Extracardiac Vagal Stimulation (ECVS)
The amount of vagal denervation was progressively evaluated by stepwise ECVS in the group ECVS. It was obtained without dissection or direct contact with the vagus nerve according to the original technique10. A quadripolar EP catheter was advanced by the superior vena cava and internal jugular vein, up to the right or left jugular foramen, Figure 1-B,D. Generally, this place is the closest one to the vagus nerve, Figure 1-C. ECVS was attained by pulsed electric field between the pole 1 and 3 of the quadripolar catheter with amplitude of 1V/kg body weight up to 70V with 50 microseconds width and a frequency of 50Hz for 5 seconds, within the jugular vein, Figure 1-A.
Figure 1
A typical response is transitory asystole and/or AV block, Figure 2-A and B. A new ECVS was repeated under atrial pacing 10 to 20ppm higher than the sinus rate, Figure 2-B. Typical response in all cases is transitory total AV block. The ECVS was performed before ablation to record the basal response, during the procedure for guiding the denervation progression, and at the end to confirm the endpoint, Figure 2-C.
Figure 2