APPARATUS AND METHOD FOR IDENTIFYING MYOCARDIAL ISCHEMIA USING ANALYSIS OF HIGH FREQUENCY QRS POTENTIALS

• US 20090318820A1
• Filed: 08/02/2007
• Published: 12/24/2009
• Est. Priority Date: 08/03/2006
• Status: Active Grant

• Current Assignee: BSP Medical Limited
• Original Assignee: Bsp Biological Signal Processing Ltd.
• Inventors: Toledo, Eran, Beker, Amir, Bregman-Amitai, Orna
• Granted Patent: US 8,538,510 B2
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/366 Detecting abnormal QRS complex, e.g. widening
• CPC Class Codes: A61B 5/4884 inducing physiological or psychological stress, e.g. applications for stress testing
• CPC Class Codes: A61B 5/6804 Garments; Clothes
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B

Abstract

Detecting cardiac ischemia by detecting local changes in high frequency ECG parameters. Local changes may be, for example, local reduction in RMS of high frequency components, for example, during a stress test.

Claims

1. A method for analyzing ECG signals, comprising:

(a) providing at least one ECG signal recorded from a body;

(b) determining the value of at least one parameter of a high frequency band of said ECG signal; and

(c) generating an alert responsive to a local change of the parameter value during a test.

2. A method according to claim 1, wherein said alert comprises diagnosing ischemia.

3. A method according to claim 1, wherein said parameter is an amplitude related parameter.

4. A method according to claim 1, wherein said local change is a change compared to a value under similar conditions at a different time.

5. A method according to claim 1, wherein said local change is a change compared to the signal at a short time before.

6. A method according to claim 1, wherein said test comprises a stress test.

7. A method according to claim 6, wherein said local change is a change relative to a maximum stress condition.

8. A method according to claim 6, wherein said local change is a change relative to a maximum signal condition.

9. A method according to claim 1, wherein said test comprises a monitoring event.

10. A method according to claim 1, wherein said test comprises a treatment event.

11. A method according to claim 1, wherein said test comprises a monitoring of at least 1 hour.

12. A method according to claim 1, wherein said test comprises a monitoring of at least 2 hours.

13. A method according to claim 1, wherein generating an alert comprises performing an additional test.

14. A method according to claim 1, wherein generating an alert comprises generating an alert responsive to at least one additional physiological considerations.

15. A method according to claim 14, wherein said at least one additional physiological consideration comprises a low-frequency ECG.

16. A method according to claim 14, wherein said at least one additional physiological consideration comprises an absolute change in a high frequency parameter.

17. A method according to claim 1, wherein the ECG signal is sampled from a plurality of leads.

18. A method according to claim 17, wherein a lead with a high level of noise is discarded from the diagnosis.

19. A method according to claim 17, wherein an ischemia diagnosis depends on the analysis results of multiple leads.

20. A method according to claim 19, wherein a lead value is weighted according to its noise level.

21. A method of detecting an ischemic event, comprising:

(a) analyzing a high frequency band of an ECG signal collected from a plurality of heartbeats to detect a change in at least one parameter;

(b) identifying the change as being indicative of a potential ischemic event;

(c) further analyzing data associated with said potential event to increase a reliability of said identifying.

22. A method according to claim 21, wherein said analyzing comprises analyzing after a stress test starts.

23. A method according to claim 21, wherein said analyzing comprises analyzing during a non-stress situation.

24. A method according to claim 21, wherein said analyzing comprises identifying a transient stress event based on a change in heart rate.

25. A method according to claim 21, wherein said further analyzing comprises analyzing said ECG signal.

26. A method according to claim 25, wherein said further analyzing comprises analyzing said a high frequency band of said ECG signal.

27. A method according to claim 21, wherein said further analyzing comprises analyzing additional data.

28. A method according to claim 21, wherein said analyzing comprises scanning a stream of ECG data for said change.

29. A method according to claim 21, wherein said analyzing comprises predetermining one or more points in time to analyze for said change.

30. A method according to claim 21, wherein said identifying comprises identifying a change indicative of a reduction in conduction velocity.

31. A method according to claim 21, wherein said identifying comprises identifying a change indicative of an increase in conduction velocity.

32. A method of detecting an ischemic event, comprising:

(a) scanning a high frequency band of an ECG signal collected from a plurality of heartbeats to detect a change in at least one parameter, at a point in time not pre-specified; and

(b) identifying the change as being indicative of a potential ischemic event.

33. A method according to claim 32, wherein said change comprises a local change.

34. A method according to claim 32, wherein said change comprises a reduction in HF amplitude.

35. A method according to claim 32, comprising further analyzing data associated with said potential event to increase a reliability of said identifying.

36. A method according to claim 32, wherein said scanning comprises scanning in a monitoring setting.

37. A method according to claim 32, wherein said scanning comprises scanning in a stress-testing setting.

38. Apparatus for ECG signal analysis, comprising:

(a) an input for an ECG signal;

(b) a high-frequency band extractor which extracts a HF band from said signal;

(c) a filter configured to analyze said HF band and detect a local change; and

(d) an output which generates an output signal responsive to a detected change.

39. Apparatus according to claim 38, including a processor configured to analyze low frequency components of said ECG signal.

40. Apparatus according to claim 38, mounted as a wearable ECG monitor.

41. Apparatus according to claim 38, configured as a part of an implantable device.

42. Apparatus according to claim 38, configured as a part of an exercise stress test system.

43. Apparatus according to claim 38, wherein said filter analyses said HF band using a cross-correlation method to detect said local change.

44. Apparatus according to claim 38, wherein said filter analyses said HF band to determine a change in a kurtosis parameter.

45. Apparatus according to claim 38, comprising a memory adapted to store a reference value from a different session.