Systems and methods for avoiding neural stimulation habituation

Abstract

An embodiment relates to a method for delivering a vagal stimulation therapy to a vagus nerve, including delivering a neural stimulation signal to non-selectively stimulate both afferent axons and efferent axons in the vagus nerve according to a predetermined schedule for the vagal stimulation therapy, and selecting a value for at least one parameter for the predetermined schedule for the vagal stimulation therapy to control the neural stimulation therapy to avoid physiological habituation to the vagal stimulation therapy. The parameter(s) include at least one parameter selected from the group of parameters consisting of a predetermined therapy duration parameter for a predetermined therapy period, and a predetermined intermittent neural stimulation parameter associated with on/off timing for the intermittent neural stimulation parameter.

1 . (canceled) 
     
     
         2 . A method, comprising:
 providing an implantable neurostimulator comprising a sensor and a pulse generator configured to deliver electrical therapeutic stimulation to a vagus nerve of a patient;   storing neural stimulation parameters in a memory;   delivering neural stimulation to the vagus nerve at a first, lower intensity;   monitoring a physiological state of the patient via the sensor; and   upon sensing the physiological state, delivering the neural stimulation to the vagus nerve at a second, higher intensity.   
     
     
         3 . The method of  claim 2 , wherein the neural stimulation is delivered according to a daily schedule. 
     
     
         4 . The method of  claim 2 , further comprising, delivering electrical therapy for a tachyarrhythmia. 
     
     
         5 . The method of  claim 2 , wherein the sensor comprises a heart rate sensor, and the physiological state includes an elevated heart rate. 
     
     
         6 . The method of  claim 2 , wherein the sensor comprises a respiration sensor. 
     
     
         7 . The method of  claim 2 , further comprising changing a period of time for delivering the neurostimulator. 
     
     
         8 . The method of  claim 2 , wherein the delivering the neural stimulation to the vagus nerve at a second, higher intensity includes changing an output current, a duty cycle, a frequency, and a pulse width. 
     
     
         9 . The method of  claim 2 , wherein the monitoring the physiological state of the patient via the sensor includes monitoring cardiac activity to sense the physiological state. 
     
     
         10 . The method of  claim 9 , wherein the neural stimulation is delivered according to a daily schedule. 
     
     
         11 . The method of  claim 9 , wherein the neural stimulation is delivered with different intensities during a day. 
     
     
         12 . The method of  claim 9 , wherein monitoring cardiac activity includes monitoring cardiac activity for tachycardia. 
     
     
         13 . The method of  claim 12 , wherein raising the intensity of the vagal nerve stimulation reduces heart rate. 
     
     
         14 . The method of  claim 9 , wherein monitoring the physiological state further includes monitoring respiration. 
     
     
         15 . A method of operating an implantable medical device (IMD) comprising a neurostimulator coupled to an electrode assembly, said neurostimulator adapted to deliver a stimulation signal at a plurality of intensity parameter levels, said method comprising:
 monitoring a heart rate of a patient implanted with the IMD;   delivering to the patient a first set of stimulation signals at a first frequency to cause a heart rate below a threshold;   responsive to detecting increased heart rate, delivering to the patient at a second frequency different than the first frequency to increase the intensity parameter level for subsequent stimulation signals.   
     
     
         16 . The method of  claim 15 , further comprising activating the IMD to chronically deliver the stimulation signal having the first intensity parameter level. 
     
     
         17 . The method of  claim 15 , further comprising increasing at least one of pulse width, duty cycle or amplitude for sensed elevated heart rate. 
     
     
         18 . The method of  claim 15 , further comprising, prior to delivering the first set of stimulation signals, further comprising gradually increasing intensity of the neural stimulation. 
     
     
         19 . The method of  claim 15 , further comprising delivering the stimulation signals to a vagus nerve of the patient. 
     
     
         20 . The method of  claim 15 , wherein the second frequency is higher than the first frequency. 
     
     
         21 . The method of  claim 15 , wherein the monitoring heart rate includes monitoring for tachycardia.