Method and apparatus for beat acquisition during template generation in a medical device having dual sensing vectors

• US 9,561,005 B2
• Filed: 01/21/2016
• Issued: 02/07/2017
• Est. Priority Date: 01/23/2015
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Zhang, Xusheng
• Primary Examiner(s): MANUEL, GEORGE C
• Application Number:
  US15/002,521
• Publication Number:
  US 20160213311A1
• Time in Patent Office: 383 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/287 Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61B 5/35 by template matching
• CPC Class Codes: A61B 5/361 Detecting fibrillation
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• 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 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61N 1/046 Specially adapted for shock therapy, e.g. defibrillation
• CPC Class Codes: A61N 1/0563 specially adapted for defibrillation or cardioversion
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

Techniques are described for generating beat templates and utilizing those beat templates to detect a cardiac event, e.g., a tachyarrhythmia. In particular, example methods and devices for acquiring qualified beats for template generation are described. Additionally, techniques are described for selecting subsets of the qualified beats to actually use in generating a beat template.

Claims

1. A method of acquiring qualified beats for template generation in a cardiac medical device comprising:

obtaining a first cardiac signal on a first sensing vector formed via a first subset of a plurality of extravascular electrodes;

obtaining a second cardiac signal on a second sensing vector formed via a second subset of the plurality of extravascular electrodes having at least one electrode different than the first subset, wherein the second cardiac signal is obtained concurrently with the first cardiac signal;

identifying beats within the first cardiac signal and the second cardiac signal;

applying beat qualification criteria to the beats within the first cardiac signal and the second cardiac signal to determine whether each of the beats is a qualified beat; and

generating a beat template based on at least a portion of the beats determined to be qualified beats.

2. The method of claim 1, wherein applying the beat qualification criteria comprises:

estimating a heart rate; and

determining the beats are not qualified beats for generating the beat template when the estimated heart rate is greater than or equal to a threshold heart rate at the time the beats were sensed.

3. The method of claim 2, wherein the threshold heart rate is at least one of a ventricular tachycardia threshold heart rate and a ventricular fibrillation threshold heart rate.

4. The method of claim 2, wherein applying the beat qualification criteria further comprises:

selecting a first identified beat of the first cardiac signal;

selecting a second identified beat of the second cardiac signal closest in time to the first identified beat;

determining an amount of time between the first identified beat in the first cardiac signal and the second identified beat in second cardiac signal;

determining the first identified beat and the second identified beat are not qualified beats for generating the beat template when the determined amount of time between the first identified beat and the second identified beat is greater than or equal to a threshold amount of time.

5. The method of claim 4, wherein applying the beat qualification criteria further comprises:

determining an interval between the first identified beat and an immediately preceding beat of the first cardiac signal; and

determining the first identified beat is not a qualified beat for generating the beat template when the interval is less than a threshold interval.

6. The method of claim 5, wherein applying the beat qualification criteria comprises determining the first identified beat is a qualified beat for generating the beat template when the estimated heart rate is less than the threshold heart rate, the determined amount of time between the first identified beat and the second identified beat is less than the threshold amount of time, and the interval is greater than or equal to the threshold interval.

7. The method of claim 5, wherein applying the beat qualification criteria further comprises:

determining an amplitude of the first identified beat; and

determining the first identified beat is a not a qualified beat for generating the beat template when the amplitude is less than an amplitude threshold.

8. The method of claim 7, wherein applying the beat qualification criteria comprises determining the first identified beat is a qualified beat for generating the template when the estimated heart rate is less than the threshold heart rate, the determined amount of time between the first identified beat and the second identified beat is less than the threshold amount of time, the interval is greater than or equal to the threshold interval, and the amplitude is greater than or equal to the amplitude threshold.

9. The method of claim 7, wherein applying the beat qualification criteria further comprises:

determining whether the first cardiac signal surrounding the first identified beat is noisy; and

determining the first identified beat is not a qualified beat for generating the beat template when the first cardiac signal surrounding the first identified beat is determined to be noisy.

10. The method of claim 9, wherein applying the beat qualification criteria comprises determining the first identified beat is a qualified beat for generating the beat template when the estimated heart rate is less than the threshold heart rate, the determined amount of time between the first identified beat and the second identified beat is less than the threshold amount of time, the interval is greater than or equal to the threshold interval, the amplitude is greater than or equal to the amplitude threshold, and the first cardiac signal surrounding the first identified beat is determined to not be noisy.

11. The method of claim 5, wherein applying the beat qualification criteria further comprises:

determining whether the first cardiac signal surrounding the first identified beat is noisy;

determining the first identified beat is not a qualified beat for generating the beat template when the first cardiac signal surrounding the first identified beat is determined to be noisy; and

determining the first identified beat is a qualified beat for generating the beat template when the estimated heart rate is less than the threshold heart rate, the determined amount of time between the first identified beat and the second identified beat is less than the threshold amount of time, the interval is greater than or equal to the threshold interval, and the first cardiac signal surrounding the first identified beat is determined to not be noisy.

12. The method of claim 1, further comprising:

detecting a tachycardia based at least on a comparison of beats to the generated beat template; and

providing an anti-tachycardia therapy in response to detecting the tachycardia.

13. An extravascular implantable cardioverter-defibrillator (ICD) system comprising:

an implantable electrical stimulation lead including a plurality of electrodes configured to sense cardiac electrical signals from an extravascular location within a patient;

an ICD coupled to the implantable electrical stimulation lead, the ICD comprising;

a housing that is formed at least partially of a conductive material to serve as a housing electrode;

sensing circuitry located within the housing and configured to obtain a first cardiac signal from a first electrode vector formed via any combination of the plurality of electrodes of the electrical stimulation lead and the housing electrode and obtain a second cardiac signal on a second electrode vector formed via any combination of the plurality of electrodes of the electrical stimulation lead and the housing electrode, the second electrode vector having at least one electrode different than the first electrode vector, wherein the second cardiac signal is obtained concurrently with the first cardiac signal;

a processor configured to identify beats within the first cardiac signal and the second cardiac signal, apply beat qualification criteria to the beats within the first cardiac signal and the second cardiac signal to determine whether each of the beats is a qualified beat, and generate a beat template based on at least a portion of the beats determined to be qualified beats.

14. The extravascular ICD of claim 13, wherein the processor is configured to estimate a heart rate and determine the beats are not qualified beats for generating the beat template when the estimated heart rate is greater than or equal to a threshold heart rate at the time the beats were sensed.

15. The extravascular ICD of claim 14, wherein the threshold heart rate is at least one of a ventricular tachycardia threshold heart rate and a ventricular fibrillation threshold heart rate.

16. The extravascular ICD of claim 14, wherein the processor is configured to select a first identified beat of the first cardiac signal, select a second identified beat of the second cardiac signal closest in time to the first identified beat, determine an amount of time between the first identified beat in the first cardiac signal and the second identified beat in second cardiac signal, and determine the first identified beat and the second identified beat are not qualified beats for generating the beat template when the determined amount of time between the first identified beat and the second identified beat is greater than or equal to a threshold amount of time.

17. The extravascular ICD of claim 16, wherein the processor is configured to determine an interval between the first identified beat and an immediately preceding beat of the first cardiac signal and determine the first identified beat is not a qualified beat for generating the beat template when the interval is less than a threshold interval.

18. The extravascular ICD of claim 17, wherein the processor is configured to determine the first identified beat is a qualified beat for generating the beat template when the estimated heart rate is less than the threshold heart rate, the determined amount of time between the first identified beat and the second identified beat is less than the threshold amount of time, and the interval is greater than or equal to the threshold interval.

19. The extravascular ICD of claim 17, wherein the processor is further configured to determine an amplitude of the first identified beat and determine the first identified beat is a not a qualified beat for generating the beat template when the amplitude is less than an amplitude threshold.

20. The extravascular ICD of claim 19, wherein the processor is further configured to determine the first identified beat is a qualified beat for generating the template when the estimated heart rate is less than the threshold heart rate, the determined amount of time between the first identified beat and the second identified beat is less than the threshold amount of time, the interval is greater than or equal to the threshold interval, and the amplitude is greater than or equal to the amplitude threshold.

21. The extravascular ICD of claim 19, wherein the processor is further configured to determine whether the first cardiac signal surrounding the first identified beat is noisy, and determine the first identified beat is not a qualified beat for generating the beat template when the first cardiac signal surrounding the first identified beat is determined to be noisy.

22. The extravascular ICD of claim 21, wherein the processor is further configured to determine the first identified beat is a qualified beat for generating the beat template when the estimated heart rate is less than the threshold heart rate, the determined amount of time between the first identified beat and the second identified beat is less than the threshold amount of time, the interval is greater than or equal to the threshold interval, the amplitude is greater than or equal to the amplitude threshold, and the first cardiac signal surrounding the first identified beat is determined to not be noisy.

23. The extravascular ICD of claim 17, wherein the processor is further configured to

determine whether the first cardiac signal surrounding the first identified beat is noisy, determine the first identified beat is not a qualified beat for generating the beat template when the first cardiac signal surrounding the first identified beat is determined to be noisy, and determine the first identified beat is a qualified beat for generating the beat template when the estimated heart rate is less than the threshold heart rate, the determined amount of time between the first identified beat and the second identified beat is less than the threshold amount of time, the interval is greater than or equal to the threshold interval, and the first cardiac signal surrounding the first identified beat is determined to not be noisy.

24. The extravascular ICD of claim 13, wherein the processor is configured to detect a tachycardia based at least on a comparison of beats to the generated beat template, the extravascular ICD further comprising therapy circuitry configured to provide an anti-tachycardia therapy from the extravascular location via at least a portion of the plurality of electrodes of the electrical stimulation lead in response to the processor detecting the tachycardia.

25. The extravascular ICD of claim 13, wherein the plurality of electrodes of the implantable electrical stimulation lead are configured to sense cardiac electrical signals from a subcutaneous location within a patient.

26. The extravascular ICD of claim 13, wherein the plurality of electrodes of the implantable electrical stimulation lead are configured to sense cardiac electrical signals from a substernal location within a patient.

27. An implantable cardiac device comprising:

sensing circuitry located within the housing and configured to obtain a first cardiac signal on a first electrode vector formed via a first subset of a plurality of extravascular electrodes and obtain a second cardiac signal on a second electrode vector formed via a second subset of the plurality of extravascular electrodes having at least one electrode different than the first electrode vector, wherein the second cardiac signal is sensed concurrently with the first cardiac signal;

a processor configured to;

identify beats within the first cardiac signal and the second cardiac signal,

apply beat qualification criteria to the beats within the first cardiac signal and the second cardiac signal to determine whether each of the beats is a qualified beat, wherein the beat criteria includes at least a heart rate criteria, a beat timing criteria between the beats in the first cardiac signal and corresponding beats in the second cardiac signal, and a beat interval criteria between successive beats in the first cardiac signal and successive beats in the second cardiac signal,

generate a beat template based on at least a portion of the beats determined to be qualified beats, and

detect a tachycardia based at least on a comparison of beats to the generated beat template; and

therapy circuitry configured to provide an anti-tachycardia therapy from the extravascular location via at least a portion of the plurality of extravascular electrodes of the electrical stimulation lead in response to the processor detecting the tachycardia.