Detecting abnormal activation of heart

• US 5,891,047 A
• Filed: 03/14/1997
• Issued: 04/06/1999
• Est. Priority Date: 03/14/1997
• Status: Expired due to Term

• Current Assignee: Spacelabs Healthcare, Inc. (OSI Systems Incorporated)
• Original Assignee: Cambridge Heart Inc.
• Inventors: Gomis, Pedro, Lander, Paul
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US08/818,131
• Time in Patent Office: 753 Days
• Field of Search: 600/515-518, 600/520
• US Class Current: 600/516
• CPC Class Codes: A61B 5/282 Holders for multiple electrodes for introduction into the body A61B5/287
• CPC Class Codes: A61B 5/35 by template matching

Abstract

Abnormal cardiac activity in a patient may be detected by acquiring an electrocardiogram waveform associated with a first level of physiologic activity of the patient and an electrocardiogram waveform associated with a second, different level of physiologic activity of the patient. QRS complexes of the electrocardiogram waveforms are compared to identify an abnormal portion of the QRS complex of the electrocardiogram waveform associated with the second level of physiologic activity. The abnormal portion of the QRS complex is processed to detect abnormal physiologic activity.

Claims

1. A method of detecting abnormal cardiac activity in a patient, the method comprising:

acquiring an electrocardiogram waveform associated with a first level of physiologic activity of the patient and an electrocardiogram waveform associated with a second, different level of physiologic activity of the patient; and

comparing QRS complexes of the electrocardiogram waveforms to identify an abnormal portion of the QRS complex of the electrocardiogram waveform associated with the second level of physiologic activity.

2. The method of claim 1, further comprising stressing the patient'"'"'s heart to produce the second level of physiologic activity.

3. The method of claim 2, wherein:

stressing the patient'"'"'s heart comprises performing a physiological stress test on the patient, the physiological stress test including an exercise stage and a non-exercise stage,

the first level of physiologic activity is associated with the non-exercise stage of the stress test, and

the second level of physiologic activity is associated with the exercise stage of the stress test.

4. The method of claim 2, wherein stressing the patient'"'"'s heart comprises using pharmaceutical stress.

5. The method of claim 1, further comprising:

identifying subensembles of beats in the electrocardiogram waveforms corresponding to the first and second levels of physiologic activity; and

processing each subensemble of beats to produce a representative beat;

wherein the step of comparing comprises comparing QRS complexes of the representative beats of the electrocardiogram waveforms to identify an abnormal portion of the QRS complex of the electrocardiogram waveform associated with the second level of physiologic activity.

6. The method of claim 5, wherein the step of processing each subensemble of beats comprises producing a representative beat using subensemble averaging.

7. The method of claim 5, wherein the step of processing each subensemble of beats comprises producing a representative beat by computing a measure of statistical central tendency from the subensemble of beats.

8. The method of claim 1, wherein the step of comparing comprises subtracting a QRS complex of the electrocardiogram associated with the first level of physiologic activity from a QRS complex of the electrocardiogram associated with the second level of physiologic activity and using results of the subtraction in identifying the abnormal portion of the QRS complex of the electrocardiogram waveform associated with the second level of physiologic activity.

9. The method of claim 1, further comprising generating a model of a QRS complex of the electrocardiogram waveform associated with the first level of physiologic activity and using the model in comparing QRS complexes of the electrocardiogram waveforms.

10. The method of claim 9, wherein the step of comparing comprises subtracting the model of the QRS complex of the electrocardiogram associated with the first level of physiologic activity from a QRS complex of the electrocardiogram associated with the second level of physiologic activity and using results of the subtraction in identifying the abnormal portion of the QRS complex of the electrocardiogram waveform associated with the second level of physiologic activity.

11. The method of claim 1, further comprising generating models of QRS complexes of the electrocardiogram waveforms, wherein the step of comparing comprises subtracting from the QRS complex of each electrocardiogram waveform the model of the QRS complex of that waveform and using results of the subtractions in identifying the abnormal portion of the QRS complex of the electrocardiogram waveform associated with the second level of physiologic activity.

12. The method of claim 1, further comprising determining a root-mean-square amplitude of the abnormal portion of the QRS complex and using the determined amplitude to detect further abnormal cardiac activity.

13. The method of claim 1, further comprising determining a duration of the abnormal portion of the QRS complex and using the determined duration to detect further abnormal cardiac activity.

14. The method of claim 1, further comprising measuring an energy of the abnormal portion of the QRS complex and using the measured energy to detect further abnormal cardiac activity.

15. The method of claim 1, further comprising measuring timing of the abnormal portion of the QRS complex relative to the QRS complex and using the measured timing to detect further abnormal cardiac activity.

16. The method of claim 1, further comprising measuring bandwidth of the abnormal portion of the QRS complex relative to the QRS complex and using the measured bandwidth to detect further abnormal cardiac activity.

17. The method of claim 1, further comprising:

acquiring electrocardiogram waveforms associated with other levels of physiologic activity of the patient;

comparing QRS complexes of the electrocardiogram waveforms to identify abnormal portions of the QRS complexes of the electrocardiogram waveform associated with the second level of physiologic activity and the electrocardiogram waveforms associated with other levels of physiologic activity; and

processing the abnormal portions of the QRS complexes to detect further abnormal cardiac activity.

18. The method of claim 17, wherein processing portions of the QRS complexes comprises comparing the abnormal portions of the QRS complexes.

19. The method of claim 17, wherein processing portions of the QRS complexes comprises measuring a parameter of each of the abnormal portions of the QRS complexes and comparing parameters associated with different QRS complexes.

20. The method of claim 17, wherein processing portions of the QRS complexes further comprises identifying a trend in abnormal portions of the QRS complexes for changing levels of physiologic activity.

21. The method of claim 17, further comprising generating models of QRS complexes of the electrocardiogram waveforms, wherein comparing QRS complexes of the electrocardiogram waveforms to identify abnormal portions of the QRS complexes of the electrocardiogram waveform associated with the second level of physiologic activity and the electrocardiogram waveforms associated with other levels of physiologic activity comprises subtracting from the QRS complex of each electrocardiogram waveform the model of the QRS complex of that waveform and using results of the subtractions in identifying the abnormal portion of the QRS complex of the electrocardiogram waveform associated with the second level of physiologic activity.

22. The method of claim 1, further comprising detecting myocardial ischemia by analyzing the abnormal portion of the QRS complex.

23. The method of claim 22, further comprising determining a quantitative measure of a degree of myocardial ischemia by analyzing the abnormal portion of the QRS complex.

24. The method of claim 22, further comprising determining a location of the myocardial ischemia by analyzing the abnormal portion of the QRS complex.

25. A system for detecting abnormal cardiac activity in a patient, the system comprising:

means for acquiring an electrocardiogram waveform associated with a first level of physiologic activity of the patient and an electrocardiogram waveform associated with a second, different level of physiologic activity of the patient;

means for comparing QRS complexes of the electrocardiogram waveforms to identify an abnormal portion of the QRS complex of the electrocardiogram.

26. The system of claim 25, further comprising means for stressing the patient'"'"'s heart to produce the second level of physiologic activity.

27. The system of claim 26, wherein:

the means for stressing the patient'"'"'s heart comprises means for performing a physiological stress test on the patient, the physiological stress test including an exercise stage and a non-exercise stage,

the first level of physiologic activity is associated with the non-exercise stage of the stress test, and

the second level of physiologic activity is associated with the exercise stage of the stress test.

28. The system of claim 26, further comprising means for generating a model of a QRS complex of the electrocardiogram waveform associated with the first level of physiologic activity, wherein the means for comparing uses the model in comparing QRS complexes of the electrocardiogram waveforms.

29. The system of claim 28, wherein the means for comparing comprises means for subtracting the model of the QRS complex of the electrocardiogram associated with the first level of physiologic activity from a QRS complex of the electrocardiogram associated with the second level of physiologic activity and using results of the subtraction in identifying the abnormal portion of the QRS complex of the electrocardiogram waveform associated with the second level of physiologic activity.

30. The system of claim 26, wherein the means for stressing the patient'"'"'s heart comprises means for using pharmaceutical stress.

31. The system of claim 25, further comprising:

means for identifying subensembles of beats in the electrocardiogram waveforms corresponding to the first and second levels of physiologic activity; and

means for processing each subensemble of beats to produce a representative beat;

wherein the means for comparing comprises means for comparing QRS complexes of the representative beats of the electrocardiogram waveforms to identify an abnormal portion of the QRS complex of the electrocardiogram waveform associated with the second level of physiologic activity.

32. The system of claim 31, wherein the means for processing each subensemble of beats comprises means for producing a representative beat using subensemble averaging.

33. The system of claim 31, wherein the means for processing each subensemble of beats comprises means for producing a representative beat by computing a measure of statistical central tendency from the subensemble of beats.

34. The system of claim 25, wherein the means for comparing comprises means for subtracting a QRS complex of the electrocardiogram associated with the first level of physiologic activity from a QRS complex of the electrocardiogram associated with the second level of physiologic activity and using results of the subtraction in identifying the abnormal portion of the QRS complex of the electrocardiogram waveform associated with the second level of physiologic activity.

35. The system of claim 25, further comprising means for generating models of QRS complexes of the electrocardiogram waveforms, wherein the means for comparing comprises means for subtracting from the QRS complex of each electrocardiogram waveform the model of the QRS complex of that waveform and using results of the subtractions in identifying the abnormal portion of the QRS complex of the electrocardiogram waveform associated with the second level of physiologic activity.

36. The system of claim 25, further comprising means for determining a root-mean-square amplitude of the abnormal portion of the QRS complex and using the determined amplitude to detect further abnormal cardiac activity.

37. The system of claim 25, further comprising means for determining a duration of the abnormal portion of the QRS complex and using the determined duration to detect further abnormal cardiac activity.

38. The system of claim 25, further comprising means for measuring an energy of the abnormal portion of the QRS complex and using the measured energy to detect further abnormal cardiac activity.

39. The system of claim 25, further comprising means for measuring timing of the abnormal portion of the QRS complex relative to the QRS complex and using the measured timing to detect further abnormal cardiac activity.

40. The system of claim 25, further comprising means for measuring bandwidth of the abnormal portion of the QRS complex relative to the QRS complex and using the measured bandwidth to detect further abnormal cardiac activity.

41. The system of claim 25, further comprising:

means for acquiring electrocardiogram waveforms associated with other levels of physiologic activity of the patient;

means for comparing QRS complexes of the electrocardiogram waveforms to identify abnormal portions of the QRS complexes of the electrocardiogram waveform associated with the second level of physiologic activity and the electrocardiogram waveforms associated with other levels of physiologic activity; and

means for processing the abnormal portions of the QRS complexes to detect further abnormal cardiac activity.

42. The system of claim 41, wherein the means for processing comprises means for comparing the abnormal portions of the QRS complexes.

43. The system of claim 41, wherein the means for processing comprises means for measuring a parameter of each of the abnormal portions of the QRS complexes and comparing parameters associated with different QRS complexes.

44. The system of claim 41, wherein the means for processing further comprises means for identifying a trend in abnormal portions of the QRS complexes for changing levels of physiologic activity.

45. The system of claim 41, further comprising means for generating models of QRS complexes of the electrocardiogram waveforms, wherein the means for comparing comprises means for subtracting from the QRS complex of each electrocardiogram waveform the model of the QRS complex of that waveform and using results of the subtractions in identifying the abnormal portion of the QRS complex of the electrocardiogram waveform associated with the second level of physiologic activity.

46. The system of claim 25, further comprising means for detecting myocardial ischemia by analyzing the abnormal portion of the QRS complex.

47. The system of claim 46, further comprising means for determining a quantitative measure of a degree of myocardial ischemia by analyzing the abnormal portion of the QRS complex.

48. The system of claim 46, further comprising means for determining a location of the myocardial ischemia by analyzing the abnormal portion of the QRS complex.