Automatic baroreflex modulation based on cardiac activity

Abstract

An aspect of the present subject matter relates to a system for providing baroreflex stimulation. An embodiment of the system comprises a cardiac activity monitor to sense cardiac activity and provide a signal indicative of the cardiac activity, and a baroreflex stimulator. The stimulator includes a pulse generator and a modulator. The pulse generator provides a baroreflex stimulation signal adapted to provide a baroreflex therapy. The modulator receives the signal indicative of the cardiac activity and modulates the baroreflex stimulation signal based on the signal indicative of the cardiac activity to change the baroreflex therapy from a first baroreflex therapy to a second baroreflex therapy. Other aspects are provided herein.

1 . A system for providing baroreflex stimulation, comprising: 
 a cardiac activity monitor to sense cardiac activity and provide a signal indicative of the cardiac activity; and    a baroreflex stimulator, including: 
 a pulse generator to provide a baroreflex stimulation signal adapted to provide a baroreflex therapy; and  
 a modulator to receive the signal indicative of the cardiac activity and modulate the baroreflex stimulation signal based on the signal indicative of the cardiac activity to change the baroreflex therapy from a first baroreflex therapy to a second baroreflex therapy.  
   
   
   
       2 . The system of  claim 1 , wherein the baroreflex stimulation signal has an amplitude, and the modulator includes a modulator to modulate the amplitude based on the signal indicative of the cardiac activity.  
   
   
       3 . The system of  claim 1 , wherein the baroreflex stimulation signal has a frequency, and the modulator includes a modulator to modulate the frequency based on the signal indicative of the cardiac activity.  
   
   
       4 . The system of  claim 1 , wherein the baroreflex stimulation signal has a burst frequency, and the modulator includes a modulator to modulate the burst frequency based on the signal indicative of the cardiac activity.  
   
   
       5 . The system of  claim 1 , further comprising a waveform generator to produce baroreflex stimulation signals of a desired morphology, wherein the modulator includes a modulator to change the morphology of the baroreflex stimulation signal based on the signal indicative of the cardiac activity.  
   
   
       6 . The system of  claim 1 , wherein the cardiac activity monitor includes a heart rate sensor, and the signal indicative of the cardiac activity includes a heart rate signal.  
   
   
       7 . The system of  claim 1 , wherein the cardiac activity monitor includes a respiration monitor, and the signal indicative of the cardiac activity includes a respiration signal.  
   
   
       8 . The system of  claim 7 , wherein the respiration monitor includes a tidal volume monitor.  
   
   
       9 . The system of  claim 7 , wherein the respiration monitor includes a minute ventilation monitor.  
   
   
       10 . The system of  claim 1 , wherein the cardiac activity monitor includes an acceleration sensor, and the signal indicative of the cardiac activity includes an acceleration signal.  
   
   
       11 . The system of  claim 1 , wherein: 
 the cardiac activity monitor includes a combination of two or more of the following sensors: a heart rate sensor; a minute ventilation sensor; and an acceleration sensor; and    the signal indicative of the cardiac activity includes a composite of two or more of the following signals: a heart rate signal; a minute ventilation signal; and an acceleration signal.    
   
   
       12 . The system of  claim 1 , wherein the cardiac activity monitor includes a sensor to sense at least one pressure parameter, and the signal indicative of the cardiac activity includes a signal indicative of the at least one pressure parameter.  
   
   
       13 . The system of  claim 12 , wherein the at least one pressure parameter includes mean arterial pressure.  
   
   
       14 . The system of  claim 12 , wherein the at least one pressure parameter includes a pulse pressure.  
   
   
       15 . The system of  claim 12 , wherein the at least one pressure parameter includes an end systolic pressure.  
   
   
       16 . The system of  claim 12 , wherein the at least one pressure parameter includes an end diastolic pressure.  
   
   
       17 . The system of  claim 1 , wherein the cardiac activity monitor includes a stroke volume monitor, and the signal indicative of the cardiac activity includes a signal indicative of the stroke volume.  
   
   
       18 . The system of  claim 1 , wherein the cardiac activity monitor includes a monitor to measure at least one electrogram measurement, and the signal indicative of the cardiac activity includes a signal indicative of the at least one electrogram measurement.  
   
   
       19 . The system of  claim 1 , wherein the cardiac activity monitor includes a monitor to measure at least one electrocardiogram (ECG) measurement, and the signal indicative of the cardiac activity includes a signal indicative of the at least one ECG measurement.  
   
   
       20 . The system of  claim 1 , further comprising an implantable medical device, wherein the implantable medical device includes the cardiac activity monitor and the baroreflex stimulator.  
   
   
       21 . The system of  claim 1 , further comprising an implantable neural stimulator (NS) device and an implantable cardiac stimulator, wherein the implantable NS device includes the baroreflex stimulator and the implantable cardiac stimulator includes the cardiac activity monitor, and both the implantable cardiac stimulator and the implantable NS device include transceivers to wirelessly communicate with each other.  
   
   
       22 . The system of  claim 21 , wherein the transceivers include a telemetry coil.  
   
   
       23 . The system of  claim 1 , wherein the stimulator is implantable, the stimulator further comprising a lead adapted to be electrically connected to the pulse generator and to be fed through a right ventricle and into a pulmonary artery, the lead including the electrode, the electrode to be positioned in the pulmonary artery and to deliver the baroreflex stimulation signal to a baroreceptor site in the pulmonary artery.  
   
   
       24 . A baroreflex stimulator, comprising: 
 an implantable pulse generator to provide a baroreflex stimulation signal adapted to provide a baroreflex therapy; and    means for modulating the baroreflex stimulation signal based on a signal indicative of cardiac activity to change the baroreflex therapy from a first baroreflex therapy to a second baroreflex therapy.    
   
   
       25 . The baroreflex stimulator of  claim 24 , wherein the means for modulating the baroreflex stimulation signal includes means for modulating the baroreflex stimulation signal based on heart rate.  
   
   
       26 . The baroreflex stimulator of  claim 24 , wherein the means for modulating the baroreflex stimulation signal includes means for modulating the baroreflex stimulation signal based on respiration.  
   
   
       27 . The baroreflex stimulator of  claim 26 , wherein the means for modulating the baroreflex stimulation signal based on respiration includes means for modulating the baroreflex stimulation based on tidal volume.  
   
   
       28 . The baroreflex stimulator of  claim 26 , wherein the means for modulating the baroreflex stimulation signal based on respiration includes means for modulating the baroreflex stimulation based on minute ventilation.  
   
   
       29 . The baroreflex stimulator of  claim 24 , wherein the means for modulating the baroreflex stimulation signal includes means for modulating the baroreflex stimulation signal based on acceleration.  
   
   
       30 . The baroreflex stimulator of  claim 24 , wherein the stimulator is implantable, the stimulator further comprising a lead adapted to be electrically connected to the pulse generator, to be fed through a right ventricle and into a pulmonary artery, and to deliver the baroreflex stimulation signal to a baroreceptor site in the pulmonary artery.  
   
   
       31 . The baroreflex stimulator of  claim 24 , wherein the baroreflex stimulation signal has an amplitude, and the means for modulating the baroreflex stimulation signal includes means for adjusting the amplitude of the baroreflex stimulation signal.  
   
   
       32 . The baroreflex stimulator of  claim 24 , wherein the baroreflex stimulation signal has a frequency, and the means for modulating the baroreflex stimulation signal includes means for adjusting the frequency of the baroreflex stimulation signal.  
   
   
       33 . The baroreflex stimulator of  claim 24 , wherein the baroreflex stimulation signal has a duty cycle, and the means for modulating the baroreflex stimulation signal includes means for adjusting the duty cycle of the baroreflex stimulation signal.  
   
   
       34 . The baroreflex stimulator of  claim 24 , wherein the baroreflex stimulation signal has a morphology, and the means for modulating the baroreflex stimulation signal includes means for adjusting the morphology of the baroreflex stimulation signal.  
   
   
       35 . A method for operating an implantable medical device, comprising: 
 receiving a signal regarding an activity level; and    setting a baroreflex stimulation level for a baroreflex stimulator of the device based on the signal regarding the activity level.    
   
   
       36 . The method of  claim 35 , further comprising determining whether the activity level is rest or exercise, wherein setting a baroreflex stimulation level includes applying baroreflex stimulation during rest and withdrawing baroreflex stimulation during exercise.  
   
   
       37 . The method of  claim 35 , further comprising determining whether the activity level is a first activity level or a second activity level where the first activity level is higher than the second activity, wherein setting a baroreflex stimulation level includes setting a first baroreflex stimulation level when the activity level is determined to be the second activity level and setting a second baroreflex stimulation level when the activity level is determined to be the first activity level, wherein the first baroreflex stimulation level is higher than the second baroreflex stimulation level.  
   
   
       38 . The method of  claim 35 , wherein: 
 the activity level is one of a plurality of activity levels and the baroreflex stimulation level is one of a plurality of baroreflex stimulation levels; and    the baroreflex stimulation levels have an inverse relationship with the activity levels such that an incremental increase in the activity level corresponds with an incremental decrease in the baroreflex stimulation level.    
   
   
       39 . The method of  claim 35 , further comprising comparing the activity parameter to a target activity parameter, wherein setting a baroreflex stimulation level includes increasing the baroreflex stimulation level when the acquired activity parameter is lower than the target parameter and decreasing the baroreflex stimulation level when the acquired activity parameter is higher than the target parameter.  
   
   
       40 . The method of  claim 35 , wherein: 
 receiving a signal regarding an activity level includes sensing a heart rate using a sensor of the implantable medical device; and    setting a baroreflex stimulation level includes setting the baroreflex stimulation level based on the heart rate.    
   
   
       41 . The method of  claim 35 , wherein: 
 receiving a signal regarding an activity level includes communicating with an implantable cardiac stimulator to receive heart rate data acquired by the implantable cardiac stimulator; and    setting a baroreflex stimulation level includes setting the baroreflex stimulation level based on the heart rate data.    
   
   
       42 . The method of  claim 35 , wherein: 
 receiving a signal regarding an activity level includes sensing respiration using a sensor of the implantable medical device; and    setting a baroreflex stimulation level includes setting the baroreflex stimulation level based on the respiration.    
   
   
       43 . The method of  claim 42 , wherein sensing respiration includes sensing tidal volume, and setting the baroreflex stimulation level based on the respiration includes setting the baroreflex stimulation level based on the tidal volume.  
   
   
       44 . The method of  claim 42 , wherein sensing respiration includes sensing minute ventilation, and setting the baroreflex stimulation level based on the respiration includes setting the baroreflex stimulation level based on the minute ventilation.  
   
   
       45 . The method of  claim 35 , wherein: 
 receiving a signal regarding an activity level includes communicating with an implantable cardiac stimulator to receive respiration data acquired by the implantable cardiac stimulator; and    setting a baroreflex stimulation level includes setting the baroreflex stimulation level based on the respiration data.    
   
   
       46 . The method of  claim 35 , wherein: 
 receiving a signal regarding an activity level includes sensing acceleration using a sensor of the implantable medical device; and    setting a baroreflex stimulation level includes setting the baroreflex stimulation level based on the acceleration.    
   
   
       47 . The method of  claim 35 , wherein: 
 receiving a signal regarding an activity level includes communicating with an implantable cardiac stimulator to receive acceleration data acquired by the implantable cardiac stimulator; and    setting a baroreflex stimulation level includes setting the baroreflex stimulation level based on the acceleration data.    
   
   
       48 . The method of  claim 35 , further comprising delivering baroreflex stimulation through a lead adapted to be fed through a right ventricle and pulmonary valve into a pulmonary artery.  
   
   
       49 . A method, comprising: 
 determining an activity level;    setting a baroreflex stimulation level based on the activity level; and    applying baroreflex stimulation at the baroreflex stimulation level.    
   
   
       50 . The method of  claim 49 , wherein: 
 determining an activity level includes determining whether the activity level is rest or exercise; and    setting a baroreflex stimulation level based on the activity level includes providing a signal to apply baroreflex stimulation during rest and withdraw baroreflex stimulation during exercise.    
   
   
       51 . The method of  claim 49 , wherein: 
 determining an activity level includes determining whether the activity level is a first activity level or a second activity level, wherein the first activity level is higher than the second activity level; and    setting a baroreflex stimulation level based on the activity level includes setting a first baroreflex stimulation level when the activity level is determined to be the second activity level, and setting a second baroreflex stimulation level when the activity level is determined to be the first activity level, wherein the first baroreflex stimulation level is higher than the second baroreflex stimulation level.    
   
   
       52 . The method of  claim 49 , wherein: 
 the activity level is one of a plurality of activity levels and the baroreflex stimulation level is one of a plurality of baroreflex stimulation levels; and    the baroreflex stimulation levels have an inverse relationship with the activity levels such that an incremental increase in the activity level corresponds with an incremental decrease in the baroreflex stimulation level.    
   
   
       53 . The method of  claim 49 , further comprising comparing the activity parameter to a cardiac activity parameter, wherein setting a baroreflex stimulation level based on the activity level includes increasing the baroreflex stimulation level when the acquired activity parameter is lower than the target parameter and decreasing the baroreflex stimulation level when the acquired activity parameter is higher than the target parameter.  
   
   
       54 . The method of  claim 49 , wherein applying baroreflex stimulation includes stimulating an afferent nerve using a cuff electrode.  
   
   
       55 . The method of  claim 49 , wherein applying baroreflex stimulation includes transvascularly stimulating an afferent nerve using an intravascularly-fed electrode.  
   
   
       56 . The method of  claim 49 , wherein applying baroreflex stimulation includes stimulating a cardiac fat pad using an electrode in the cardiac fat pad.  
   
   
       57 . The method of  claim 49 , wherein applying baroreflex stimulation includes transvascularly stimulating a cardiac fat pad using an intravascularly-fed electrode.