System and method for segmenting a cardiac signal based on brain stimulation

• US 8,209,009 B2
• Filed: 04/27/2007
• Issued: 06/26/2012
• Est. Priority Date: 12/17/2004
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Giftakis, Jonathon E., Graves, Nina M., Rise, Mark Turner
• Primary Examiner(s): Lavert, Nicole F
• Application Number:
  US11/796,576
• Publication Number:
  US 20070265536A1
• Time in Patent Office: 1,887 Days
• Field of Search: 607/5, 607/9, 600/544
• US Class Current: 607/9
• 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 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• 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 5/349 Detecting specific parameters of the electrocardiograph cycle
• 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
• CPC Class Codes: A61N 1/3962 in combination with another heart therapy
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

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

Claims

1. A medical device system comprising:

(a) a brain stimulating element for stimulating the brain during a stimulation event time period;

(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 stimulating element and the cardiac monitoring element, the one or more processors configured to;

(i) determine at least one reference point for the stimulation event time period by evaluation of a stimulation state indicating stimulation of the brain by the brain stimulating element;

(ii) receive a recording of the cardiac signal; and

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

2. The medical device system of claim 1 wherein the reference point is the starting point of the stimulation 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 stimulation 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 stimulation event time period and an ending point of the stimulation event time period, and wherein the first portion of the cardiac signal recording comprises an event portion of the cardiac signal recording that is identified based on the starting point and the ending point of the stimulation 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 recording 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 recording based on the starting point of the stimulation event time period; and

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

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

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

9. The medical device system of claim 8, wherein the pre-event portion of the cardiac signal recording comprises the cardiac signal recording from a first period of time before the starting point to the starting point.

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

11. The medical device system of claim 10 wherein the first period of time and the second period of time are programmable.

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

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

14. The medical device of claim 12 wherein the third period of time is programmable.

15. 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 recording in the memory.

16. 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 recording, and the one or more processors are further configured to determine a second metric of the second portion of the cardiac signal recording.

17. The medical device system of claim 16 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;

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

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

18. The medical device system of claim 17 wherein the predetermined criteria are met when the second metric equals the first metric.

19. The medical device system of claim 17 wherein the predetermined criteria are met when the second metric is within a specified range of the first metric.

20. The medical device system of claim 17 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.

21. The medical device system of claim 16 wherein the one or more processors are further configured to compare the first metric to the second metric.

22. The medical device system of claim 21 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.

23. The medical device system of claim 21 wherein the cardiac signal recording 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 recording and the second metric is a metric relating to the heart rate during the second portion of the cardiac signal recording.

24. The medical device system of claim 23 wherein the first metric is the mean heart rate over the first portion of the cardiac signal recording, and wherein the second metric is the mean heart rate over the second portion of the cardiac signal recording.

25. The medical device system of claim 23 wherein the first metric is the maximum heart rate over the first portion of the cardiac signal recording, and wherein the second metric is the maximum heart rate over the second portion of the cardiac signal recording.

26. The medical device system of claim 23 wherein the first metric is the standard deviation of the heart rate over the first portion of the cardiac signal recording, and wherein the second metric is the standard deviation of the heart rate over the second portion of the cardiac signal recording.

27. The medical device system of claim 23 wherein the first metric is the minimum heart rate over the first portion of the cardiac signal recording, and wherein the second metric is the minimum heart rate over the second portion of the cardiac signal recording.

28. The medical device system of claim 23 wherein the first metric is the median heart rate over the first portion of the cardiac signal recording, and wherein the second metric is the median heart rate over the second portion of the cardiac signal recording.

29. The medical device system of claim 21 wherein the at least one reference point comprises a starting point and an ending point of a stimulation event time period, and wherein the first portion of the cardiac signal recording comprises a pre-event portion of the cardiac signal recording based on the starting point of the stimulation event time period, and wherein the second portion of the cardiac signal recording comprises a post-event portion of the cardiac signal recording based on the ending point of the stimulation event time period.

30. The medical device system of claim 21 wherein the at least one reference point comprises a starting point and an ending point of a stimulation event time period, and wherein the first portion of the cardiac signal recording comprises a pre-event portion of the cardiac signal recording based on the starting point of the stimulation event time period, and wherein the second portion of the cardiac signal recording comprises an event portion of the cardiac signal recording based on the starting and ending points of the stimulation event time period.

31. The medical device system of claim 21 wherein the at least one reference point comprises a starting point and an ending point of a stimulation event time period, and wherein the first portion of the cardiac signal recording comprises an event portion of the cardiac signal recording based on the starting point and the ending point of the stimulation event time period, and wherein the second portion of the cardiac signal recording comprises a post-event portion of the cardiac signal recording based on the ending point of the stimulation event time period.

32. The medical device system of claim 31 wherein the post-event portion of the cardiac signal recording comprises the cardiac signal recording from the ending point of the brain event time period to a specified period of time after the ending point of the stimulation event time period.

33. The medical device system of claim 32 wherein the specified period of time is programmable.

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

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

36. The medical device system of claim 17 wherein the system comprises an implantable unit comprising the brain stimulating 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.

37. The medical device system of claim 36 wherein identifying the first portion of the cardiac signal recording and identifying the second portion of the cardiac signal recording 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.

38. The medical device system of claim 36 wherein identifying the first portion of the cardiac signal recording and identifying the second portion of the cardiac signal recording 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.

39. The medical device system of claim 1 wherein the one or more processors determine the at least one reference point by evaluation of a brain stimulation signal representative of the stimulation state.

40. The medical device system of claim 39 wherein the brain stimulation signal comprises a continuous signal representative of the stimulation state.

41. The medical device system of claim 39 wherein the brain stimulation signal comprises a binary signal representative of the stimulation state.

42. The medical device system of claim 1 wherein the one or more processors determine the at least one reference point by evaluation of a stimulation event log representative of the stimulation state.

43. A medical device system comprising:

(a) a brain stimulating element for stimulating the brain during a stimulation event time period;

(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 stimulating element and the cardiac monitoring element, the one or more processors configured to;

(i) determine at least one reference point of the stimulation event time period by evaluation of a stimulation state indicating stimulation of the brain by the brain stimulating element;

(ii) receive a recording of the cardiac signal;

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

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

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

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

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

44. A method of stimulating brain and monitoring cardiac activity comprising:

(a) stimulating the brain during a stimulation event time period;

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

(c) determining, with electronic circuitry, at least one reference point for the brain stimulation event time period by evaluation of a stimulation state indicating stimulation of the brain by the brain stimulating element; and

(d) identifying, with the electronic circuitry, a first portion of a recording of the cardiac signal based on the at least one reference point of the brain stimulation event time period.

45. The method of claim 44 wherein the reference point is the starting point of the brain stimulation event time period and the first portion comprises a pre-event portion.

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

47. The method of claim 44 wherein determining the at least one reference point comprises determining a starting point of the brain stimulation event time period and an ending point of the brain stimulation event time period, and wherein the first portion of the cardiac signal recording comprises an event portion of the cardiac signal recording that is identified based on the starting point and the ending point of the brain stimulation event time period.

48. The method of claim 44 further comprising identifying a second portion of the cardiac signal recording based on one of the at least one reference point.

49. The method of claim 45 wherein the pre-event portion of the cardiac signal recording comprises at least a portion of the cardiac signal recording before the starting point.

50. The method of claim 49 wherein the pre-event portion comprises at least a portion of the cardiac signal recording before a period of time before the starting point.

51. The method of claim 44 further comprising storing the first portion of the cardiac signal recording in a memory.

52. The method of claim 48 further comprising determining a first metric of the first portion of the cardiac signal recording, and determining a second metric of the second portion of the cardiac signal recording.

53. The method of claim 52 further comprising comparing the first metric to the second metric.

54. The method of claim 53 wherein comparing the first metric to the second metric comprises computing the percentage change from the first metric to the second metric.

55. The method of claim 53 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 recording and the second metric is a metric relating to the heart rate during the second portion of the cardiac signal recording.

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

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

58. The method of claim 55 wherein the first metric is the standard deviation of the heart rate over the first portion of the cardiac signal recording, and wherein the second metric is the standard deviation of the heart rate over the second portion of the cardiac signal recording.

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

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

61. The method of claim 55 wherein the at least one reference point comprises a starting point and an ending point of a brain stimulation event time period, and wherein the first portion of the cardiac signal recording comprises a pre-event portion of the cardiac signal recording based on the starting point of the brain stimulation event time period, and wherein the second portion of the cardiac signal recording comprises a post-event portion of the cardiac signal recording based on the ending point of the brain stimulation event time period.

62. The method of claim 55 wherein the at least one reference point comprises a starting point and an ending point of a brain stimulation event time period, and wherein the first portion of the cardiac signal recording comprises a pre-event portion of the cardiac signal recording based on the starting point of the brain stimulation event time period, and wherein the second portion of the cardiac signal recording comprises an event portion of the cardiac signal recording based on the starting and ending points of the brain stimulation event time period.

63. The method of claim 55 wherein the at least one reference point comprises a starting point and an ending point of a brain stimulation event time period, and wherein the first portion of the cardiac signal recording comprises an event portion of the cardiac signal recording based on the starting point and the ending point of the brain stimulation event time period, and wherein the second portion of the cardiac signal recording comprises a post-event portion of the cardiac signal recording based on the ending point of the brain stimulation event time period.

64. A non-transitory computer readable medium containing executable instructions causing a processor to perform the following:

(a) signal a brain stimulating element to stimulate a brain during a stimulation event time period;

(b) receive a recording of a cardiac signal from a cardiac monitoring element; and

(c) determine, with the processor, at least one reference point for the brain stimulation event time period by evaluation of a stimulation state indicating stimulation of the brain by the brain stimulating element; and

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

65. The computer readable medium of claim 64 wherein the executable instructions further cause the processor to identify a second portion of the cardiac signal recording based on the at least one reference point.

66. The computer readable medium of claim 65 wherein the executable instructions further cause the processor to determine a first metric of the first portion of the cardiac signal recording, and determine a second metric of the second portion of the cardiac signal recording.

67. The computer readable medium of claim 66 wherein the executable instructions further cause the processor to compare the first metric to the second metric.

68. A medical device system comprising:

(a) a stimulating element for stimulating during a stimulation event time period to treat a neurological disorder;

(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 stimulating element and the cardiac monitoring element, the one or more processors configured to;

(i) determine at least one reference point for the stimulation event time period by evaluation of a stimulation state indicating stimulation by the stimulating element;

(ii) receive a recording of the cardiac signal; and

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