difference threshold.

11. A medical device, comprising:

a plurality of electrodes capable of forming a plurality of sensing vectors for sensing cardiac signals; and

a processor configured to determine a sensing vector metric in response to the sensed cardiac signals, determine a morphology metric associated with a morphology of the sensed cardiac signals, determine vector selection metrics in response to the determined sensing vector metric and the determined morphology setting, and select a sensing vector of the plurality of sensing vectors in response to the determined vector selection metrics.

12. The medical device of claim 11, wherein the processor is further configured to sense an R-wave in response to the cardiac signal exceeding a sensing threshold, determine signal differences between the sensed cardiac signal and the sensing threshold in response to the sensed R-wave, and set the sensing vector metric in response to the determined signal differences.

13. The medical device of claim 12, wherein the processor is further configured to select a vector of the plurality of vectors having the lowest determined signal difference as a first sensing vector, and select a vector of the plurality of vectors having the next lowest determined signal difference as a second sensing vector.

14. The medical device of claim 11, wherein the processor is further configured to sense an R-wave in response to the cardiac signal exceeding a sensing threshold, determine pulses associated with the sensed R-wave, determine a number of the determined pulses that are less than a narrow pulse threshold, and set the morphology metric equal to the determined number of pulses.

15. The medical device of claim 14, wherein the processor is further configured to determine, for each pulse, whether a width of the pulse is less than a narrow pulse width threshold, determine, for each pulse, whether a pulse amplitude is greater than a pulse amplitude threshold, and determine a number of the determined pulses that are both less than the narrow pulse threshold and greater than the pulse amplitude threshold.

16. The medical device of claim 11, wherein the processor is further configured to rank vectors of the plurality of sensing vectors in response to the determined sensing vector metric to determine a first vector ranking, rank vectors of the plurality of sensing vectors in response to the determined morphology metric to determine a second vector ranking, compare the first vector ranking and the second vector ranking, and update the first vector ranking in response to the comparing.

17. The medical device of claim 16, wherein the first vector ranking comprises a first sensing vector, a second sensing vector and a third sensing vector and the second vector ranking comprises a low morphology metric associated with a low number of pulses, a medium morphology metric and a high morphology metric, and wherein the processor is further configured to determine whether the second vector ranking of one of the first sensing vector and the second sensing vector corresponds to the high morphology metric.

18. The medical device of claim 17, wherein the processor is further configured to select the first sensing vector and the second sensing vector in response to the second vector ranking of one of the first sensing vector and the second sensing vector not being determined to correspond to the high morphology metric, and determine whether to select the third sensing vector in response to the second vector ranking of one of the first sensing vector and the second sensing vector being determined to correspond to the high morphology metric.

19. The medical device of claim 18, wherein the processor is further configured to compare the morphology metric of the one of the first sensing vector and the second sensing vector determined to correspond to the high morphology metric and the morphology metric of the third sensing vector to determine a first relative difference, compare the vector selection of the one of the first sensing vector and the second sensing vector determined to correspond to the high morphology metric and the morphology metric of the third sensing vector to determine a second relative difference, and select the third sensing vector in response to the first relative difference and the second relative difference.

20. The medical device of claim 19, wherein the processor is further configured to determine whether the first relative difference is greater than a first difference threshold, determine whether the second relative difference is less than a second difference threshold;

and update the selected sensing vectors from the first sensing vector and the second sensing vector to the one of the first sensing vector and the second sensing vector not determined to correspond to the high morphology metric and the third sensing vector in response to both the first relative difference being greater than the first difference threshold and the second relative difference being less than the second difference threshold.

21. A non-transitory, computer-readable storage medium storing instructions for causing a processor included in a medical device to perform a method for determining sensing vectors, the method comprising:

sensing cardiac signals from a plurality of electrodes, the plurality of electrodes forming a plurality of sensing vectors;

determining a sensing vector metric in response to the sensed cardiac signals;

determining a morphology metric associated with a morphology of the sensed cardiac signals;

determining vector selection metrics in response to the determined sensing vector metric and the determined morphology setting; and

selecting a sensing vector of the plurality of sensing vectors in response to the determined vector selection metrics.