Abstract 2587: Acute Effects of Surgical Ablation Procedures on Atrial Autonomic Innervation
Background The effect of surgical ablation lines on the innervation of the myocardium and its response to autonomic stimuli has not been previously described. This study examined the effect of bipolar radiofrequency ablation (RFA) on atrial autonomic innervation by comparing pulmonary vein isolation (PVI) and the biatrial Cox-Maze lesion set (CM.)
Methods Right and left vagosympathetic trunks (RVST, LVST) and right and left stellate ganglia were isolated in 12 canines. Atropine (N=6) and nadolol (N=6) were given to block parasympathetic and sympathetic responses, respectively. Electrode plaques were placed on the atria to record 250 unipolar electrograms. Each nerve was stimulated before RFA lesions, after PVI, and after CM. Heart rate (HR) and atrio-ventricular (AV) interval changes were recorded. Changes in QRST area relative to an isoelectric diastolic baseline (an index of local innervation) were calculated at each electrode site during stimulation. Areas were averaged.
Results Sympathetic stimulation of each nerve and parasympathetic stimulation of RVST and LVST caused significant changes in HR and AV interval. (Table⇓) After PVI, HR changes due to LVST sympathetic and parasympathetic stimulation were eliminated. The CM eliminated right stellate sympathetic effects on HR. Heart rate changes remained after CM with RVST and left stellate sympathetic and RVST parasympathetic stimulation. There was no significant effect of the lesions on AV interval changes. Stimulation of 50% of nerves after PVI produced area changes significantly different from control. After CM, 63% of nerves produced changes different from PVI.
Conclusions Surgical ablation procedures disrupted sympathetic and parasympathetic innervation affecting HR, but not AV interval. Autonomic innervation affecting the atria was disrupted by PVI and additionally by the full CM. However, residual effects throughout the atria and on HR were seen even after the complete CM lesion set.