SYSTEM AND METHOD FOR SEGMENTING A CARDIAC SIGNAL BASED ON BRAIN ACTIVITY

• US 20060224067A1
• Filed: 04/27/2006
• Published: 10/05/2006
• Est. Priority Date: 12/17/2004
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Werder, Jonathan C., Giftakis, Jonathon E., Graves, Nina M., Panken, Eric J., Carlson, David L.
• Granted Patent: US 8,108,038 B2
• Time in Patent Office: Days
• US Class Current: 600/483
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/02 Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/1135 by monitoring thoracic expansion
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/369 Electroencephalography [EEG] devices for psychotechnics A61B5/16
• CPC Class Codes: A61B 5/4094 Diagnosing or monitoring seizure diseases, e.g. epilepsy
• CPC Class Codes: A61N 1/36064 Epilepsy
• CPC Class Codes: A61N 1/36082 Cognitive or psychiatric applications, e.g. dementia or Alzheimer's disease
• CPC Class Codes: A61N 1/3611 Respiration control stimulating respiratory organs A61N1/3601
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters
• CPC Class Codes: A61N 1/37288 Communication to several implantable medical devices within one patient

Abstract

A medical device system that includes a brain monitoring element, cardiac monitoring element and a processor. The processor is configured to receive a brain signal from the brain monitoring element and a cardiac signal from the cardiac monitoring element. The processor is further configured to determine at least one reference point for a brain event time period by evaluation of the brain signal. The processor further identifies a first portion of the cardiac signal based on the at least one reference point of the brain event time period.

Claims

1. A medical device system comprising:

(a) a brain monitoring element for sensing activity of the brain and outputting a brain signal;

(b) a cardiac monitoring element for sensing activity of the heart and outputting a cardiac signal; and

(c) one or more processors in communication with the brain monitoring element and the cardiac monitoring element, the one or more processors configured to;

(i) receive the brain signal;

(ii) determine at least one reference point for a brain event time period by evaluation of the brain signal;

(iii) receive the cardiac signal; and

(iv) identify a first portion of the cardiac signal based on the at least one reference point of the brain event time period.

2. The medical device system of claim 1 wherein the reference point is the starting point of the brain event time period and the first portion comprises a pre-event portion.

3. The medical device system of claim 1 wherein the reference point is the ending point of the brain event time period and the first portion comprises a post-event portion.

4. The medical device system of claim 1 wherein determining the at least one reference point comprises determining a starting point of the brain event time period and an ending point of the brain event time period, and wherein the first portion of the cardiac signal comprises an event portion of the cardiac signal that is identified based on the starting point and the ending point of the brain event time period.

5. The medical device system of claim 1 wherein the one or more processors are further configured to identify a second portion of the cardiac signal based on the at least one reference point.

6. The medical device system of claim 4 wherein the one or more processors are further configured to:

(a) identify a pre-event portion of the cardiac signal based on the starting point of the brain event time period; and

(b) identify a post-event portion of the cardiac signal based on the ending point of the brain event time period.

7. The medical device system of claim 4 wherein the event portion of the cardiac signal comprises the cardiac signal from the starting point to the ending point.

8. The medical device system of claim 4 wherein the evaluation of the brain signal comprises executing a seizure detection algorithm, and wherein the brain event time period is an ictal time period.

9. The medical device system of claim 2 wherein the pre-event portion of the cardiac signal comprises at least a portion of the cardiac signal before the starting point.

10. The medical device system of claim 9, wherein the pre-event portion of the cardiac signal comprises the cardiac signal from a first period of time before the starting point to the starting point.

11. The medical device system of claim 10 wherein the pre-event portion comprises the cardiac signal from the first period of time before the starting point to a second period of time before the starting point.

12. The medical device system of claim 11 wherein the first period of time and the second period of time are programmable.

13. The medical device system of claim 3 wherein the post-event portion of the cardiac signal comprises at least a portion of the cardiac signal after the ending point.

14. The medical device system of claim 3 wherein the post-event portion of the cardiac signal comprises the cardiac signal from the ending point of the brain event time period to a third period of time after the ending point.

15. The medical device of claim 13 wherein the third period of time is programmable.

16. The medical device system of claim 1 further comprising a memory and wherein the one or more processors are further configured to store the first portion of the cardiac signal in the memory.

17. The medical device system of claim 5 wherein the one or more processors are further configured to determine a first metric of the first portion of the cardiac signal, and the one or more processors are further configured to determine a second metric of the second portion of the cardiac signal.

18. The medical device system of claim 17 wherein the one or more processors are further configured to:

(a) determine a second metric time related to the amount of time from the at least one reference point to the occurrence of the second portion;

(c) determine whether the second metric meets a predetermined criteria about its relationship to the first metric; and

(d) record in memory the second metric time when the second metric meets the predetermined criteria.

19. The medical device system of claim 18 wherein the predetermined criteria are met when the second metric equals the first metric.

20. The medical device system of claim 18 wherein the predetermined criteria are met when the second metric is within a specified range of the first metric.

21. The medical device system of claim 18 wherein the first portion comprises a pre-event portion and the second portion comprises a post-event portion, and wherein the first and second metrics comprise heart rate.

22. The medical device system of claim 17 wherein the one or more processors are further configured to compare the first metric to the second metric.

23. The medical device system of claim 22 wherein the one or more processors are configured to compare the first metric to the second metric by computing the percentage change from the first metric to the second metric.

24. The medical device system of claim 22 wherein the cardiac signal includes information about a heart rate, and wherein the first metric is a metric relating to the heart rate during the first portion of the cardiac signal and the second metric is a metric relating to the heart rate during the second portion of the cardiac signal.

25. The medical device system of claim 24 wherein the first metric is the mean heart rate over the first portion of the cardiac signal, and wherein the second metric is the mean heart rate over the second portion of the cardiac signal.

26. The medical device system of claim 24 wherein the first metric is the maximum heart rate over the first portion of the cardiac signal, and wherein the second metric is the maximum heart rate over the second portion of the cardiac signal.

27. The medical device system of claim 24 wherein the first metric is the standard deviation of the heart rate over the first portion of the cardiac signal, and wherein the second metric is the standard deviation of the heart rate over the second portion of the cardiac signal.

28. The medical device system of claim 24 wherein the first metric is the minimum heart rate over the first portion of the cardiac signal, and wherein the second metric is the minimum heart rate over the second portion of the cardiac signal.

29. The medical device system of claim 24 wherein the first metric is the median heart rate over the first portion of the cardiac signal, and wherein the second metric is the median heart rate over the second portion of the cardiac signal.

30. The medical device system of claim 22 wherein the at least one reference point comprises a starting point and an ending point of a brain event time period, and wherein the first portion of the cardiac signal comprises a pre-event portion of the cardiac signal based on the starting point of the brain event time period, and wherein the second portion of the cardiac signal comprises a post-event portion of the cardiac signal based on the ending point of the brain event time period.

31. The medical device system of claim 22 wherein the at least one reference point comprises a starting point and an ending point of a brain event time period, and wherein the first portion of the cardiac signal comprises a pre-event portion of the cardiac signal based on the starting point of the brain event time period, and wherein the second portion of the cardiac signal comprises an event portion of the cardiac signal based on the starting and ending points of the brain event time period.

32. The medical device system of claim 22 wherein the at least one reference point comprises a starting point and an ending point of a brain event time period, and wherein the first portion of the cardiac signal comprises an event portion of the cardiac signal based on the starting point and the ending point of the brain event time period, and wherein the second portion of the cardiac signal comprises a post-event portion of the cardiac signal based on the ending point of the brain event time period.

33. The medical device system of claim 32 wherein the post-event portion of the cardiac signal comprises the cardiac signal from the ending point of the brain event time period to a specified period of time after the ending point of the brain event time period.

34. The medical device system of claim 33 wherein the specified period of time is programmable.

35. The medical device system of claim 4 wherein the one or more processors determine the ending point of the brain event time period by evaluation of the brain signal.

36. The medical device system of claim 4 wherein the one or more processors determine the ending point of the brain event time period based on the starting point of the brain event time period.

37. The medical device system of claim 1 wherein the brain monitoring element, cardiac monitoring element and one or more processors are configured for implantation in a human body.

38. The medical device system of claim 18 wherein the system comprises an implantable unit comprising the brain monitoring element, the cardiac monitoring element and at least one implantable processor of the one or more processors, wherein the implantable processor is contained in a hermetically sealed housing for implantation in a human body, and wherein the system further comprises an external device, wherein the external device comprises a second processor of the one or more processors, and wherein the implantable unit comprises a telemetry transmitter, and wherein the external device includes a telemetry receiver for receiving information from the telemetry transmitter.

39. The medical device system of claim 38 wherein identifying the first portion of the cardiac signal and identifying the second portion of the cardiac signal are performed by the first implantable processor, and wherein determining the first and second metrics and comparing the first and second metrics is performed by the second processor.

40. The medical device system of claim 38 wherein identifying the first portion of the cardiac signal and identifying the second portion of the cardiac signal and determining the first and second metrics are performed by the first implantable processor, and wherein comparing the first and second metrics is performed by the second processor.

41. A medical device system comprising:

(a) a brain monitoring element for sensing activity of the brain and outputting a brain signal;

(b) a cardiac monitoring element for sensing activity of the heart and outputting a cardiac signal; and

(c) one or more processors in communication with the brain monitoring element and the cardiac monitoring element, the one or more processors configured to;

(i) receive the brain signal;

(ii) determine at least one reference point of a seizure event time period by evaluation of the brain signal;

(iii) receive the cardiac signal;

(iv) identify a first portion of the cardiac signal based on the at least one reference point, the first portion selected from the group consisting of pre-ictal, ictal and post-ictal portions;

(v) identify a second portion of the cardiac signal based on the at least one reference point, the second portion different from the first portion and selected from the group consisting of pre-ictal, ictal and post-ictal portions;

(vi) determine a first metric of the first portion;

(vii) determine a second metric of the second portion; and

(viii) compare the first metric to the second metric.

42. A method of monitoring brain and cardiac activity comprising:

(a) monitoring the brain and outputting a brain signal indicative of activity in the brain;

(b) monitoring the heart and outputting a cardiac signal indicative of activity in the heart;

(c) determining at least one reference point for a brain event time period by evaluation of the brain signal; and

(d) identifying a first portion of the cardiac signal based on the at least one reference point of the brain event time period.

43. The method of claim 42 wherein the reference point is the starting point of the brain event time period and the first portion comprises a pre-event portion.

44. The method of claim 42 wherein the reference point is the ending point of the brain event time period and the first portion comprises a post-event portion.

45. The method of claim 42 wherein determining the at least one reference point comprises determining a starting point of the brain event time period and an ending point of the brain event time period, and wherein the first portion of the cardiac signal comprises an event portion of the cardiac signal that is identified based on the starting point and the ending point of the brain event time period.

46. The method of claim 42 further comprising identifying a second portion of the cardiac signal based on one of the at least one reference point.

47. The method of claim 43 wherein the pre-event portion of the cardiac signal comprises at least a portion of the cardiac signal before the starting point.

48. The method of claim 47 wherein the pre-event portion comprises at least a portion of the cardiac signal before a period of time before the starting point.

49. The method of claim 42 further comprising storing the first portion of the cardiac signal in a memory.

50. The method of claim 46 further comprising determining a first metric of the first portion of the cardiac signal, and determining a second metric of the second portion of the cardiac signal.

51. The method of claim 50 further comprising comparing the first metric to the second metric.

52. The method of claim 51 wherein comparing the first metric to the second metric comprises computing the percentage change from the first metric to the second metric.

53. The method of claim 51 wherein the cardiac signal includes information about a heart rate, and wherein the first metric is a metric relating to the heart rate during the first portion of the cardiac signal and the second metric is a metric relating to the heart rate during the second portion of the cardiac signal.

54. The method of claim 53 wherein the first metric is the mean heart rate over the first portion of the cardiac signal, and wherein the second metric is the mean heart rate over the second portion of the cardiac signal.

55. The method of claim 53 wherein the first metric is the maximum heart rate over the first portion of the cardiac signal, and wherein the second metric is the maximum heart rate over the second portion of the cardiac signal.

56. The method of claim 53 wherein the first metric is the standard deviation of the heart rate over the first portion of the cardiac signal, and wherein the second metric is the standard deviation of the heart rate over the second portion of the cardiac signal.

57. The method of claim 53 wherein the first metric is the minimum of the heart rate over the first portion of the cardiac signal, and wherein the second metric is the minimum of the heart rate over the second portion of the cardiac signal.

58. The method of claim 53 wherein the first metric is the median heart rate over the first portion of the cardiac signal, and wherein the second metric is the median heart rate over the second portion of the cardiac signal.

59. The method of claim 53 wherein the at least one reference point comprises a starting point and an ending point of a brain event time period, and wherein the first portion of the cardiac signal comprises a pre-event portion of the cardiac signal based on the starting point of the brain event time period, and wherein the second portion of the cardiac signal comprises a post-event portion of the cardiac signal based on the ending point of the brain event time period.

60. The method of claim 53 wherein the at least one reference point comprises a starting point and an ending point of a brain event time period, and wherein the first portion of the cardiac signal comprises a pre-event portion of the cardiac signal based on the starting point of the brain event time period, and wherein the second portion of the cardiac signal comprises an event portion of the cardiac signal based on the starting and ending points of the brain event time period.

61. The method of claim 53 wherein the at least one reference point comprises a starting point and an ending point of a brain event time period, and wherein the first portion of the cardiac signal comprises an event portion of the cardiac signal based on the starting point and the ending point of the brain event time period, and wherein the second portion of the cardiac signal comprises a post-event portion of the cardiac signal based on the ending point of the brain event time period.

62. A computer readable medium containing executable instructions causing a processor to perform the following:

(a) receiving a brain signal from a brain monitoring element;

(b) receiving a cardiac signal from a cardiac monitoring element; and

(c) determining at least one reference point for a brain event time period by evaluation of the brain signal; and

(d) identifying a first portion of the cardiac signal based on the at least one reference point of the brain event time period.

63. The computer readable medium of claim 62 wherein the executable instructions further cause the processor to identify a second portion of the cardiac signal based on the at least one reference point.

64. The computer readable medium of claim 63 wherein the executable instructions further cause the processor to determine a first metric of the first portion of the cardiac signal, and determine a second metric of the second portion of the cardiac signal.

65. The computer readable medium of claim 64 wherein the executable instructions further cause the processor to compare the first metric to the second metric.