Vector switching in an implantable cardiac stimulus system

• US 8,825,157 B2
• Filed: 06/23/2008
• Issued: 09/02/2014
• Est. Priority Date: 07/28/2003
• Status: Active Grant

• Current Assignee: Cameron Health Inc (Boston Scientific Corporation)
• Original Assignee: Cameron Health Inc (Boston Scientific Corporation)
• Inventors: Warren, Jay A., Bardy, Gust H.
• Primary Examiner(s): GETZOW, SCOTT M
• Application Number:
  US12/144,462
• Publication Number:
  US 20080275521A1
• Time in Patent Office: 2,262 Days
• Field of Search: 607 4- 28, 600508-520
• US Class Current: 607/27
• CPC Class Codes: A61B 5/276 Protection against electrode failure
• CPC Class Codes: A61B 5/29 for permanent or long-term implantation
• CPC Class Codes: A61B 5/341 Vectorcardiography [VCG]
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/3706 Pacemaker parameters stimulation threshold A61N1/371
• CPC Class Codes: A61N 1/3925 Monitoring; Protecting
• CPC Class Codes: A61N 1/3987 characterised by the timing or triggering of the shock

Abstract

The implantable cardiac treatment system of the present invention is capable of choosing the most appropriate electrode vector to sense within a particular patient. In certain embodiments, the implantable cardiac treatment system determines the most appropriate electrode vector for continuous sensing based on which electrode vector results in the greatest signal amplitude, or some other useful metric such as signal-to-noise ratio (SNR). The electrode vector possessing the highest quality as measured using the metric is then set as the default electrode vector for sensing. Additionally, in certain embodiments of the present invention, a next alternative electrode vector is selected based on being generally orthogonal to the default electrode vector. In yet other embodiments of the present invention, the next alternative electrode vector is selected based on possessing the next highest quality metric after the default electrode vector. In some embodiments, if analysis of the default vector is ambiguous, the next alternative electrode vector is analyzed to reduce ambiguity.

Claims

1. A method of cardiac signal analysis in an implantable cardiac stimulus device comprising:

implanting, into the patient, a cardiac stimulus system comprising a canister and a lead assembly, the lead assembly including a plurality of electrodes thereon and the canister including at least one electrode thereon for use in cardiac activity sensing;

selecting for default use a first electrode pair defining a first sensing vector by observing a cardiac signal metric for a plurality of available sensing vectors and using the first electrode pair as a default electrode pair when observing cardiac activity of the patient;

attempting to form a template representative of normal sinus rhythm for the patient using the first sensing vector after the first electrode pair has been selected for default use;

failing to form the template representative of normal sinus rhythm using the first sensing vector and, in response thereto,

changing the default electrode pair to a different pair of electrodes defining a sensing vector other than the first sensing vector;

wherein the first electrode pair is selected for default use on the basis of having a better cardiac signal metric when compared to other available sense vectors.

2. The method of claim 1 further comprising delivering cardiac stimulus to the patient if the patient is determined to be experiencing a treatable cardiac arrhythmia.

3. The method of claim 1 wherein the step of implanting is performed such that the canister and lead assembly are subcutaneously implanted with no portion thereof inserted into a chamber of the patient'"'"'s heart, the patient'"'"'s heart muscle, or the patient'"'"'s vasculature.

4. The method of claim 1 further comprising analyzing cardiac signals captured using the default electrode pair to determine whether a treatable cardiac arrhythmia is occurring and, if so, delivering cardiac stimulus to the patient.

5. The method of claim 4 wherein the step of analyzing cardiac signals captured using the default electrode pair is performed such that one of three outcomes can be achieved following detection of a cardiac event using the default electrode pair:

a determination that a treatable cardiac arrhythmia is occurring;

a determination that no treatable cardiac arrhythmia is occurring;

or

an identification of ambiguity resulting from analysis of cardiac signals captured using the default electrode pair.

6. The method of claim 5 wherein, if an outcome including an identification of ambiguity follows detection of a given cardiac event occurs, the method further comprises performing subsequent analysis on cardiac signal data captured at the time of the given cardiac event using an electrode pair different from the default electrode pair to resolve the ambiguity.

7. An implantable cardiac stimulus system comprising a canister and a lead assembly configured for attachment thereto, the canister including at least a first electrode and the lead assembly including at least second and third electrodes, the canister housing operational circuitry configured to perform cardiac signal analysis and to provide cardiac stimulus if needed, the operational circuitry including at least a microcontroller and input and output circuitry for controlling inputs and outputs using the first, second and/or third electrodes such that the microcontroller can operatively select a default electrode combination for use in sensing, and wherein the operational circuitry is configured to perform method steps, while implanted in a patient, including at least the following steps:

selecting for default usage a first electrode combination defining a first sensing vector by observing a cardiac signal metric for a plurality of available sensing vectors and using the first electrode combination as the default electrode pair when observing cardiac activity of the patient;

attempting to form a template representative of normal sinus rhythm for the patient using the first sensing vector after the first electrode pair has been selected for default use;

failing to form the template representative of normal sinus rhythm using the first sensing vector and, in response thereto,

changing the default electrode combination to a different set of electrodes defining a sensing vector different from first sensing vector;

wherein;

the first electrode pair is selected for default use on the basis of having a better cardiac signal metric when compared to other available sense vectors.

8. The system of claim 7 wherein the operational circuitry is further configured to deliver cardiac stimulus to the patient if the patient is determined to be experiencing a treatable cardiac arrhythmia.

9. The system of claim 7 wherein the operational circuitry is further configured to analyze cardiac signals captured using the default electrode combination to determine whether a treatable cardiac arrhythmia is occurring and, if so, to deliver cardiac stimulus to the patient.

10. The system of claim 9 wherein the operational circuitry is configured such that performing the step of analyzing cardiac signals captured using the default electrode pair is performed such that one of three outcomes can be achieved following detection of a cardiac event using the default electrode combination:

a determination that a treatable cardiac arrhythmia is occurring;

a determination that no treatable cardiac arrhythmia is occurring;

or

an identification of ambiguity resulting from analysis of cardiac signals captured using the default electrode combination.

11. The system of claim 10 wherein the operational circuitry is configured such that, if an outcome including an identification of ambiguity follows detection of a given cardiac event occurs, subsequent analysis is performed on cardiac signal data captured at the time of the given cardiac event using an electrode combination different from the default electrode combination to resolve the ambiguity.

12. A method of cardiac signal analysis in an implantable cardiac stimulus device comprising:

implanting, into the patient, a cardiac stimulus system comprising a canister and a lead assembly, the lead assembly including a plurality of electrodes thereon and the canister including at least one electrode thereon for use in cardiac activity sensing;

performing one or more steps for identifying a first electrode pair that defines a first sensing vector for default usage when observing cardiac activity of the patient;

attempting to form a template representative of normal sinus rhythm for the patient using the first sensing vector after the first electrode pair has been selected for default use;

failing to form the template representative of normal sinus rhythm using the first sensing vector and, in response thereto,

performing one or more steps for changing the default electrode pair to a different pair of electrodes defining a sensing vector other than the first sensing vector;

wherein;

the first electrode pair is identified for default use on the basis of having a better cardiac signal metric when compared to other available sense vectors.

13. The method of claim 12 further comprising delivering cardiac stimulus to the patient if the patient is determined to be experiencing a treatable cardiac arrhythmia.

14. The method of claim 12 wherein the step of implanting is performed such that the canister and lead assembly are subcutaneously implanted with no portion thereof inserted into a chamber of the patient'"'"'s heart, the patient'"'"'s heart muscle, or the patient'"'"'s vasculature.

15. The method of claim 12 further comprising analyzing cardiac signals captured using the default electrode pair to determine whether a treatable cardiac arrhythmia is occurring and, if so, delivering cardiac stimulus to the patient.

16. The method of claim 15 wherein the step of analyzing cardiac signals captured using the default electrode pair is performed such that one of three outcomes can be achieved following detection of a cardiac event using the default electrode pair:

a determination that a treatable cardiac arrhythmia is occurring;

a determination that no treatable cardiac arrhythmia is occurring;

or

an identification of ambiguity resulting from analysis of cardiac signals captured using the default electrode pair.

17. The method of claim 16 wherein, if an outcome including an identification of ambiguity follows detection of a given cardiac event occurs, the method further comprises performing subsequent analysis on cardiac signal data captured at the time of the given cardiac event using an electrode pair different from the default electrode pair to resolve the ambiguity.