Implantable cardiac devices and methods using an x/y counter

• US 8,965,530 B2
• Filed: 06/18/2014
• Issued: 02/24/2015
• Est. Priority Date: 05/26/2006
• Status: Active Grant

• Current Assignee: Cameron Health Inc (Boston Scientific Corporation)
• Original Assignee: Cameron Health Inc (Boston Scientific Corporation)
• Inventors: Sanghera, Rick, Allavatam, Venugopal
• Primary Examiner(s): Lavert, Nicole F
• Application Number:
  US14/307,756
• Publication Number:
  US 20140350631A1
• Time in Patent Office: 251 Days
• Field of Search: 607116-117, 600508-509
• US Class Current: 607/116
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/29 for permanent or long-term implantation
• CPC Class Codes: A61B 5/341 Vectorcardiography [VCG]
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61N 1/36535 controlled by body position or posture
• CPC Class Codes: A61N 1/368 comprising more than one electrode co-operating with different heart regions A61N1/3622, A61N1/3627 take precedence
• CPC Class Codes: A61N 1/37 Monitoring; Protecting
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: A61N 1/3704 Circuits specially adapted therefor, e.g. for sensitivity control
• CPC Class Codes: A61N 1/37247 User interfaces, e.g. input or presentation means
• 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

Methods, implantable medical devices and systems configured to perform analysis of captured signals from implanted electrodes to identify cardiac arrhythmias. In an illustrative embodiment, signals captured from two or more sensing vectors are analyzed, where the signals are captured with a patient in at least first and second body positions. Analysis is performed to identify primary or default sensing vectors and/or templates for event detection.

Claims

1. An implantable cardiac stimulus device configured for use with an implantable lead having a plurality of electrodes, the implantable cardiac stimulus device including operational circuitry having sensing inputs for coupling to at least three electrodes such that at least first and second sensing vectors are defined, the implantable cardiac stimulus device being configured to perform a sensing vector configuration sequence in which first and second sensing vectors are selected as primary and secondary sensing vectors, respectively, and the operational circuitry is configured to perform the following while sensing cardiac signals for the purpose of determining whether therapy should be administered:

maintain an X/Y counter in which X represents a quantity of recently detected cardiac cycles in which an arrhythmic condition is likely and Y represents a total number of recently detected cardiac cycles, while using the primary sensing vector to identify and analyze cardiac cycles for purposes of maintaining the X/Y counter; and

upon reaching a first threshold for X, and before reaching a second threshold for X, analyze at least one cardiac cycle using the secondary sensing vector to confirm whether an arrhythmic condition is likely.

2. The implantable cardiac stimulus device of claim 1 wherein the operational circuitry is further configured to continue maintaining the X/Y counter until reaching the second threshold for X, with the primary sensing vector and, if the cardiac cycles detected in the secondary sensing vector confirm that an arrhythmic condition is likely, determining that therapy is warranted.

3. The implantable cardiac stimulus device of claim 1 wherein the operational circuitry is configured such that the first threshold and the second threshold allow at least 8 cardiac cycles to be examined using the secondary sensing vector after the first threshold is reached and before the second threshold is reached.

4. The implantable cardiac stimulus device of claim 1 wherein the operational circuitry is configured such that, if the first threshold is met and the secondary sensing vector does not confirm that an arrhythmic condition is likely, the operational circuitry performs a vector switch such that the secondary sensing vector is identified as a new primary sensing vector.

5. The implantable cardiac stimulus device of claim 1 wherein the operational circuitry is configured such that:

the sensing vector configuration sequence comprises establishing a first template for use in analyzing detected cardiac cycles in the primary sensing vector;

the sensing vector configuration sequence comprises establishing a second template for use in analyzing detected cardiac cycles in the secondary sensing vector;

the step of using the primary sensing vector to identify and analyze cardiac cycles for purposes of maintaining the X/Y counter includes using the first template to distinguish normal cardiac cycles from arrhythmic cardiac cycles; and

the step of using the secondary sensing vector to identify and analyze cardiac cycles for purposes of maintaining the X/Y counter includes using the second template to distinguish normal cardiac cycles from arrhythmic cardiac cycles;

wherein the operational circuitry is configured to determine that therapy in response to an arrhythmia is warranted if neither the primary sensing vector and first template, nor the secondary sensing vector and second template indicate normal cardiac activity.

6. The implantable cardiac stimulus device of claim 5 wherein the operational circuitry is configured such that the first template is established with a recipient of the implantable cardiac stimulus device holding a first posture, and the second template is established with the recipient holding a second posture different from the first posture.

7. An implantable cardiac stimulus system comprising an implantable canister housing operational circuitry and a lead coupled to the implantable canister, the lead and/or canister including a plurality of electrodes coupled to the operational circuitry configured for use with an implantable lead having a plurality of electrodes, the operational circuitry having sensing inputs for coupling to at least three electrodes of the plurality of electrodes such that at least first and second sensing vectors are defined, the implantable cardiac stimulus device being configured to perform a sensing vector configuration sequence in which first and second sensing vectors are selected as primary and secondary sensing vectors, respectively, and the operational circuitry is configured to perform the following while sensing cardiac signals for the purpose of determining whether therapy should be administered:

maintain an X/Y counter in which X represents a quantity of recently detected cardiac cycles in which an arrhythmic condition is likely and Y represents a total number of recently detected cardiac cycles, while using the primary sensing vector to identify and analyze cardiac cycles for purposes of maintaining the X/Y counter; and

upon reaching a first threshold for X, and before reaching a second threshold for X, analyze at least one cardiac cycle using the secondary sensing vector to confirm whether an arrhythmic condition is likely.

8. The implantable cardiac stimulus system of claim 7 wherein the operational circuitry is further configured to continue maintaining the X/Y counter until reaching the second threshold for X, with the primary sensing vector and, if the cardiac cycles detected in the secondary sensing vector confirm that an arrhythmic condition is likely, determining that therapy is warranted.

9. The implantable cardiac stimulus system of claim 7 wherein the operational circuitry is configured such that the first threshold and the second threshold allow at least 8 cardiac cycles to be examined using the secondary sensing vector after the first threshold is reached and before the second threshold is reached.

10. The implantable cardiac stimulus system of claim 7 wherein the operational circuitry is configured such that, if the first threshold is met and the secondary sensing vector does not confirm that an arrhythmic condition is likely, the operational circuitry performs a vector switch such that the secondary sensing vector is identified as a new primary sensing vector.

11. The implantable cardiac stimulus system of claim 7 wherein the operational circuitry is configured such that:

the sensing vector configuration sequence comprises establishing a first template for use in analyzing detected cardiac cycles in the primary sensing vector;

the sensing vector configuration sequence comprises establishing a second template for use in analyzing detected cardiac cycles in the secondary sensing vector;

the step of using the primary sensing vector to identify and analyze cardiac cycles for purposes of maintaining the X/Y counter includes using the first template to distinguish normal cardiac cycles from arrhythmic cardiac cycles; and

the step of using the secondary sensing vector to identify and analyze cardiac cycles for purposes of maintaining the X/Y counter includes using the second template to distinguish normal cardiac cycles from arrhythmic cardiac cycles;

wherein the operational circuitry is configured to determine that therapy in response to an arrhythmia is warranted if neither the primary sensing vector and first template, nor the secondary sensing vector and second template indicate normal cardiac activity.

12. The implantable cardiac stimulus system of claim 11 wherein the operational circuitry is configured such that the first template is established with a recipient of the implantable cardiac stimulus device holding a first posture, and the second template is established with the recipient holding a second posture different from the first posture.

13. A method of operation in an implantable cardiac stimulus system comprising operational circuitry electrically coupled to a plurality of implantable electrodes, the operational circuitry having sensing inputs for coupling to at least three electrodes of the plurality of electrodes such that at least first and second sensing vectors are defined, the implantable cardiac stimulus device being configured to perform a sensing vector configuration sequence in which first and second sensing vectors are selected as primary and secondary sensing vectors, respectively, the method comprising:

the operational circuitry maintaining an X/Y counter in which X represents a quantity of recently detected cardiac cycles in which an arrhythmic condition is likely and Y represents a total number of recently detected cardiac cycles, while using the primary sensing vector to identify and analyze cardiac cycles for purposes of maintaining the X/Y counter; and

upon reaching a first threshold for X, and before reaching a second threshold for X, the operational circuitry analyzing at least one cardiac cycle using the secondary sensing vector to confirm whether an arrhythmic condition is likely.

14. The method of claim 13 further comprising the operational circuitry maintaining the X/Y counter after reaching the first threshold and until reaching the second threshold for X, with the primary sensing vector and, if the cardiac cycles detected in the secondary sensing vector confirm that an arrhythmic condition is likely, the operational circuitry determining that therapy is warranted.

15. The method of claim 13 wherein the first threshold and the second threshold are set to allow at least 8 cardiac cycles to be examined using the secondary sensing vector after the first threshold is reached and before the second threshold is reached using the primary sensing vector.

16. The method of claim 13 further comprising, if the first threshold is met and the secondary sensing vector does not confirm that an arrhythmic condition is likely, the operational circuitry switching sensing vectors such that the secondary sensing vector becomes the primary sensing vector.

17. The method of claim 13 wherein:

the sensing vector configuration sequence comprises establishing a first template for use in analyzing detected cardiac cycles in the primary sensing vector;

the sensing vector configuration sequence comprises establishing a second template for use in analyzing detected cardiac cycles in the secondary sensing vector;

the step of using the primary sensing vector to identify and analyze cardiac cycles for purposes of maintaining the X/Y counter includes using the first template to distinguish normal cardiac cycles from arrhythmic cardiac cycles; and

the step of using the secondary sensing vector to identify and analyze cardiac cycles for purposes of maintaining the X/Y counter includes using the second template to distinguish normal cardiac cycles from arrhythmic cardiac cycles;

wherein the operational circuitry is configured to determine that therapy in response to an arrhythmia is warranted if neither the primary sensing vector and first template, nor the secondary sensing vector and second template indicate normal cardiac activity.

18. The method of claim 17 wherein the first template is established with a recipient of the implantable cardiac stimulus device holding a first posture, and the second template is established with the recipient holding a second posture different from the first posture.