Combined parasympathetic stimulation and cardiac pacing

Abstract

Apparatus for treating a subject suffering from spontaneous atrial fibrillation includes an electrode device, adapted to be coupled to a vagus nerve of the subject, and a control unit, adapted to drive the electrode device to apply an electrical current to the vagus nerve, and to configure the current to maintain the spontaneous AF for at least about 24 hours, so as to modify blood flow within the atria and reduce risk of thromboembolic events.

1 - 303 . (canceled)  
     
     
         304 . Treatment apparatus, comprising: 
 an electrode device, configured to be coupled to tissue of a subject suffering from atrial fibrillation (AF), the tissue selected from the group consisting of: a vagus nerve, an epicardial fat pad, and atrial tissue;    a pacing device, configured to be applied to a heart of the subject; and    a control unit, configured to:    drive the electrode device to apply an electrical current to the tissue,    drive the pacing device to apply a pacing signal to the heart, and    configure the current and the pacing signal so as to treat the AF.    
     
     
         305 . Apparatus according to  claim 304 , wherein the control unit is adapted to configure the pacing signal to have a pulse repletion interval having a duration of between about 50% and about 200% of an atrial refractory period of the subject.  
     
     
         306 . Apparatus according to  claim 304 , wherein the control unit is adapted to configure the pacing signal to have a pulse repetition interval having a duration of between about 15 ms and about 190 ms.  
     
     
         307 . Apparatus according to  claim 304 , wherein the control unit is adapted to configure the current to modulate an atrial refractory period of the subject.  
     
     
         308 . (canceled)  
     
     
         309 . A treatment method, comprising: 
 identifying that a subject suffers from atrial fibrillation;    applying an electrical current to tissue of the subject selected from the group consisting of: a vagus nerve, an epicardial fat pad, and atrial tissue;    applying a pacing signal to a heart of the subject; and    configuring the current and the pacing signal so as to treat the AF.    
     
     
         310 . A method according to  claim 309 , wherein configuring the pacing signal comprises configuring the pacing signal to have a pulse repetition interval having a duration of between about 50% and about 200% of an atrial refractory period of the subject.  
     
     
         311 . A method according to  claim 309 , wherein configuring the pacing signal comprises configuring the pacing signal to have a pulse repetition interval having a duration of between about 15 ms and about 190 ms.  
     
     
         312 . A method according to  claim 309 , wherein configuring the current comprises configuring the current to modulate an atrial refractory period of the subject.  
     
     
         313 - 360 . (canceled)  
     
     
         361 . Apparatus according to  claim 304 , and comprising a sensor, configured to detect an occurrence of the AF and generate a sensor signal indicative thereof, wherein the control unit is configured to: 
 during a first period, drive the pacing device to apply the pacing signal to the heart, and drive the electrode device to apply the electrical current to the tissue, and    responsive to the sensor signal, during a second period following the first period, withhold the electrode device from applying the electrical current to the tissue.    
     
     
         362 . Apparatus according to  claim 361 , wherein the control unit is configured to configure a parameter of at least one of the first and second periods to be such as to restore normal sinus rhythm (NSR) of the subject within 2 hours after initiation of the second period.  
     
     
         363 . Apparatus according to  claim 361 , wherein the control unit is configured to, during the first period, drive the pacing device and drive the electrode device to apply the current responsive to the sensor signal.  
     
     
         364 . Apparatus according to  claim 361 , wherein the control unit is configured to withhold the pacing device from pacing the heart during at least a portion of the second period.  
     
     
         365 . Apparatus according to  claim 361 , wherein the control unit is configured to withhold the electrode device from applying the electrical current during the second period responsive to an indication in the sensor signal of a P-wave of the subject.  
     
     
         366 . Apparatus according to  claim 361 , wherein the sensor is configured to generate the sensor signal responsive to a measure of pressure, selected from the group consisting of: atrial pressure, venous pressure, and arterial pressure.  
     
     
         367 . A method according to  claim 309 , wherein applying the current and applying the pacing signal comprise: 
 during a first period, applying the pacing signal to the heart, and applying the current to the tissue;    detecting an occurrence of the AF; and    responsive to detecting the AF, during a second period following the first period, withholding applying the current to the tissue.    
     
     
         368 . A method according to  claim 367 , wherein applying the current and applying the pacing signal comprise configuring a parameter of at least one of the first and second periods to be such as to restore normal sinus rhythm (NSR) of the subject within 2 hours after initiation of the second period.  
     
     
         369 . A method according to  claim 367 , wherein the tissue includes the vagus nerve, and wherein applying the current comprises: 
 applying a stimulating current and an inhibiting current;    configuring the stimulating current to induce action potentials in the vagus nerve; and    configuring the inhibiting current to inhibit action potentials induced by the stimulating current and traveling in the vagus nerve in an afferent direction toward a brain of the subject.    
     
     
         370 . A method according to  claim 367 , wherein pacing the heart and applying the current during the first period comprise pacing the heart and applying the current during the first period responsive to the detecting of the AF.  
     
     
         371 . A method according to  claim 367 , comprising withholding pacing the heart during at least a portion of the second period.  
     
     
         372 . A method according to  claim 367 , wherein applying the current during the first period comprises applying the electrical current substantially without changing a parameter of the current during the first period, and with an amplitude greater than about 6 milliamps.  
     
     
         373 . A method according to  claim 367 , comprising detecting a P-wave of the subject, wherein withholding applying the current during the second period comprises withholding applying the current during the second period responsive to the detecting of the P-wave.  
     
     
         374 . A method according to  claim 367 , wherein detecting the occurrence of the AF comprises sensing a measure of at least one ventricular response parameter, selected from the list consisting of: a ventricular response rate and a ventricular response variability.  
     
     
         375 . A method according to  claim 367 , wherein detecting the occurrence of the AF comprises sensing a measure of pressure, selected from the list consisting of: atrial pressure, venous pressure, and arterial pressure.  
     
     
         376 . A method according to  claim 367 , wherein detecting the occurrence of the AF comprises: 
 sensing a measure of pressure, selected from the list consisting of: atrial pressure, venous pressure, and arterial pressure;    sensing an indication of ventricular contraction; and    analyzing at least one relationship between the measure of the pressure and the indication of the ventricular contraction.