Pacing schemes for revealing T-wave alternans (TWA) at low to moderate heart rates

• US 7,738,956 B1
• Filed: 01/27/2006
• Issued: 06/15/2010
• Est. Priority Date: 01/27/2006
• Status: Expired due to Fees

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Bornzin, Gene A., Farazi, Taraneh Ghaffari
• Primary Examiner(s): Layno; Carl H
• Assistant Examiner(s): Porter, Jr.; Gary A
• Application Number:
  US11/341,086
• Time in Patent Office: 1,600 Days
• Field of Search: 607/9, 607/15, 607/25, 607/28
• US Class Current: 607/9
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/355 Detecting T-waves
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions

Abstract

Implantable systems that can monitor myocardial electrical stability, and methods for use therewith, are provided. Also provided are novel pacing sequences that are used in such monitoring. Such pacing sequences are designed to reveal alternans at low to moderate heart rates.

Claims

1. In an implantable system, a method for monitoring myocardial electrical stability, comprising:

(a) pacing a patient'"'"'s heart in accordance with a pacing sequence that includes a short beat set including N short beats that get successively shorter from the beginning to the end of the short beat set, followed by a regular beat set including a plurality of regular beats, wherein N is an integer greater than 2, wherein each said short beat is shorter than each said regular beat, and wherein each said short beat and each said regular beat is shorter than the patient'"'"'s intrinsic beat or the patient'"'"'s normal pacing length;

(b) measuring at least one metric of T-waves in two or more beats that follow each change in beat length;

(c) determining magnitudes of alternation based on the measured T-wave metrics; and

(d) monitoring myocardial electrical stability based on the determined magnitudes of alternation.

2. The method of claim 1, wherein step (d) comprises determining, based on the determined magnitudes of alternation, whether T-wave alternans are present.

3. The method of claim 1, wherein step (d) comprises tracking changes in the magnitudes of alternation as steps (a), (b) and (c) are repeated over time, to thereby track changes in myocardial electrical stability.

4. The method of claim 1, wherein each successive beat of the short beat set is a Δ

t shorter than the previous short beat.

5. The method of claim 1, wherein step (b) includes measuring at least one of the following T-wave metrics:

T-wave amplitude;

T-wave width;

T-wave slope;

T-wave area;

T-wave morphology;

QT interval; and

evoked QT interval.

6. In an implantable system, a method for monitoring myocardial electrical stability, comprising:

(a) pacing a patient'"'"'s heart in accordance with a pacing sequence that includes a short beat set including N short beats that get successively shorter from the beginning to the end of the short beat set, followed by a long beat set including K long beats, followed by a regular beat set including M regular beats, wherein N, K, and M are integers greater than 2, wherein each said short beat is shorter than each said regular beat and each said regular beat is shorter than each said long beat, and wherein each said short beat, each said long beat, and each said regular beat is shorter than the patient'"'"'s intrinsic beat or the patient'"'"'s normal pacing length;

(b) measuring at least one metric of T-waves in two or more beats that follow each change in beat length;

(c) determining magnitudes of alternation based on the measured T-wave metrics; and

(d) monitoring myocardial electrical stability based on the determined magnitudes of alternation.

7. The method of claim 6 wherein the plurality of long beats of the long beat set get successively shorter from the beginning to the end of the long beat set.

8. The method of claim 7 wherein each successive beat of the long beat set is a Δ

t shorter than the previous long beat.

9. The method of claim 6 wherein the plurality of long beats of the long beat set get successively longer from the beginning to the end of the long beat set.

10. The method of claim 9 wherein each successive beat of the long beat set is a Δ

t longer than the previous long beat.

11. The method of claim 6 wherein each successive beat of the short beat set is a Δ

t shorter than the previous short beat.

12. In an implantable system, a method for monitoring myocardial electrical stability, comprising:

(a) pacing a patient'"'"'s heart in accordance with a pacing sequence that includes a short beat set including N short beats that get successively longer from the beginning to the end of the short beat set, followed by a long beat set including K long beats, followed by a regular beat set including M regular beats, wherein N, K, and M are integers greater than 2, wherein each said short beat is shorter than each said regular beat and each said regular beat is shorter than each said long beat, and wherein each said short beat, each said long beat, and each said regular beat is shorter than the patient'"'"'s intrinsic beat or the patient'"'"'s normal pacing length;

(b) measuring at least one metric of T-waves in two or more beats that follow each change in beat length;

(c) determining magnitudes of alternation based on the measured T-wave metrics; and

(d) monitoring myocardial electrical stability based on the determined magnitudes of alternation.

13. The method of claim 12 wherein the plurality of long beats of the long beat set get successively shorter from the beginning to the end of the long beat set.

14. The method of claim 13 wherein each successive beat of the long beat set is a Δ

t shorter than the previous long beat.

15. The method of claim 12 wherein the plurality of long beats of the long beat set get successively longer from the beginning to the end of the long beat set.

16. The method of claim 15 wherein each successive beat of the long beat set is a Δ

t longer than the previous long beat.

17. The method of claim 12 wherein each successive beat of the short beat set is a Δ

t longer than the previous short beat.