| Objective:Ablation targeting complex fractionated atrial potential (CFAP) has been demonstrated to be effective for atrial fibrillation. Some promising observation have shown that the distribution of CAFP has a relationship with the efferent vagal innervation to atria. This study aimed to investigate the impact of CAFP ablation on vagal modulation to atria and vulnerability to atrial fibrillation.Methods:Ten adult mongrel dogs were involved in this study. Bilateral cervical sympathovagal trunks were decentralized. Metoprolol was given to block sympathetic effects. Multipolar catheters were placed into the right and left atrium and coronary sinus. CAFP was recorded by multipolar catheters during atrial fibrillation induced by S1S2 stimulation during sympathovagal trunks stimulation. Ablation was performed in right atrium and left atrium via trans-septal procedure guided by multipolar catheters. Atrial effective refractory period (ERP), vulnerability window (VW) of atrial fibrillation (AF), and Sinus heart rate were measured at right atrial appendage (RAA), left atrial appendage (LAA), distal coronary sinus(CSd) and proximal coronary sinus(CSp) at baseline (without vagal stimulation) and during vagal stimulation before and after ablation. The underlying tissue were excised from ablative sites and the same sites without ablation as control specimens. Serial sections were taken and stained with hematoxylin and eosin for microscopic examination.Results:(1)Sinus heart rate shortening during vagal stimulation significantly decreased after abaltion(18±8 vs 107±19 beats per minute,P<0.001).It indicated that CAFP ablation attenuate the vagal modulation to the sinus node.(2)ERP shortening during vagal stimulation significantly increased after ablation(17±24 vs 65±22ms at RAA, P<0.001;6±14 vs 41±19ms at LAA,P<0.001;9±10 vs 63±23ms at CSd,P<0.001;4±16 vs 61±21ms at CSp, P<0.001).It indicated that CAFP ablation attenuate the vagal modulation to right atrium,left atrium, and coronary sinus.(3)AF was difficult induced at baseline before and after ablation in all sites(VW close to 0),While VW of atrial fibrillation to vagal stimulation significantly decreased after ablation(18±29 vs 58±13ms at RAA,P<0.001; 19±22 vs 31±24ms at LAA,P<0.001;11±20 vs 52±28ms at CSd,P<0.001; 7±15 vs 62±35ms at CSp,P<0.001).It indicated that CAFP ablation suppress atrial fibrillation mediated by enhanced vagal activity.(4)The architecture of individual ganglia was significantly altered after ablation.Conclusions:The decreased Sinus heart rate and ERP shortening to vagal stimulation after CFAP ablation indicates that CFAP ablation ate- nuate the vagal modulation to atria,thereby suppressing atrial fibrillation mediated by enhanced vagal activity. |
