Method for Discriminating Between Ventricular and Supraventricular Arrhythmias

• US 20090054938A1
• Filed: 10/28/2008
• Published: 02/26/2009
• 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., Bardy, Gust H., Warren, Jay A.
• Granted Patent: US 8,050,754 B2
• Time in Patent Office: Days
• 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 operation of an implantable medical device comprising:

the medical device estimating a rate of cardiac events for an implantee of the device;

if the estimated rate of cardiac events is in a predetermined range of likely arrhythmia, the medical device using morphology analysis to determine whether it positively identifies beats indicating treatable arrhythmias; and

;

if the estimated rate of cardiac events is above the predetermined range, the medical device determining that a detected event indicates therapy;

or

if the estimated rate of cardiac events is in the predetermined range and the morphology analysis positively identifies a treatable arrhythmia, the medical device determining that a detected event indicates therapy;

or

the medical device determining that a detected event does not indicate therapy;

and if the medical device determines that a predetermined number of detected events indicate therapy, the medical device charging a capacitor toward a level appropriate for cardiac therapy;

wherein the treatable arrhythmias include polymorphic ventricular tachycardia (PVT) and ventricular fibrillation (VF).

2. The method of claim 1 wherein PVT and VF are positively identified when a low correlation to a static template is calculated.

3. The method of claim 2 wherein PVT and VF are positively identified when, in addition to low correlation to the static template, a low correlation to a template captured following a triggering event is calculated.

4. The method of claim 2 wherein PVT and VF are positively identified when, in addition to low correlation to the static template, high variability in correlations to a template captured following a triggering event occurs.

5. The method of claim 2 wherein PVT and VF are positively identified when, in addition to low correlation to the static template, interval rate stability for a number of the implantee'"'"'s cardiac beats is low.

6. The method of claim 2 wherein PVT and VF are positively identified when, in addition to low correlation to the static template, high variability in correlations to the static template is observed.

7. The method of claim 1 wherein PVT and VF are positively identified when high variability in correlations to a static template is observed.

8. The method of claim 1 wherein PVT and VF are positively identified when a low correlation to a template captured following a triggering event is calculated.

9. The method of claim 1 wherein PVT and VF are positively identified when high variability in correlations to a template captured following a triggering event occurs.

10. The method of claim 1 wherein PVT and VF are positively identified when interval rate stability for a number of the implantee'"'"'s cardiac beats is low.

11. The method of claim 1 further comprising the medical device delivering shock therapy after the capacitor is charged to a level appropriate for cardiac therapy.

12. The method of claim 1 wherein the first and second views are defined by a set of electrodes comprising a first electrode disposed on the surface of an implantable defibrillator canister, the canister housing at least batteries and operational circuitry for performing cardiac signal analysis and arrhythmia treatment, and second and third electrodes disposed along a lead attached to the canister, wherein the lead is disposed only subcutaneously in the patient.

13. The method of claim 1 wherein the first and second views are defined by a set of electrodes comprising a first electrode disposed on the surface of an implantable defibrillator canister, the canister housing at least batteries and operational circuitry for performing cardiac signal analysis and arrhythmia treatment, and second and third electrodes disposed along a lead attached to the canister, wherein the lead is disposed transvenously in the patient such that at least one electrode is disposed internal to the patient'"'"'s heart.

14. A method of cardiac signal analysis comprising:

capturing a cardiac event using at least first and second vector views from electrodes implanted in a patient;

analyzing the captured cardiac event using a first method of analysis for the first vector view by comparing the captured cardiac event as seen from the first vector view to a stored sinus template of the first vector view;

analyzing the captured cardiac event using a second method of analysis for the second vector view, the second method including comparing the captured cardiac event to the cardiac complex of a cardiac event just previous to the captured cardiac event;

identifying whether an arrhythmia is likely occurring and, if so,

distinguishing a supraventricular arrhythmia from a ventricular originating arrhythmia using the results from the first and second methods to determine whether a ventricular originating arrhythmia is occurring; and

if a ventricular originating arrhythmia is occurring, directing cardiac defibrillation therapy to the patient.

15. The method of claim 14 wherein the first and second views are defined by a set of electrodes comprising a first electrode disposed on the surface of an implantable defibrillator canister, the canister housing at least batteries and operational circuitry for performing cardiac signal analysis and arrhythmia treatment, and second and third electrodes disposed along a lead attached to the canister, wherein the lead is disposed only subcutaneously in the patient.

16. The method of claim 14 wherein the first and second views are defined by a set of electrodes comprising a first electrode disposed on the surface of an implantable defibrillator canister, the canister housing at least batteries and operational circuitry for performing cardiac signal analysis and arrhythmia treatment, and second and third electrodes disposed along a lead attached to the canister, wherein the lead is disposed transvenously in the patient such that at least one electrode is disposed internal to the patient'"'"'s heart.

17. An implantable cardiac stimulus device system comprising:

a canister housing operational circuitry including at least a battery and a controller, the operational circuitry configured to observe electrical cardiac activity of the patient and, if determined necessary, to provide electrical cardiac stimulus to a patient if implanted in the patient;

a lead electrode assembly comprising at least one electrode for use in at least one of observing electrical cardiac activity and/or delivering electrical cardiac stimulus to a patient;

wherein the operational circuitry is configured to perform the step of observing electrical cardiac activity as follows in order to determine whether electrical cardiac stimulus is indicated;

capture a cardiac event using at least first and second vector views defined by electrodes included in the lead electrode assembly and/or located on the canister;

analyze the captured cardiac event using a first method of analysis for the first vector view by comparing the captured cardiac event as seen from the first vector view to a stored sinus template of the first vector view;

analyze the captured cardiac event using a second method of analysis for the second vector view, the second method including comparing the captured cardiac event to the cardiac complex of a cardiac event just previous to the captured cardiac event;

identify whether an arrhythmia is likely occurring and, if so,

distinguish a supraventricular arrhythmia from a ventricular originating arrhythmia using the results from the first and second methods to determine whether a ventricular originating arrhythmia is occurring; and

determine electrical cardiac stimulus is indicated if a ventricular originating arrhythmia is occurring.