Implantable cardiac device providing rapid pacing T wave alternan pattern detection and method

• US 7,245,968 B1
• Filed: 06/14/2004
• Issued: 07/17/2007
• Est. Priority Date: 06/28/2002
• Status: Expired due to Fees

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Park, Euljoon, Farazi, Taraneh
• Primary Examiner(s): Layno; Carl
• Assistant Examiner(s): Bertram; Eric D.
• Application Number:
  US10/868,240
• Time in Patent Office: 1,128 Days
• Field of Search: 607/9, 607/25, 607/26, 600/508, 600/509, 600/517
• US Class Current: 607/25
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion

Abstract

An implantable cardiac device that delivers electrical therapy to a patient'"'"'s heart determines if a T wave alternan pattern of the patient'"'"'s heart exists. The device includes a sensing circuit that generates an electrical signal including T waves representing paced electrical activity of the heart and a morphology detector that measures a metric of each T wave in the electrical signal. A T wave alternan pattern detector determines, responsive to the measured T wave metrics, if a paced activity T wave alternan pattern is present. The T wave alternan pattern detector may also detect for intrinsic T wave alternan patterns. A therapy control initiates suitable different responses for a paced T wave alternan pattern detection and an intrinsic T wave alternan pattern detection.

Claims

1. An implantable cardiac device comprising:

a T wave alternan pattern monitor that detects overdrive paced T wave alternan patterns and high rate intrinsic T wave alternan patterns; and

a therapy control that initiates a first responsive therapy when an overdrive paced T wave alternan pattern is detected and a second responsive therapy different from the first responsive therapy when a high rate intrinsic T wave alternan pattern is detected.

2. A method comprising:

detecting one of either overdrive paced T wave alternan patterns or high rate intrinsic T wave alternan patterns using an implantable cardiac device;

initiating a first responsive therapy when an overdrive paced T wave alternan pattern is detected; and

initiating a second responsive therapy different from the first responsive therapy when a high rate intrinsic T wave alternan pattern is detected.

3. The method of claim 2 wherein the first responsive therapy comprises long term preventive pacing.

4. The method of claim 2 wherein the second responsive therapy comprises at least one of defibrillation shock therapy and aggressive overdrive pacing.

5. The method of claim 2 wherein the first responsive therapy and the second responsive therapy are initiated by the implantable cardiac device.

6. The method of claim 2 wherein detecting overdrive paced T wave alternan patterns comprises:

measuring the heart rate of a heart to obtain an intrinsic rate; and

applying pacing pulses to the heart at a pacing rate above the intrinsic rate if the intrinsic rate is below a given accelerated rate.

7. An implantable cardiac stimulation device comprising:

a heart rate measuring circuit operative to measure the intrinsic heart rate of a heart having a normal heart rate at rest;

a pulse generator operative to apply pacing pulses to the heart;

means for detecting the presence of T-wave alternans; and

a processor operative to initiate an overdrive paced T-wave analysis by the T-wave alternans detecting means by periodically overdrive pacing the heart for a period of time if the intrinsic rate is below a set high-rate intrinsic rate that is above the normal heart rate, and to initiate an high-rate intrinsic T-wave analysis, different then the overdrive paced T-wave analysis, if the intrinsic rate is above the set high-rate intrinsic rate.

8. The device of claim 7 further comprising a therapy control that initiates a first responsive therapy when an overdrive paced T wave alternan pattern is detected and a second responsive therapy different from the first responsive therapy when a high-rate intrinsic T wave alternan pattern is detected.

9. The device of claim 8 wherein the second therapy response is more aggressive than the first therapy response.

10. The device of claim 7 wherein the means for detecting the presence of T-wave alternans comprises:

a sensing circuit that generates an electrical signal including T waves representing electrical activity of the heart;

a morphology detector that receives the electrical signal from the sensing circuit and that measures a metric of each T wave in the electrical signal; and

a T wave alternan pattern detector that receives the measured T wave metrics from the morphology detector and that determines, responsive to the measured T wave metrics if a T wave alternan pattern is present.

11. The device of claim 10 wherein, for an overdrive paced T-wave analysis, the T wave alternan pattern detector determines if the overdrive paced activity T wave alternan pattern is a sustained T wave alternan pattern.

12. The device of claim 10 wherein the T wave alternan pattern detector provides a histogram of T wave amplitude difference between successive T waves occurring within a sliding window and determines if a T wave alternan pattern is present responsive to a shape in the histogram.

13. The device of claim 7 wherein the pulse generator applies pacing pulses to an atrium of the heart.