T-wave alternans train spotter

• US 7,725,172 B2
• Filed: 01/12/2004
• Issued: 05/25/2010
• Est. Priority Date: 01/13/2003
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: De Bruyn, Henricus Willem M., Rouw, Mattias, Van Groeningen, Christianus J. J. E.
• Primary Examiner(s): Layno; Carl H.
• Assistant Examiner(s): Heller; Tammie K
• Application Number:
  US10/755,694
• Publication Number:
  US 20040186527A1
• Time in Patent Office: 2,325 Days
• Field of Search: 600/509, 600/516
• US Class Current: 600/516
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions

Abstract

A method and system for detecting T-wave alternans for use in an implanted medical device uses wave transformation of QT intervals to obtain a reliable measure of TWA. In one embodiment, an array provides alternating sign multiplication factors which are applied respectively to n consecutive QT values. Each successive QT value is high pass filtered and moved sequentially through a queue so that each cycle each of the n QT values is multiplied by one of the factors; the products are summed and made absolute to provide an alternans match value. The alternans match is compared with a noise threshold signal, and alternans is declared when the match exceeds the threshold by a predetermined amount. The array is programmable and can be varied, providing a high degree of flexibility to optimize the test for the patient.

Claims

1. An implantable medical system, comprising:

an implantable medical device having a substantially hermetic housing;

a detecting means for detecting QT interval time values, disposed within the housing;

a memory means for storing said detected time values in a queue;

a transformation array program containing elements providing for operating on n of said timings, coupled to said detecting circuit, wherein said transform array program includes pattern factors in the form of alternating positive and negative factors and wherein n is a positive integer;

a control means coupled to said memory means and said transformation array for multiplying said stored time values by said positive and negative pattern factors and for producing a value indicative of the degree of T-wave alternans using the multiplications; and

a threshold circuit operating on said indicative value and detecting T-wave alternans as a function of said indicative value.

2. The system of claim 1, wherein said control means operates to form a queue of the n most recent of said stored time values.

3. The system of claim 2, wherein said transform array program comprises n alternating sign multipliers.

4. The system of claim 3, wherein said transform array program comprises means for obtaining a summation of products of multiplying said stored time values by said alternating sign multipliers.

5. The system of claim 4, further comprising an absolute value means for converting said summation to an absolute value.

6. The system of claim 5, further comprising a comparator, wherein said threshold circuit provides a noise threshold and said comparator compares said noise threshold value and said summation absolute value.

7. The system of claim 6, further comprising means for high pass filtering of said stored time values.

8. The system of claim 7, wherein said elements of said transform array program provide said high pass filtering of said stored time values.