Method for Discriminating Between Ventricular and Supraventricular Arrhythmias

• US 20080132965A1
• Filed: 02/11/2008
• Published: 06/05/2008
• Est. Priority Date: 05/29/2003
• Status: Active Grant

• Current Assignee: Cameron Health Inc (Boston Scientific Corporation)
• Original Assignee: Cameron Health Inc (Boston Scientific Corporation)
• Inventors: Ostroff, Alan H., Bardy, Gust H., Warren, Jay A.
• Granted Patent: US 8,942,802 B2
• Time in Patent Office: Days
• US Class Current: 607/14
• 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 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• 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
• CPC Class Codes: A61N 1/3987 characterised by the timing or triggering of the shock

Abstract

The present invention is directed toward a detection architecture for use in implantable cardiac rhythm devices. The detection architecture of the present invention provides methods and devices for discriminating between arrhythmias. Moreover, by exploiting the enhanced specificity in the origin of the identified arrhythmia, the detection architecture can better discriminate between rhythms appropriate for device therapy and those that are not.

Claims

1. A method of operating an implantable medical device configured for implantation in an implantee comprising:

capturing a cardiac signal from implantable electrodes and detecting a cardiac event;

determining whether a cardiac event rate falling within an enhanced analysis zone is occurring and, if so,

determining whether the cardiac event has a poor morphology correlation relative to data captured from cardiac events occurring in an elevated rate range and, if so, determining that the cardiac event indicates cardiac stimulus;

determining whether the cardiac event illustrates a QRS width that is greater than a predetermined threshold and, if so, determining that the cardiac event indicates cardiac stimulus;

otherwise, determining that the cardiac event does not indicate cardiac stimulus.

2. The method of claim 1 wherein the step of determining whether a cardiac event rate falling within an enhanced analysis zone is occurring includes determining whether the cardiac event rate falls within a zone between first and second thresholds, the first threshold defining a boundary between low rates and the enhanced analysis zone, and the second threshold defining a boundary between the enhanced analysis zone and rates automatically indicating stimulus.

3. The method of claim 1 wherein the data captured from cardiac events occurring in an elevated rate range is a dynamic template that changes as new cardiac events occur.

4. The method of claim 1 wherein the enhanced analysis zone includes cardiac rates at or above the range of 170-260 beats per minute

5. The method of claim 1 further comprising, if the cardiac event rate falls above the enhanced analysis zone, determining that the cardiac event indicates stimulus.

6. The method of claim 1 further comprising, if the cardiac event rate falls below the enhanced analysis zone, determining that the cardiac event does not indicate stimulus.

7. The method of claim 1 wherein all cardiac signals are captured by the use of electrodes disposed outside of the ribcage of the implantee.

8. An implantable cardiac stimulus device comprising a canister housing operational circuitry and a lead system coupled to the canister, the operational circuitry being electrically connected to a plurality of sensing electrodes disposed as part of the lead system and/or canister, the operational circuitry configured to perform a cardiac signal analysis method comprising the following steps:

detecting a cardiac event by observation of electrical signals captured using at least some of the sensing electrodes;

determining whether the captured electrical signals indicate a cardiac event rate falling within an enhanced analysis zone is occurring and, if so,

determining whether the cardiac event has a poor morphology correlation relative to data captured from cardiac events occurring in an elevated rate range and, if so, determining that the cardiac event indicates cardiac stimulus;

determining whether the cardiac event illustrates a QRS width that is greater than a predetermined threshold and, if so, determining that the cardiac event indicates cardiac stimulus;

otherwise, determining that the cardiac event does not indicate cardiac stimulus.

9. The implantable cardiac stimulus device of claim 8 wherein the operational circuitry is configured such that the step of determining whether captured electrical signals indicate a cardiac event rate falling within an enhanced analysis zone is occurring includes determining whether the cardiac event rate falls within a zone between first and second thresholds, the first threshold defining a boundary between low rates and the enhanced analysis zone, and the second threshold defining a boundary between the enhanced analysis zone and rates automatically indicating stimulus.

10. The implantable cardiac stimulus device of claim 8 wherein the operational circuitry is configured such that the data captured from cardiac events occurring in an elevated rate range is a dynamic template that changes as new cardiac events occur.

11. The implantable cardiac stimulus device of claim 8 wherein the operational circuitry is configured such that the enhanced analysis zone includes cardiac rates at or above the range of 170-260 beats per minute

12. The implantable cardiac stimulus device of claim 8 wherein the operational circuitry is further configured such that, if the cardiac event rate falls above the enhanced analysis zone, the operational circuitry determines that the cardiac event indicates stimulus.

13. The implantable cardiac stimulus device of claim 8 wherein the operational circuitry is further configured such that, if the cardiac event rate falls below the enhanced analysis zone, the operational circuitry determines that the cardiac event does not indicate stimulus.

14. A method of operating an implantable medical device configured for implantation in an implantee comprising:

capturing a cardiac signal from implantable electrodes disposed in the implantee and detecting a cardiac event;

performing a tiered decision-making process including the following steps;

a) determining whether the cardiac event has a poor morphology correlation relative to data captured from cardiac events occurring in an elevated rate range and, if so, determining that the cardiac event indicates cardiac stimulus;

b) determining whether the cardiac event illustrates a QRS width that is greater than a predetermined threshold and, if so, determining that the cardiac event indicates cardiac stimulus;

otherwise, determining that the cardiac event does not indicate cardiac stimulus.

15. The method of claim 14 further comprising estimating a rate for cardiac activity of the implantee and characterizing the rate in the following manner:

if the rate is below a first threshold, determining the rate is non-tachyarrhythmic and that no cardiac stimulus is indicated;

if the rate is between the first threshold and the second threshold, performing the tiered decision making process to determine whether individual cardiac events indicate cardiac stimulus;

or

if the rate is above the second threshold, determining the rate is in a malignant tachyarrhythmic or ventricular fibrillation zone and that cardiac stimulus is indicated by cardiac events.

16. The method of claim 15 wherein all cardiac signals are captured by the use of electrodes disposed outside of the ribcage of the implantee.

17. The method of claim 15 further comprising, as part of the tiered decision making process, determining whether the cardiac event has a poor morphology correlation relative to a stored static template relating to a normal sinus rhythm cardiac event and, if so, determining that the cardiac event indicates cardiac stimulus.

18. The method of claim 14 wherein all cardiac signals are captured by the use of electrodes disposed outside of the ribcage of the implantee.

19. The method of claim 14 further comprising, as part of the tiered decision making process, determining whether the cardiac event has a poor morphology correlation relative to a stored static template relating to a normal sinus rhythm cardiac event and, if so, determining that the cardiac event indicates cardiac stimulus.