Method for discriminating between ventricular and supraventricular arrhythmias

• US 8,942,802 B2
• Filed: 02/11/2008
• Issued: 01/27/2015
• Est. Priority Date: 05/29/2003
• Status: Active Grant

• Current Assignee: Cameron Incorporated (Schlumberger NV)
• Original Assignee: Cameron Incorporated (Schlumberger NV)
• Inventors: Ostroff, Alan H., Warren, Jay A., Bardy, Gust H.
• Primary Examiner(s): GETZOW, SCOTT M
• Application Number:
  US12/029,272
• Publication Number:
  US 20080132965A1
• Time in Patent Office: 2,542 Days
• Field of Search: 607 4- 28, 600508-519
• US Class Current: 607/5
• 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 cardiac stimulus device comprising a housing coupled to at least one lead, with a plurality of implantable electrodes, the housing containing operational circuitry for performing signal analysis and delivering therapy when indicated, the device configured for implantation in an implantee, the method comprising:

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

calculating a cardiac event rate relative to the detected cardiac event;

comparing the cardiac event rate to one or more rate thresholds;

determining that the cardiac event rate falls within an enhanced analysis zone;

based on determining that the cardiac event rate falls within the enhanced analysis zone, analyzing morphology correlation between the detected cardiac event and an elevated rate template representative of a cardiac complex with a rate between 170 and 260 bpm;

finding that the cardiac event has high morphology correlation to the elevated rate template and is therefore not treatable on the basis of rate and morphology correlation combined;

next,

determining whether the cardiac event illustrates a QRS width that is less than a predetermined threshold width; and

finding the QRS width is greater than the predetermined threshold and determining that the cardiac event indicates a cardiac condition that requires treatment, despite its correlation to the elevated rate template;

wherein the elevated rate template is a dynamic template which represents an immediately preceding cardiac event.

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

3. 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;

calculating a cardiac event rate relative to the detected cardiac event;

determining the cardiac event rate falls within an enhanced analysis zone;

analyzing morphology correlation of the cardiac event relative to an elevated rate template representative of a cardiac complex with a rate between 170 and 260 bpm;

determining that the cardiac event has high morphology correlation relative to the elevated rate template and is therefore not treatable on the basis of rate and morphology correlation combined;

analyzing whether the cardiac event illustrates a QRS width that is greater than a predetermined threshold; and

one of;

determining that the cardiac event is narrower than the predetermined threshold and, in view thereof, determining that the cardiac event does not indicate cardiac stimulus;

or

determining that the cardiac event is wider than the predetermined threshold and determining that the cardiac event indicates a cardiac condition that requires treatment despite its correlation to the elevated rate template

wherein the elevated rate template is a dynamic template which represents an immediately preceding cardiac event.

4. A method of operating an implantable cardiac stimulus device comprising a housing coupled to at least one lead, with a plurality of implantable electrodes, the housing containing operational circuitry for performing signal analysis and delivering therapy when indicated, the device configured for implantation in an implantee, the method comprising:

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

calculating a cardiac event rate relative to the detected cardiac event;

performing a tiered decision-making process configured to include the following steps;

a) determining whether the cardiac event rate is in a predefined elevated rate range;

b) analyzing whether the cardiac event has a high morphology correlation relative to an elevated rate template representative of a cardiac complex with a rate between 170 and 260 bpm;

c) analyzing whether the cardiac event illustrates a QRS width that is greater than a predetermined threshold;

wherein the tiered decision making process includes;

after finding that a) is true, performing b;

after finding that b) yields high correlation, while the event rate is in the predefined elevated rate range, determining that the combination of rate and morphology correlation does not support therapy delivery without more information and therefore invoking c) and, when c) is invoked,

further finding the cardiac event is wider than the predetermined threshold, and determining that the cardiac event indicates cardiac stimulus even though the cardiac event correlates to the elevated rate template;

wherein the elevated rate template is a dynamic template which represents an immediately preceding cardiac event.

5. The method of claim 4 wherein all cardiac signals are captured by the use of electrodes disposed outside of the ribcage of the implantee.