Impact Of Vagal Block On Atrial Remodeling In Dogs

Objectives Atrial fibrillation(AF) is the most common persistent tachycardia. Both atrial electrical remodeling and parasympathetic nerve take an important role in perpetuation of atrial fibrillation, More and more evidences suggest that atrial vagal denervation can reduce AF. However, little is known about the impact of vagal block on atrial electrical remodeling. In this study atrial effective refractory period was measured to investigate the impact of vagal block on atrial electrical remodeling based on the ERP shortening after atrial electrical remodeling.Methods eight adult mongrel dogs under general anesthesia were involved in this study. Bilateral cervical sympathovagal strunks were decentralized. Metoprolol and atropine were given to block sympathetic and vagal effects. Mutipolar catheters were placed into right atria(RA), coronary sinus(CS), and right ventricle(RV). Complete atrioventricular node block was achieved by His bundle ablation and temporary RV pacing was applied to avoid the arrhythmia induced by vagal stimulation. Atrial electrical remodeling was performed by 600bpm atrial pacing for 30 minutes. ERP and vulnerability window(VW)of atrial fibrillation were measured with and without vagal stimulation before and after atrial electrical remodeling.Results ① Before atrial electrical remodeling, ERP shortened significantly during vagal stimulation compared with ERP measured at baseline either at RA or at CS before atropine administration (RA: 103.75± 18.47msec at baseline,58.75±44.54msec during vagal stimulation, P=0.009 CS:108.75±24.16msec at baseline, 58.75±36.03msec during vagal stimula-tion,P=0.003). ERP almost remained consistent before and after atropine...