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Objective Mechanisms of pulmonary vein isolation (PVI) for atrial fibrillation remain controversy. This study aimed to investigate the impact of PVI on vagal modulation to atria. Methods Eighteen adult mongrel dogs under general anesthesia were randomly divided into two groups. Bilateral cervical sympathovagal trunks were decentralized and sympathetic effects was blocked by metoprolol administration. Atrial electrical remodeling (AER) was established by rapid right atrial pacing at the rate of 600 bpm for 30 minutes. PVI was performed in group A. Atrial effective refractory period (ERP), vulnerability window (VW) of atrial fibrillation, and sinus rhythm cycle length (SCL) were measured at baseline and during vagal stimulation before and after atrial rapid pacing with and without PVI at right atrial appendage (RAA), left atrial appendage (LAA), distal coronary sinus (CSd) and proximal coronary sinus (CSp). Results (1) Effects of PVI on vagal modulation: Shortening of SCL during vagal stimulation decreased significantly after PVI compared with that before PVI in group A (P<0.001). Shortening of ERP during vagal stimulation decreaseed significantly after PVI compared with that before PVI (P<0.05). VW of atrial fibrillation during vagal stimulation decreased significantly after PVI compared with that before PVI (P<0.05). (2) Effects of PVI on AER: shortening of ERP before and after atrial rapid pacing increased significantly at baseline and vagal stimulation in group B compared with that in group A (P<0.05). VW during vagal stimulation increased significantly after atrial rapid pacing in group B (P<0.05). Conclusion PVI attenuates the vagal modulation to the atria, thereby decreases the susceptibility to atrial fibrillation mediated by vagal activity. PVI releases AER, which maybe contributes to the vagal denervation. Ourstudy indicates that PVI not only can eradicate triggered foci but also modify substrates for AF.
Objective Mechanisms of pulmonary vein isolation (PVI) for atrial fibrillation remain controversy. This study aimed to investigate the impact of PVI on vagal modulation to atria. Bilateral cervical sympathovagal trunks were decentralized and sympathetic effects was blocked by metoprolol administration. Atrial electrical remodeling (AER) was established by rapid right atrial pacing at the rate of 600 bpm for 30 minutes. PVI was performed in group A. Atrial effective refractory period (ERP), vulnerability window (VW) of atrial fibrillation, and sinus rhythm cycle length (SCL) were measured at baseline and during vagal stimulation before and after atrial rapid pacing with and without PVI at right atrial appendage (RAA), left atrial appendage (LAA) Results (1) Effects of PVI on vagal modulation: Shortening of SCL during vagal st Significantly after PVI compared with that before PVI in group A (P <0.001). Shortening of ERP during vagal stimulation decreased significantly after PVI compared with that before PVI (P <0.05). VW of atrial fibrillation during vagal stimulation significantly significantly after PVI compared with that before PVI (P <0.05). (2) Effects of PVI on AER: shortening of ERP before and after atrial rapid pacing increased significantly at baseline and vagal stimulation in group B compared with that in group A (P <0.05 ). VW during vaginal stimulation increased significantly after atrial rapid pacing in group B (P <0.05). Conclusion PVI attenuates the vagal modulation to the atria, so reduces the susceptibility to atrial fibrillation mediated by vagal activity. PVI releases AER, which maybe contributes to the vagal denervation. Ourstudy said that PVI not only can eradicate triggered foci but also modify substrates for AF.