Abstract 11481: Biatrial Epicardial Neuroablation Limits Atrial Fibrillation Susceptibility in a Canine Chronic Rapid Atrial Pacing Model
Background: Epicardial ganglionated plexuses have recently become targets of both transcatheter and surgical ablative therapy of AF. The goal of this study was to determine the effects of biatrial epicardial, rather than endocardial, neuroablation on atrial refractoriness and AF induction in a chronic canine model of rapid atrial pacing (RAP).
Methods: Fifteen canines underwent bilateral minithoracotomies with thoracoscopic guidance. Electrophysiological data was recorded in all dogs at baseline and following six weeks of RAP (400 bpm). Atrial effective refractory period (ERP) and AF inducibility were measured by decremental S1 pacing in the right (RAFW) and left (LAFW) atrial free walls and appendages. The ablation group (n=8) underwent excision of the right atrial and three left atrial ganglionated plexuses using an ultrasonic scalpel, thus assuring preservation of the underlying myocardium. The identical protocol was followed in the control group (n=7) without ganglionated plexus excision.
Results: After six weeks of RAP, only the control groups showed significant shortening of the atrial ERP compared to baseline (ablation = 112.3±23.6ms vs 101.0±29.4ms, p=0.18; control = 110.1±22.0 vs 77.8±19.9ms, p<0.02). While ERP was similar between the groups at baseline (p=0.79), at six weeks the control group showed greater shortening (32.3±9.5ms vs 11.3±24.6ms, p<0.05). At six weeks, AF inducibility was increased in all paced regions except the RAFW. When analyzed by treatment group, rate of AF induction increased significantly in the control group only (27±22% vs 64.0±10.0, p<0.012), with no change in the ablation group (21±14% vs 25±12%, p=0.16).
Conclusion: In this chronic canine model of RAP, biatrial epicardial ganglionated plexus ablation attenuated electrophysiologic remodelling, limiting an increase in AF susceptibility. These results can be attributed primarily to a neurogenic mechanism since ablation of the underlying myocardium was avoided. These findings provide an experimental basis supporting the use of biatrial ganglionated plexus ablation as an adjunct to myocardial targets in the surgery of AF.
- © 2011 by American Heart Association, Inc.