Vagus nerve stimulation method

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.

1 . An implantable medical device for treating a medical condition in a patient, the implantable medical device comprising:
 one or more processors configured to determine a detection of at least a portion of a respiratory cycle of the patient where the detection of the respiratory cycle of the patient includes at least one of an inspiration of breath determination and an expiration of breath determination;   wherein in response to the detection of the portion of the respiratory cycle of the patient, the one or more processors are configured to apply a pulsed electrical signal to a vagus nerve of the patient where the pulsed electrical signal includes a plurality of microbursts, wherein the one or more processors are configured to apply a microburst to the vagus nerve of the patient after a delay period following at least one of the inspiration of breath determination and the expiration of breath determination.   
     
     
         2 . The implantable medical device of  claim 1 , wherein a stimulation via the pulsed electrical signal is further based on one or more R-waves of the respiratory cycle. 
     
     
         3 . The implantable medical device of  claim 1 , wherein a first microburst is separated from a second microburst by an interburst period. 
     
     
         4 . The implantable medical device of  claim 3 , wherein the interburst period is at least 100 milliseconds. 
     
     
         5 . The implantable medical device of  claim 3 , wherein the interburst period is in a range of about 1 millisecond to about 20 milliseconds. 
     
     
         6 . The implantable medical device of  claim 1 , wherein at least one microburst includes 2 to 20 pulses. 
     
     
         7 . The implantable medical device of  claim 1 , wherein the delay period is about 0.5 seconds to about 1.0 second after at least one of the inspiration of breath determination and the expiration of breath determination. 
     
     
         8 . The implantable medical device of  claim 1 , wherein at least one microburst includes 2 to 6 pulses. 
     
     
         9 . A method of treating a medical condition in a patient, the method comprising:
 determining via the one or more processors a detection a portion of a respiratory cycle of the patient where the detection of the respiratory cycle of the patient includes an inspiration of breath determination;   wherein in response to the detection of the portion of the respiratory cycle of the patient, the method includes applying a pulsed electrical signal to a vagus nerve of the patient where the pulsed electrical signal includes a plurality of microbursts; and   applying a microburst to the vagus nerve of the patient after a delay period following the inspiration of breath determination.   
     
     
         10 . The method of  claim 9 , wherein a stimulation via the pulsed electrical signal is further based on one or more R-waves of the respiratory cycle. 
     
     
         11 . The method of  claim 9 , wherein a first microburst is separated from a second microburst by an interburst period. 
     
     
         12 . The method of  claim 11 , wherein the interburst period is at least 100 milliseconds. 
     
     
         13 . The method of  claim 11 , wherein the interburst period is in a range of about 1 millisecond to about 20 milliseconds. 
     
     
         14 . The method of  claim 9 , wherein at least one microburst includes 2 to 20 pulses. 
     
     
         15 . The method of  claim 9 , wherein the delay period is about 0.5 seconds to about 1.0 second after the inspiration of breath determination. 
     
     
         16 . A medical system for treating a medical condition in a patient, the medical system comprising:
 one or more processors configured to determine a detection of an R-wave and a portion of a respiratory cycle of the patient where the detection of the respiratory cycle of the patient includes an inspiration of breath determination;   the one or more processors configured to apply a pulsed electrical signal to a vagus nerve of the patient in response to a second detection of the portion of the respiratory cycle of the patient where the pulsed electrical signal includes a plurality of microburst;
 the one or more processors configured to apply a microburst to the vagus nerve of the patient after a delay period following the inspiration of breath determination where the delay period is about 0.5 seconds to about 1.0 seconds after the inspiration of breath determination and within 50 milliseconds following the R-wave; 
 the one or more medical devices configured to determine a vagal evoked potential based on at least one of the applied pulsed electrical signal and the applied microburst; and 
 the one or more medical devices configured to modify the vagal evoked potential via modifying at least one of the applied pulsed electrical signal and the applied microburst. 
   
     
     
         17 . The medical system of  claim 16 , wherein a stimulation via the pulsed electrical signal is further based on one or more R-waves of the respiratory cycle. 
     
     
         18 . The medical system of  claim 16 , wherein a first microburst is separated from a second microburst by an interburst period. 
     
     
         19 . The medical system of  claim 18 , wherein the interburst period is at least 100 milliseconds. 
     
     
         20 . The medical system of  claim 18 , wherein the interburst period is in a range of about 1 millisecond to about 20 milliseconds.