T-WAVE ALTERNANS TRAIN SPOTTER

• US 20100145404A1
• Filed: 02/18/2010
• Published: 06/10/2010
• 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.
• Granted Patent: US 8,175,695 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• 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. A method of determining an indication of alternans in an implanted medical device, comprising:

cyclically obtaining measures of QT intervals;

high pass filtering the measures to substantially remove predetermined components associated with a predetermined change from cycle to cycle;

processing said filtered measures cyclically by wave transformation, and obtaining from said transformation a measure of alternans match;

determining when said measure of alternans match indicates alternans.

2. The method of claim 1, further comprising using a cardiac pacemaker as said medical device, and changing at least one pacing parameter of said pacemaker in response to an indication of alternans.

3. The method of claim 2, further comprising storing at least one transformation array in said pacemaker, and using said array in said processing step.

4. The method of claim 2, further comprising providing memory for a plurality of transformation arrays in said pacemaker, and programming respective arrays into said memory.

5. The method of claim 2, wherein said determining step comprises comparing said measure of alternans match to a predetermined alternans threshold.

6. The method of claim 5, further comprising generating a noise threshold signal and using said signal as said alternans threshold.

7. The method of claim 3, further comprising an array having n multipliers, and selecting n as a number between 3 and 10.

8. The method of claim 7, further comprising an array with multiplier factors that provide for high pass filtering of the measures.

9. The method of claim 7, further comprising making the alternans match an absolute value.

10. A method of determining an indication of T-wave alternans using an implantable medical device, comprising:

using said device to detect values of T-wave signals;

storing said detected time values in a queue within said device;

operating on n of said stored time values using a transform program within said device including pattern factors in the form of alternating positive and negative factors by multiplying said stored time values by said positive and negative pattern factors to produce a value indicative of a degree of T-wave alternans;

detecting the occurrence of T-wave alternans responsive to said indicative value exceeding a defined threshold value;

storing a record of said occurrence of T-wave alternans within said device, and

transmitting said record to an device external device.

11. The method of claim 10, wherein storing said detected time values comprises a queue of the n most recent of said stored time values.

12. The method of claim 11, wherein said transform array program comprises n alternating sign multipliers.

13. The method of claim 12, wherein operating on n of said stored time values comprises obtaining a summation of the products of multiplying said stored time values by said alternating sign multipliers.

14. The method of claim 13, wherein further comprising converting said summation to an absolute value.

15. The method of claim 14, wherein detecting the occurrence of T-wave alternans comprises defining a noise threshold value and comparing said noise threshold value and said summation absolute value.

16. The method of claim 15, further comprising high pass filtering of said stored time values.

17. The method of claim 16, comprising using said transform array program to provide said high pass filtering of said stored time values.

18. A method of detecting and responding to T-wave alternans using an implantable heart stimulator, comprising:

using said stimulator to detect values of T-wave signals;

storing said detected time values in a queue within said stimulator;

operating on n of said stored time values using a transform program within said stimulator including pattern factors in the form of alternating positive and negative factors by multiplying said stored time values by said positive and negative pattern factors to produce a value indicative of a degree of T-wave alternans;

detecting the occurrence of T-wave alternans responsive to said indicative value exceeding a defined threshold value; and

responsive to said detected occurrence of T-wave alternans, modifying an operating parameter of said stimulator.

19. A method according to claim 18, wherein operating on n of said stored time values comprises obtaining a summation of the products of multiplying said stored time values by alternating sign multipliers.

20. A method according to claim 19, wherein modifying an operating parameter of said stimulator comprises changing a stimulation parameter of the stimulator.