Abstract 3495: Vagal Denervation For Atrial Fibrillation: Temporal Modification And Early Phase Recovery Of Parasympathetic Function After Surgical Ablation Of Ganglionated Plexi
Background : Ablation of ganglionated plexi (GP) may have benefits in treating and preventing atrial fibrillation. There are numerous GP around the large vessels in the atria. Little is known about the extent of vagal denervation and recovery of parasympathetic function after ablation.This study examined electrophysiological changes in parasympathetic response to the atria after surgical ablation.
Methods : Eighteen dogs were divided into 3 groups: Group 1 (N=6) had focal ablation of 4 epicardial fat pads; Group 2 (N=6) had pulmonary vein isolation (PVI) combined with GP ablation; and Group 3 (N=6) had posterior left atrial isolation combined with GP ablation. High frequency stimulation was applied to 4 epicardial GP fat pads to examine vagal reflexes in all groups pre-ablation. All 4 GP fat pads were ablated regardless of vagal reflexes. Sinus and atrioventricular (AV) interval changes during bilateral vagosympathetic trunk stimulation were examined before, after, and at four weeks post-ablation. Vagally induced effective refractory period (ERP) changes and mean QRST area changes relative to an isoelectric baseline (index of local innervation) were examined in 5 atrial regions using epicardial templates with 250 unipolar electrodes. Each dog was Holter-monitored preoperatively and weekly postoperatively to examine heart rate variability.
Results : Sinus and AV interval changes decreased immediately post-ablation, but sinus interval changes were restored significantly after 4 weeks in all groups. Ablation modified vagal effects on ERP or QRST area changes heterogeneously in Groups 1 and 2. In Group 3, regional vagal effects were attenuated extensively post-ablation in both atria except the right atrial appendage. Chronically, vagal stimulation increased QRST area change over pre-ablation values in 5 regions in all groups. Heart rate variability decreased post-ablation and remained significantly low at 4 weeks in all groups.
Conclusions :Surgical ablation of GP incrementally acutely denervated the atria. Restoration of vagal effects after 4 weeks suggests early reinnervation of the atria.