Methods and systems for detecting the presence of T-wave alternans

• US 7,881,792 B1
• Filed: 09/16/2005
• Issued: 02/01/2011
• Est. Priority Date: 09/16/2005
• Status: Expired due to Fees

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Farazi, Taraneh Ghaffari
• Primary Examiner(s): Layno; Carl H.
• Assistant Examiner(s): MORALES, JON ERIC C
• Application Number:
  US11/229,410
• Time in Patent Office: 1,964 Days
• Field of Search: 600/517, 600/515, 600/518, 607/9
• US Class Current: 607/25
• 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 1/36114 Cardiac control, e.g. by vagal stimulation stimulating the heart A61N1/362
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371

Abstract

Embodiments of the present invention relate to implantable systems, and method for use therein, that can detect T-wave alternans. In accordance with specific embodiments of the present invention, intrinsic premature contractions of the ventricles are detected, and at least one metric of T-waves is measured in a specified number of beats that follow each detected intrinsic premature contraction of the ventricles. A determination of whether T-wave alternans are present is made based on the measured T-wave metrics. In alternative embodiments, rather than waiting for intrinsic premature contractions of the ventricles, premature contractions of the ventricles are caused on demand by inducing premature atrial contractions. In still other embodiments, a patient'"'"'s vagus nerve is stimulated to simulate premature contractions of the ventricles. This abstract is not intended to be a complete description of, or limit the scope of, the invention.

Claims

1. In an implantable system, a method for detecting T-wave alternans, comprising:

(a) stimulating a patient'"'"'s vagus nerve to thereby simulate at least one premature contraction of the ventricles;

(b) measuring at least one metric of T-waves in a specified number of beats that follow each simulated premature contraction of the ventricles that is caused by stimulating the patients vagus nerve; and

(c) determining, based on the measured T-wave metrics, whether T-wave alternans are present.

2. The method of claim 1, wherein step (a) includes stimulating a patient'"'"'s vagus nerve to thereby simulate a plurality of premature contractions of the ventricles.

3. The method of claim 2, wherein steps (a) and (b) are repeated a plurality of times and wherein the patient'"'"'s heart is monitored for premature ventricular contractions to ensure that there are at least 3 beats in which a premature contraction of the ventricles does not occur between each stimulating of the vagus nerve at step (a).

4. The method of claim 1, wherein step (b) comprises measuring at least one metric of T-waves in M beats that follow each simulated premature contraction of the ventricles, where M is an integer between 2 and 10, inclusive.

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. An implantable system for detecting T-wave alternans, comprising:

means for stimulating a patient'"'"'s vagus nerve to thereby simulate premature contractions of the ventricles;

means for measuring at least one metric of T-waves in a specified number of beats that follow the simulated premature contractions of the ventricles that are caused by stimulating the patients vagus nerve; and

a TWA detector to determine, based on the measured T-wave metrics, whether T-wave alternans are present.

7. The system of claim 6, further including means for monitoring for premature ventricular contractions and means for ensuring that there are at least 3 beats in which a premature contraction of the ventricles does not occur between each stimulating of the vagus nerve.

8. The system of claim 6, wherein at least one metric of T-waves is measured in M beats that follow each simulated premature contraction of the ventricles, where M is an integer between 2 and 10, inclusive.

9. The system of claim 6, wherein said means for measuring measures 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.