Dynamic cranial nerve stimulation based on brain state determination from cardiac data

• US 8,849,409 B2
• Filed: 03/03/2013
• Issued: 09/30/2014
• Est. Priority Date: 10/24/2008
• Status: Active Grant

• Current Assignee: Cyberonics, Inc, Flint Hills Scientific, LLC
• Original Assignee: Cyberonics, Inc, Flint Hills Scientific, LLC
• Inventors: Colborn, John C., Frei, Mark G., Osorio, Ivan
• Primary Examiner(s): MANUEL, GEORGE C
• Application Number:
  US13/783,393
• Publication Number:
  US 20130204144A1
• Time in Patent Office: 576 Days
• Field of Search: 607/45
• US Class Current: 607/45
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61N 1/36082 Cognitive or psychiatric applications, e.g. dementia or Alzheimer's disease
• CPC Class Codes: A61N 1/36114 Cardiac control, e.g. by vagal stimulation stimulating the heart A61N1/362

Abstract

A method of treating a medical condition in a patient using an implantable medical device, comprising providing an electrical signal generator; providing at least a first electrode operatively coupled to the electrical signal generator and to a vagus nerve of the patient; sensing cardiac data of the patient; determining at least a first cardiac parameter based upon said cardiac data; setting at least a first value; declaring an unstable brain state of a patient from said at least a first cardiac parameter and said at least a first value; and adjusting the at least a first value. Also, a computer readable program storage device encoded with instructions that, when executed by a computer, performs the method. In addition, the implantable medical device used in the method.

Claims

1. An medical device comprising:

a cardiac data sensing module operable to sense cardiac data;

a value setting module operable to set a first cardiac threshold value and dynamically adjust the first cardiac threshold value based upon sensed cardiac data from the cardiac sensing module;

a cardiac module operable to determine a first cardiac parameter based upon sensed cardiac data from the cardiac sensing module;

an unstable brain state declaration module operable to declare a seizure when the first cardiac parameter exceeds the first cardiac threshold value.

2. The medical device of claim 1, wherein:

the value setting module is operable to set a second cardiac threshold value and dynamically adjust the second cardiac threshold value based upon sensed cardiac data from the cardiac data sensing module;

the cardiac module is operable to determine a second cardiac parameter based upon sensed cardiac data; and

the unstable brain state declaration module is further operable to declare a seizure when the second cardiac parameter exceeds the second cardiac threshold value.

3. The medical device of claim 1, further comprising:

a non-cardiac data sensing module operable to sense non-cardiac data;

the value setting module operable to set a first non-cardiac threshold value and dynamically adjust the first non-cardiac threshold value based upon sensed non-cardiac data from the non-cardiac sensing module;

a non-cardiac module operable to determine a first non-cardiac parameter based upon sensed non-cardiac data from the non-cardiac data sensing module; and

the unstable brain state declaration module operable to declare an a seizure when the first non-cardiac parameter exceeds the first non-cardiac threshold value.

4. The medical device of claim 3, wherein:

the value setting module is further operable to apply a weighting factor to the first cardiac threshold value and the first non-cardiac threshold value; and

the unstable brain state declaration module is operable to utilize the weighted first cardiac threshold value and the first non-cardiac threshold value in declaring a seizure.

5. The medical device of claim 3, wherein the first non-cardiac parameter is selected from the group comprising:

an activity level;

an output of an accelerometer;

a catamenial cycle;

a time of day;

an indicator of a sleep state;

an inclination of a body;

a pupil dilation;

a body temperature;

a blood pressure; and

an electroencephalogram (EEG).

6. The medical device of claim 1, wherein the value setting module sets the first cardiac threshold value in response to a user request to set the first cardiac threshold value.

7. The medical device of claim 1, wherein the value setting module adjusts the first cardiac threshold value in response to a user request to adjust the first cardiac threshold value.

8. The medical device of claim 1, wherein the value setting module is operable to adjust the first cardiac threshold value to render the unstable brain state declaration module more likely to declare a seizure.

9. The medical device of claim 1, wherein the value setting module is operable to adjust the first cardiac threshold value to render the unstable brain state declaration module less likely to declare a seizure.

10. The medical device of claim 1, wherein the first cardiac parameter is selected from the group comprising:

an instantaneous heart rate;

a moving average heart rate over a predetermined time period;

a ratio of a first moving average heart rate over a first predetermined time period and a second moving average heart rate over a second predetermined time period;

a rate of change of a heart rate;

an elevation of an instantaneous heart rate above a baseline heart rate;

a duration of an elevation of a heart rate above a baseline heart rate;

a depression of a heart rate below a baseline heart;

a duration of an elevation of a first moving average heart rate over a second moving average heart rate;

an R-R interval;

a PR segment interval;

a PQ segment interval;

a QRS interval;

an ST segment interval;

a statistical analysis heart parameter;

a spectral analysis heart parameter;

a fractal analysis heart parameter;

an interbeat interval;

an amplitude or a magnitude of a P wave, Q wave, R wave, S wave, T wave, U wave;

a change in amplitude or a magnitude of a P wave, Q wave, R wave, S wave, T wave, U wave; and

a rate of change an amplitude or magnitude of a P wave, Q wave, R wave, S wave, T wave, U wave.

11. The medical device of claim 1, further comprising a memory that stores a timestamp associated with a declaration of a seizure.

12. The medical device of claim 11, wherein the value setting module is further configured to adjust a threshold value based upon the timestamp at which a seizure is declared.

13. The medical device of claim 11, wherein the value setting module is further configured to:

perform an analysis of a log of times at which a seizure was declared to determine a first period when an increased frequency of seizure declarations are likely to occur; and

adjust the first cardiac threshold value to render the unstable brain state declaration module more likely to declare a seizure during the first period.

14. The medical device of claim 1, wherein the medical device comprises an implantable medical device (IMD).

15. A method of declaring a seizure using a medical device, comprising:

sensing cardiac data;

setting a first cardiac threshold value based upon the sensed cardiac data;

dynamically adjusting the first cardiac threshold value based upon the sensed cardiac data;

determining a first cardiac parameter based upon the sensed cardiac data; and

declaring a seizure in response to the first cardiac parameter exceeding the first cardiac threshold value.

16. The method of claim 15, further comprising:

setting a second cardiac threshold value based upon the sensed cardiac data;

dynamically adjusting the second cardiac threshold value based upon the sensed cardiac data;

determining a second cardiac parameter based upon the sensed cardiac data; and

declaring a seizure in response to the second cardiac parameter satisfying the second cardiac threshold value.

17. The method of claim 16, further comprising:

applying a weighting factor to the first cardiac threshold value and the second cardiac threshold value; and

utilizing the weighted first cardiac threshold value and the weighted second cardiac threshold value in declaring seizure.

18. The method of claim 15, further comprising storing a timestamp associated with declaring a seizure.

19. The method of claim 18, further comprising adjusting a threshold value based upon the timestamp at which a seizure is declared.

20. The method of claim 18, further comprising:

performing an analysis of a log of times at which a seizure was declared to determine a first period when an increased frequency of seizure declarations are likely to occur; and

adjusting the first cardiac threshold value to render the unstable brain state declaration module more likely to declare a seizure during the first period.