Systems and methods related to ST segment monitoring by an implantable medical device

• US 8,467,862 B2
• Filed: 03/16/2011
• Issued: 06/18/2013
• Est. Priority Date: 03/30/2010
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Snell, Jay, Zhu, Bing, Hoberman, Katie, Krishnaswamy, Harish
• Primary Examiner(s): Koharski, Christopher D
• Assistant Examiner(s): VOORHEES, CATHERINE M
• Application Number:
  US13/049,805
• Publication Number:
  US 20110245699A1
• Time in Patent Office: 825 Days
• Field of Search: 600508-528, 607/4, 607/5, 607/9, 607/14
• US Class Current: 600/509
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

Cardiac activity is sensed over a plurality of heart beats defining a beat set. For each beat in the set, it is determined whether the beat is a non-classified beat (e.g., paced beat, a beat outside of a specified heart rate range or a PVC), or a classified beat. For each classified beat, it is determined whether the beat is a non-detect beat, a minor beat or a major beat. Counts of classified beats, non-classified beats, major beats, minor beats, and non-detect beats are maintained. The beat set is declared to be one of a non-classified set, a major set, a minor set or a non-detect set based on the relative counts of classified beats, non-classified beats, major beats, minor beats, and non-detect beats. Over a period of time, counts of beat-set types are maintained and entry into and exit from ST episodes are determined based on these beat-set counts.

Claims

1. A method of monitoring ST segments, said method comprising:

sensing electrical cardiac activity over a plurality of heart beats defining a beat set;

for each beat in the beat set, determining whether the beat of the ST segment is a non-classified beat or a classified beat;

for each classified beat, determining whether the beat is a non-detect beat, a minor beat or a major beat;

maintaining a count of classified beats, a count of non-classified beats, a count of major beats, a count of minor beats, and a count of non-detect beats;

declaring the beat set to be one of a non-classified set, a major set, a minor set or a non-detect set based on the relative counts of classified beats, non-classified beats, major beats, minor beats, and non-detect beats.

2. The method of claim 1 wherein determining whether the beat is a non-detect beat, a minor beat or a major beat comprises:

comparing the ST segment shift of the beat to each of a minor threshold and a major threshold;

determining the beat is a non-detect beat if the ST segment shift does not exceed the minor threshold;

determining the beat is a minor beat if the ST segment shift is at or above the minor threshold; and

determining the beat is a major beat if the ST segment shift is at or above the major threshold.

3. The method of claim 1 wherein a beat set is declared a non-classified set if the count of non-classified beats reaches a non-classified-beat value before the count of classified beats reaches a classified-beat value.

4. The method of claim 3 wherein the plurality of heart beats is Z, the classified-beat value is Y and the non-classified beat value is Z−

Y+1.

5. The method of claim 1 wherein a beat set is declared a major set if the count of classified beats reaches a classified-beat value before the count of non-classified beats reaches a non-classified-beat value, and the count of major beats reaches a major-beat value before either of the count of minor beats and the count of non-detect beats reaches its respective minor-beat value and non-detect beat value.

6. The method of claim 5 wherein:

the plurality of heart beats is Z, the classified-beat value is Y and the non-classified-beat value is Z−

Y+1; and

the major-beat value is X, the minor beat value is X and the non-detect beat value is Y−

X+1.

7. The method of claim 1 wherein a beat set is declared a minor set if the count of classified beats reaches a classified-beat value before the count of non-classified beats reaches a non-classified-beat value, and the count of minor beats reaches a minor-beat value before either of the count of major beats and the count of non-detect beats reaches its respective major-beat value and non-detect beat value.

8. The method of claim 7 wherein:

the plurality of heart beats is Z, the classified-beat value is Y and the non-classified-beat value is Z−

Y+1; and

the major-beat value is X, the minor-beat value is X and the non-detect-beat value is Y−

X+1.

9. The method of claim 1 wherein a beat set is declared a non-detect set if the count of classified beats reaches a classified-beat value before the count of non-classified beats reaches a non-classified-beat value, and the count of non-detect beats reaches a non-detect-beat value before either of the count of major beats and the count of minor beats reaches its respective major-beat value and minor-beat value.

10. The method of claim 9 wherein:

the plurality of heart beats is Z, the classified-beat value is Y and the non-classified-beat value is Z−

Y+1; and

the major-beat value is X, the minor-beat value is X and the non-detect-beat value is Y−

X+1.

11. The method of claim 1 further comprising maintaining a count of major sets, a count of minor sets, a count of non-detect sets and a count of non-classified sets.

12. The method of claim 11 wherein the count of major sets is incremented upon declaration of a major set and is initialized upon declaration of a non-detect set.

13. The method of claim 12 further comprising detecting a major ST episode onset when the count of major sets reaches a nominal value.

14. The method of claim 13 wherein upon declaration of a major ST episode, detecting an ST episode exit when a first number of non-classified sets are declared or a second number of non-detect sets are declared.

15. The method of claim 11 wherein the count of minor sets is incremented upon declaration of a major set or declaration of a minor set, and is initialized upon declaration of a non-detect set.

16. The method of claim 15 further comprising detecting a minor ST episode onset when the count of minor sets reaches a nominal value.

17. The method of claim 16 wherein upon declaration of a minor ST episode, detecting an ST episode exit when a first number of non-classified sets are declared or a second number of non-detect sets are declared.

18. The method of claim 11 wherein the count of non-detect sets is incremented upon declaration of a non-detect set, and is initialized upon declaration of a major set or declaration of a minor set.

19. The method of claim 11 wherein the count of non-classified sets is incremented upon declaration of a non-classified set.

20. The method of claim 1 wherein a non-classified beat corresponds to anyone of a paced beat, a beat outside of a specified heart rate range or a PVC.

21. A device for monitoring ST segments, said device comprising:

a sensor configured to sense electrical cardiac activity over a plurality of heart beats defining a beat set; and

a processor configured to;

for each beat in the beat set, determine whether the beat is a non-classified beat or a classified beat;

for each classified beat, determine whether the beat of the ST segment is a non-detect beat, a minor beat or a major beat;

maintain a count of classified beats, a count of non-classified beats, a count of major beats, a count of minor beats, and a count of non-detect beats;

declare the beat set to be one of a non-classified set, a major set, a minor set or a non-detect set based on the relative counts of classified beats, non-classified beats, major beats, minor beats, and non-detect beats.