VAGUS NERVE STIMULATION METHOD

• US 20070233192A1
• Filed: 03/29/2007
• Published: 10/04/2007
• Est. Priority Date: 03/29/2006
• Status: Active Grant

• Current Assignee: Catholic Healthcare West (CommonSpirit Health (Illinois))
• Original Assignee: Catholic Healthcare West (CommonSpirit Health (Illinois))
• Inventors: Craig, Arthur D.
• Granted Patent: US 8,150,508 B2
• Time in Patent Office: Days
• US Class Current: 607/2
• 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 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/353 Detecting P-waves
• CPC Class Codes: A61B 5/355 Detecting T-waves
• 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 1/0551 Spinal or peripheral nerve electrodes
• CPC Class Codes: A61N 1/3605 Implantable neurostimulators for stimulating central or peripheral nerve system
• CPC Class Codes: A61N 1/36053 adapted for vagal stimulation A61N1/36114 takes precedence
• 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 1/36114 Cardiac control, e.g. by vagal stimulation stimulating the heart A61N1/362
• CPC Class Codes: A61N 1/36139 with automatic adjustment
• CPC Class Codes: A61N 1/36178 Burst or pulse train parameters

Abstract

An implanted electrical signal generator delivers a novel exogenous electrical signal to a vagus nerve of a patient. The vagus nerve conducts action potentials originating in the heart and lungs to various structures of the brain, thereby eliciting a vagal evoked potential in those structures. The exogenous electrical signal simulates and/or augments the endogenous afferent activity originating from the heart and/or lungs of the patient, thereby enhancing the vagal evoked potential in the various structures of the brain. The exogenous electrical signal includes a series of electrical pulses organized or patterned into a series of microbursts including 2 to 20 pulses each. No pulses are sent between the microbursts. Each of the microbursts may be synchronized with the QRS wave portion of an ECG. The enhanced vagal evoked potential in the various structures of the brain may be used to treat various medical conditions including epilepsy and depression.

Claims

1. A method of treating a medical condition in a patient having a vagus nerve and a heart that generates a cardiac signal having a QRS wave portion, comprising:

detecting a portion of the QRS wave portion of the patient'"'"'s cardiac signal;

after detecting the portion of the QRS wave portion, generating a microburst comprising 2 to 20 electrical pulses; and

delivering the microburst to the vagus nerve of the patient.

2. The method of claim 1, further comprising, generating additional electrical pulses after detecting another QRS wave portion of the cardiac signal.

3. The method of claim 1, further comprising, after detecting the portion of the QRS wave portion, waiting a predetermined delay period before generating the microburst.

4. The method of claim 1, further comprising, after detecting the portion of the QRS wave portion, waiting less than about 1000 milliseconds before generating a second microburst comprising from 2 to 20 electrical pulses.

5. The method of claim 1, wherein the electrical pulses of the microburst are generated in a series having a first pulse and a last pulse, each pulse other than the last pulse being separated from a successor pulse in the series by an interpulse interval having a duration, the duration of the interpulse interval increasing along the series from the first pulse to the last pulse.

6. The method of claim 1, wherein the electrical pulses have a pulse width of from about 50 microseconds to about 1000 microseconds, and have a pulse current amplitude of from about 0.25 mA to about 8 mA.

7. The method of claim 1, wherein the electrical pulses of the microburst are generated in a series having a last pulse, each pulse other than the last pulse of the series being separated from a successor pulse in the series by an interpulse interval, each interpulse interval being less than about 40 milliseconds.

8. The method of claim 1, wherein the electrical pulses of the microburst are generated in a series having a last pulse, each pulse other than the last pulse of the series being separated from a successor pulse in the series by an interpulse interval, each interpulse interval having been determined empirically for the patient.

9. The method of claim 1, wherein the electrical pulses of the microburst are generated in a series having a last pulse, each pulse other than the last pulse of the series being separated from a successor pulse in the series by an interpulse interval of about 3 milliseconds to about 10 milliseconds.

10. The method of claim 1, wherein the patient is breathing and has a heart with a heart rate variability, the method further comprising restricting the patient'"'"'s breathing to increase the heart rate variability.

11. An exogenous electrical signal adapted to be delivered to a vagus nerve of a patient having a brain and a medical condition, the vagus nerve evoking a vagal evoked potential in the brain, the exogenous electrical signal comprising a series of microbursts, each microburst in the series comprising from 2 to 20 electrical pulses, wherein the exogenous electrical signal is adapted to treat the medical condition by enhancing the vagal evoked potential in the brain.

12. An implantable device configured to apply the signal of claim 11.

13. An exogenous electrical signal adapted to be delivered to a vagus nerve of a patient having a brain and a medical condition, the vagus nerve evoking a vagal evoked potential in the brain, the exogenous electrical signal comprising a series of microbursts, each microburst having a duration less than about one second, wherein the exogenous electrical signal is adapted to treat the medical condition by enhancing the vagal evoked potential in the brain.

14. An implantable device configured to apply the signal of claim 13.

15. An exogenous electrical signal adapted to be delivered to a vagus nerve of a patient having a brain, a medical condition, and a heart operating in a cardiac cycle with an R wave portion, the vagus nerve evoking a vagal evoked potential in the brain, the exogenous electrical signal adapted to treat the medical condition by enhancing the vagal evoked potential in the brain, the signal comprising:

a series of microbursts, each microburst comprising 2 to 20 electrical pulses, and each of the microbursts occurring after a selected R wave portion of the cardiac cycle.

16. The signal of claim 15, wherein each R wave portion is separated from a successive R wave portion by an R-R interval, each R-R interval has a duration and a previous R-R interval preceding it, and each of the microbursts occurs after an R-R interval having a duration that is shorter than the duration of the previous R-R interval.

17. The signal of claim 15, wherein the pulses of the microbursts are spaced to simulate endogenous afferent activity occurring at a particular time in the cardiac cycle.

18. The signal of claim 15, wherein each of the microbursts is delayed relative to the selected R wave portion to simulate endogenous afferent activity occurring at a particular time in the cardiac cycle.

19. The signal of claim 15, wherein each of the microbursts occurs less than about 1000 milliseconds after the selected R wave portion.

20. An exogenous electrical signal adapted to be delivered to a vagus nerve of a patient having a brain, lungs, a medical condition, and a heart with a cardiac signal comprising an inspiration portion corresponding to an inspiration of air by the lungs and an expiration portion corresponding to an expiration of air by the lungs, the inspiration portion having a series of R wave portions, the expiration portion having a series of R wave portions, the vagus nerve evoking a vagal evoked potential in the brain, the exogenous electrical signal adapted to be delivered to the vagus nerve to treat the condition or disorder of the nervous system by enhancing the vagal evoked potential in the brain, the signal comprising:

a series of microbursts, each microburst in the series comprising from 2 to 20 electrical pulses, each of the microbursts being delivered to the vagus nerve in response to a selected R wave portion of the inspiration portion of the cardiac signal, and none of the microbursts being delivered in response to the R wave portions of the expiration portion of the cardiac signal.

21. The signal of claim 20, wherein the pulses of the microbursts are spaced to simulate endogenous afferent activity occurring at a particular time in the cardiac signal.

22. The signal of claim 20, wherein the pulses of the microbursts are spaced to simulate endogenous afferent activity occurring at a particular time during inspiration of air by the lungs.

23. The signal of claim 20, wherein the microbursts are spaced to simulate endogenous afferent activity occurring at a particular time in the cardiac signal.

24. The signal of claim 20, wherein the microbursts are spaced to simulate endogenous afferent activity occurring at a particular time during inspiration of air by the lungs.

25. A method of customizing an exogenous electrical signal adapted to be delivered to a vagus nerve of a patient having a brain and a medical condition, and to elicit a desired vagal evoked potential in a selected structure of the brain associated with the medical condition, the method comprising:

determining a value of a signal parameter;

generating an electrical signal according to the signal parameter, the electrical signal comprising a series of microbursts, each microburst comprising a series of from 2 to 20 electrical pulses;

delivering the electrical signal to the vagus nerve of the patient;

analyzing an EEG of the patient'"'"'s brain created during the delivery of the electrical signal to the vagus nerve of the patient to determine the vagal evoked potential observed in the selected structure of the brain; and

modifying the value of the signal parameter based on the vagal evoked potential observed in the selected structure of the brain to modify the vagal evoked potential observed therein.

26. The method of claim 25, wherein the selected structure of the brain includes a region selected from the group consisting of the thalamus, the striatum, the insular cortex, and combinations thereof.

27. The method of claim 25, wherein the signal parameter is a parameter selected from the group consisting of a pulse width, a pulse frequency, an interpulse interval between two of the pulses of the microburst, a frequency of the microbursts, a number of microbursts of the series of microburst, a duration of the electrical signal, a number of pulses in the microbursts, and combinations thereof.

28. The method of claim 25, wherein the patient has a heart that generates a series of QRS waves, each of the microbursts is delivered to the vagus nerve after a selected QRS wave of the series of QRS waves, and the signal parameter comprises a delay period between each microburst and the selected QRS wave.

29. The method of claim 25, wherein the patient has a heart that generates a series of QRS waves, and the signal parameter comprises a selected QRS wave of the series of QRS waves to precede each microburst of the series of microbursts.

30. A method of treating a medical condition in a patient having a vagus nerve and a heart that generates a cardiac signal having a QRS wave portion, comprising:

detecting the QRS wave portion of the cardiac signal;

generating a microburst comprising a series electrical pulses separated by an interpulse interval, the sum of the interpulse intervals separating the pulses being less than 60 milliseconds; and

delivering the microburst to the vagus nerve of the patient.

31. The method of claim 30, further comprising, after detecting the QRS wave portion, waiting a predetermined delay period before applying the microburst to the vagus nerve.

32. The method of claim 30, further comprising, after detecting the QRS wave portion, waiting less than about 500 milliseconds before applying the microburst to the vagus nerve.

33. The method of claim 30, wherein the electrical pulses have a pulse width of from about 50 microseconds to about 1000 microseconds.

34. The method of claim 30, wherein the electrical pulses of the microburst are generated in a series having a last pulse, each pulse other than the last pulse of the series being separated from a successor pulse in the series by an interpulse interval, each interpulse interval being less than about 40 milliseconds.

35. The method of claim 30, wherein each of the interpulse intervals is determined empirically for the patient.

36. The method of claim 30, wherein each of the interpulse intervals is about 3 milliseconds to about 12 milliseconds.

37. The method of claim 30, wherein the patient is breathing and has a heart with a heart rate variability, the method further comprising restricting the patient'"'"'s breathing to increase the heart rate variability.

38. A system for treating a medical condition in a patient having a vagus nerve and a heart that generates a cardiac signal having a QRS wave portion, the system comprising:

a sensor configured to detect a portion of the QRS wave portion of the cardiac signal;

an electrical signal generator configured to generate a microburst after the detection of the portion of the QRS wave portion by the sensor, the microburst having a duration of less than about one second; and

an electrode in electrical communication with the vagus nerve, the electrode being configured to deliver the microburst to the vagus nerve of the patient.

39. The system of claim 38, wherein the duration of the microburst is less than about 100 milliseconds.

40. The system of claim 38, wherein the electrical signal generator is configured to wait a predetermined delay period after detection of the portion of the QRS wave portion wave before applying the microburst.

41. The system of claim 38, wherein the microburst comprises a series of electrical pulses having a last pulse, each pulse other than the last pulse of the series being separated from a successor pulse in the series by an interpulse interval of about 3 milliseconds to about 10 milliseconds.

42. A computer readable medium having computer executable components for detecting a QRS wave portion of a cardiac cycle;

generating a microburst having 2 to 20 electrical pulses; and

delivering the microburst via an electrode to the vagus nerve of a patient in response to the detection of the QRS wave portion of a cardiac cycle.

43. The computer readable medium of claim 42, wherein the electrical pulses of the microburst are generated in a series having a last pulse, each pulse other than the last pulse being separated from a successor pulse in the series by an interpulse interval having a duration, the computer readable medium further comprising computer executable components for determining the duration of each of the interpulse intervals.

44. A method of treating a medical condition in a patient having a vagus nerve, comprising allowing the patient to manually trigger generation of an exogenous electrical signal comprising a microburst having a duration of less than about one second;

and delivering the exogenous electrical signal to the vagus nerve of the patient.

45. The method of claim 45, wherein the patient has a heart that generates a cardiac signal having a QRS wave portion, the method further comprising, detecting the QRS wave portion of the cardiac signal and delivering the microburst of the exogenous electrical signal to the vagus nerve of the patient in response to detection of the QRS wave portion.

46. The method of claim 45, wherein the patient is performing paced breathing before triggering the exogenous electrical signal.