SYSTEMS AND METHODS FOR USING ELECTRICAL IMPEDANCE FOR NEURO CARDIAC THERAPY

• US 20120172742A1
• Filed: 12/01/2011
• Published: 07/05/2012
• Est. Priority Date: 12/29/2010
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Arcot-Krishnamurthy, Shantha, Zhang, Yi, Hatlestad, John D.
• Granted Patent: US 9,393,415 B2
• Time in Patent Office: Days
• US Class Current: 600/536
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61N 1/36053 adapted for vagal stimulation A61N1/36114 takes precedence
• CPC Class Codes: A61N 1/36117 for treating hypertension
• CPC Class Codes: A61N 1/3614 based on impedance measurement
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance

Abstract

A device embodiment is configured to deliver vagal stimulation therapy (VST) to a vagus nerve of a patient. The device embodiment includes a neural stimulator, an implantable impedance sensor and an impedance analyzer. The neural stimulator is configured to deliver the VST to the vagus nerve in a cervical region of the patient. The implantable impedance sensor is configured to detect impedance changes in a cervical region of the patient caused by laryngeal vibrations. The impedance sensor is configured to generate sensed impedance values. The impedance analyzer is configured to analyze the sensed impedance values generated by the sensor. The analyzer is configured to detect laryngeal vibrations or cough from the sensed impedance values.

Claims

1. A method, comprising:

delivering a vagal stimulation therapy (VST) to a vagus nerve of a patient;

detecting laryngeal vibrations to determine whether the VST is capturing the vagus nerve, wherein detecting laryngeal vibrations includes;

sensing impedance in a cervical region of a patient to sense changes in impedance characteristics caused by laryngeal vibrations, wherein sensing impedance includes sensing impedance a plurality of times to provide a plurality of sensed impedance values; and

analyzing a plurality of the sensed impedance values to confirm the laryngeal vibrations.

2. The method of claim 1, wherein delivering the VST includes delivering the VST using an electrode in a blood vessel;

and sensing impedance includes sensing impedance using the electrode in the blood vessel.

3. The method of claim 2, wherein the blood vessel is an internal jugular vein.

4. The method of claim 1, further comprising detecting whether the VST is causing cough, including analyzing a plurality of the sensed impedance values to confirm the cough.

5. The method of claim 1, wherein delivering VST includes delivering a neuro cardio therapy (NCT) to treat a cardiovascular disease, wherein delivering NCT includes

delivering NCT as a heart failure therapy or delivering NCT as a hypertension therapy.

6. The method of claim 1, wherein analyzing the plurality of the sensed impedance values includes detecting a change in absolute impedance values, detecting a change in mean of the sensed impedance values, or detecting a change in variability of the sensed impedance values.

7. The method of claim 6, wherein analyzing the plurality of the sensed impedance values includes analyzing the variability of the plurality of the sensed impedance, and analyzing the variability of the plurality of the sensed impedance includes determining a standard deviation or an Inter-Percentile Range of the sensed impedance.

8. A method, comprising:

performing a threshold determination routine for delivering a vagal stimulation therapy (VST) to a vagus nerve of a patient, wherein performing the threshold determination routine includes;

delivering VST to the vagus nerve;

changing an intensity of the VST in a plurality of intensity steps; and

at each intensity step, monitoring for laryngeal vibrations, wherein monitoring for laryngeal vibrations includes;

sensing impedance in a cervical region of a patient to sense changes in impedance characteristics caused by laryngeal vibrations, wherein sensing impedance includes sensing impedance a plurality of times to provide a plurality of sensed impedance values; and

analyzing a plurality of the sensed impedance values to confirm the laryngeal vibrations.

9. The method of claim 8, wherein analyzing the plurality of the sensed impedance values includes detecting a change in absolute impedance values that indicates laryngeal vibrations, detecting a mean of the sensed impedance values that indicates laryngeal vibrations, or detecting variability of the sensed impedance values that indicates laryngeal vibrations.

10. The method of claim 8, further comprising:

delivering the VST at a VST intensity level; and

intermittently performing a threshold verification routine, including;

sensing impedance a plurality of times each time the threshold verification routine is performed to provide a plurality of sensed impedance values;

analyzing the plurality of the sensed impedance values each time the threshold verification routine is performed to confirm the laryngeal vibrations at the VST intensity level; and

recording a result of the analysis.

11. The method of claim 8, further comprising:

delivering the VST at a VST intensity level; and

intermittently performing a threshold verification routine, including;

sensing impedance a plurality of times each time the threshold verification routine is performed to provide a plurality of sensed impedance values;

analyzing the plurality of the sensed impedance values each time the threshold verification routine is performed to confirm the laryngeal vibrations at the VST intensity level; and

notifying a patient or physician if laryngeal vibrations are not confirmed at the VST intensity level.

12. The method of claim 8, further comprising:

delivering the VST at a VST intensity level; and

intermittently performing a threshold verification routine, including;

sensing impedance a plurality of times each time the threshold verification routine is performed to provide a plurality of impedance values;

analyzing the plurality of the sensed impedance values each time the threshold verification routine is performed to confirm the laryngeal vibrations at the VST intensity level; and

if laryngeal vibrations are not confirmed at the VST intensity level, performing the threshold verification routine to identify an intensity step where laryngeal vibrations are confirmed.

13. The method of claim 8, comprising performing a cough detection routine for delivering VST after laryngeal vibrations are found, wherein performing the cough detection routine includes:

sensing impedance to provide a plurality of sensed impedance values for each of a plurality of intensity steps higher than the intensity step at which laryngeal vibrations are found; and

analyzing the plurality of sensed impedance values for each of a plurality of intensity steps higher than the intensity step at which laryngeal vibrations are found, wherein a step increase in absolute value, mean or variability of sensed impedance from a laryngeal vibration level indicates cough.

14. The method of claim 8, wherein analyzing the plurality of the sensed impedance values includes determining a standard deviation or an Inter-Percentile Range of the variability of the sensed impedance.

15. A device for delivering vagal stimulation therapy (VST) to a vagus nerve of a patient, comprising:

a neural stimulator configured to deliver the VST to the vagus nerve in a cervical region of the patient;

an implantable impedance sensor configured for use in detecting changes in impedance characteristics in a cervical region of the patient caused by laryngeal vibrations, wherein the impedance sensor is configured to generate sensed impedance values; and

an impedance analyzer configured to analyze the sensed impedance values generated by the sensor, wherein the analyzer is configured to detect laryngeal vibrations or cough from the sensed impedance values.

16. The device of claim 15, further comprising a controller configured to control an intensity of the VST delivered by the neural stimulator, and perform a threshold verification routine, wherein in performing the threshold verification routine, the controller is configured to:

change the intensity of the VST in a plurality of intensity steps; and

monitor for laryngeal vibrations at each intensity step, wherein in monitoring for laryngeal vibrations, the controller is configured to;

receive a plurality of sensed impedance values from the impedance sensor at each intensity step; and

analyze the plurality of sensed impedance values for each intensity step to determine if the VST is causing laryngeal vibrations.

17. The device of claim 16, wherein the controller is configured to detect laryngeal vibrations from these sensed impedance values, configured to detect cough or muscle stimulation from these sensed impedance values, and configured to adjust the intensity of the VST in response to an output from the impedance analyzer.

18. The device of claim 15, wherein the controller is further configured to adjust the intensity of the VST in response to an output from the impedance analyzer.

19. The device of claim 15, further comprising a controller configured to control an intensity of the VST delivered by the neural stimulator, and intermittently perform a threshold detection routine, wherein in performing the threshold detection routine, the controller is configured to:

receive a plurality of sensed impedance values from the impedance sensor each time the threshold verification routine is performed;

analyze the sensed impedance values each time the threshold verification routine is performed to confirm the laryngeal vibrations at the VST intensity level; and

if laryngeal vibrations are not confirmed at the VST intensity level, perform the threshold verification routine to identify an intensity step where laryngeal vibrations are confirmed, or notify the patient or a physician if laryngeal vibration is not confirmed at a highest VST intensity level that the device is configured to deliver.

20. The device of claim 15, wherein the implantable impedance sensor includes:

an electrode on a lead configured to be implanted in a carotid sheath of the patient;

or

an electrode on a lead configured to be implanted in an internal jugular vein of the patient.

21. The device of claim 19, wherein the neural stimulator is configured to deliver VST to the vagus nerve from the internal jugular vein.

22. A method for detecting laryngeal vibrations, comprising:

sensing impedance in a cervical region of a patient to sense changes in impedance characteristics caused by laryngeal vibrations, wherein sensing impedance includes sensing impedance a plurality of times to provide the plurality of sensed impedance values; and

analyzing a plurality of the sensed impedance values to confirm the laryngeal vibrations, wherein sensing impedance includes;

sensing impedance changes in or near a carotid sheath;

or

sensing impedance using a lead in an internal jugular vein.

23. A method for detecting cough, comprising:

sensing impedance in a cervical region of a patient to sense changes in impedance characteristics caused by cough, wherein sensing impedance includes sensing impedance a plurality of times to provide a plurality of sensed impedance values; and

analyzing the plurality of the sensed impedance values to confirm the cough, wherein sensing impedance includes;

sensing impedance changes in or near a carotid sheath;

or

sensing impedance using a lead in an internal jugular vein.