Short-term autonomic denervation of the atria using botulinum toxin.
OBJECTIVE
Major epicardial fat pads contain cardiac ganglionated plexi (GP) of the autonomic nervous system. Autonomic denervation may improve the success rate of atrial fibrillation (AF) ablation. This study was designed to elucidate the acute effects of blocking the right atrium-pulmonary vein (RA-PV) and left atrium-inferior vena cava (LA-IVC) fat pads on the electrophysiologic characteristics of the atrium and AF inducibility with a botulinum toxin injection.


METHODS
Eight mongrel dogs were studied. The RA-PV and LA-IVC fat pads were exposed through a median thoracotomy. Botulinum toxin (BT, 50 U to each fat pad, n=6) or normal saline (NS, n=2) was injected in the entire area of two fat pads. The study protocol was applied before injection and repeated at 1, 2, 3, 4, and 5 hours thereafter. The sinus rate, ventricular rate during rapid atrial pacing with a cycle length of 50 ms, and AF inducibility were measured with and without vagal stimulation (VS). Bilateral cervical VS was applied (20 Hz, 0.2 ms, 5.6±2.0 V). AF inducibility was evaluated with burst pacing with 200 impulses at a 50-ms cycle length.


RESULTS
VS effects on the sinus node and AF inducibility were eliminated a few hours after injection of BT; these changes were not observed after injection of NS.


CONCLUSIONS
Short-term autonomic denervation of the atria was achieved by blocking the major epicardial GP with BT.
Oh
Seil
S
Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
Choi
Eue-Keun
EK
Choi
Yun-Shik
YS