The Changes Of Vagal Modulation To Atria In Atrial Remodeling In Dogs

Purpose:Perturbation of normal atrial electrophysiological properties by rapid atrial rates that promotes atrial fibrillation (AF) has been termed electrophysiological remodeling. Shortening of refractoriness has been described as a hallmark of electrophysiological remodeling. It has been proposed that other electrophysiological properties such as the spatial dispersion of atrial refractoriness and conduction velocity are also important elements of electrophysiological remodeling. Atrial remodeling takes an important role in perpetuation of atrial fibrillation. Vagus has a close relationship with atrial fibrillation. However, little is known about the relationship between the vagal modulation to atria and atrial remodeling. This study aimed to investigate the changes of vagal modulation to atria in atrial remodeling in dogs.Methods: Nine adult mongrel dogs under general anesthesia were involved in this study. Bilateral cervical sympathovagal trunks were decentrated. Multipolar 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 through RV catheter. Metoprolol was given to block sympathetic effects. Atrial remodeling was performed by 600bpm pacing through RA catheter for 30 minutes. Atrial effective refractory period (ERP) and vulnerability window (VW)of atrial fibrillation were measured with and without vagal stimulation before and after atrial remodeling.Results:ERP decreased at baseline after atrial remodling(97.78±16.41 vs 85.56±15.90 ms,P=0.005 at CS; 100±20.62 vs 82.22±19.86 ms,P =0.021 at RA). ERP during vagal stimulation decreased after atrial...