Vagal denervation and atrial fibrillation inducibility: epicardial fat pad ablation does not have long-term effects.
BACKGROUND
Major epicardial fat pads contain cardiac ganglionated plexi of the autonomic, predominantly vagal nerves. Vagal denervation may improve the success rate of atrial fibrillation (AF) treatment.


OBJECTIVE
The purpose of this study was to elucidate the long-term effects of fat pad ablation on the electrophysiologic characteristics of the atrium and AF inducibility.


METHODS
Six mongrel dogs were studied. Cervical vagal stimulation was applied to determine effects on the sinus node, AV node, atrial effective refractory period (AERP), and AF inducibility. AERP and AF inducibility were evaluated at both the right atrial and left atrial appendages and at the right atrial and left atrial free walls. Radiofrequency energy was delivered epicardially to the entire areas of two major fat pads: right pulmonary vein fat pad and inferior vena cava-left atrium fat pad. Cervical vagal stimulation then was applied to confirm the acute effects of fat pad ablation. The same evaluation was repeated 4 weeks later.


RESULTS
The effects of vagal stimulation on the sinus node, AV node, and AERP were significantly eliminated immediately after fat pad ablation. However, these denervation effects disappeared after 4 weeks. At baseline, AF inducibility was increased by vagal stimulation (right atrial appendage: 72% +/- 31% vs 4.8% +/- 12%; right atrial free wall: 75% +/- 31% vs 0.0% +/- 0.0%; left atrial appendage: 60% +/- 29% vs 0.0% +/- 0.0%; left atrial free wall: 65% +/- 42% vs 0.0% +/- 0.0%). Fat pad ablation significantly reduced this vagal stimulation effect (8.3% +/- 20%, 10% +/- 22%, 17% +/- 29%, and 25% +/- 29%, respectively). However, similar to baseline, AF inducibility was strongly augmented by vagal stimulation 4 weeks after fat pad ablation (96% +/- 10%, 100% +/- 0.0%, 100% +/- 0.0%, and 95% +/- 11%, respectively).


CONCLUSIONS
Radiofrequency fat pad ablation may not achieve long-term suppression of AF induction in this canine model.
Oh
Seil
S
Section of Pacing and Electrophysiology, Department of Cardiovascular Medicine, Cleveland Clinic, Ohio 44195, USA.
Zhang
Youhua
Y
Bibevski
Steve
S
Marrouche
Nassir F
NF
Natale
Andrea
A
Mazgalev
Todor N
TN
D000273:Adipose Tissue / Q000294:innervation / Q000473:pathology / Q000601:surgery*; D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000517:prevention & control; D016275:Atrial Function; D001283:Atrioventricular Node / Q000294:innervation; D017115:Catheter Ablation; D004285:Dogs; D004558:Electric Stimulation; D004562:Electrocardiography; D023421:Models, Animal; D010496:Pericardium / Q000294:innervation / Q000473:pathology / Q000601:surgery*; D012849:Sinoatrial Node / Q000294:innervation; D013997:Time Factors; D014628:Vagotomy; D014630:Vagus Nerve / Q000502:physiology / Q000601:surgery*