title: Impact of right upper pulmonary vein isolation on atrial vagal innervation and vulnerability to atrial fibrillation.
abstract: BACKGROUND
  Based on the hypothesis that pulmonary vein isolation could result in the damage of the epicardial fat pads, this study aimed to investigated the impact of right upper pulmonary vein (RUPV) isolation on vagal innervation to atria.
  
  
  METHODS
  Bilateral cervical sympathovagal trunks were decentralized in 6 dogs. Metoprolol was given to block sympathetic effects. Multipolar catheters were placed into the right atrium (RA) and coronary sinus (CS). RUPV isolation was performed via transseptal procedure. Atrial effective refractory period (ERP), vulnerability window (VW) of atrial fibrillation (AF), and sinus rhythm cycle length (SCL) were measured at RA and distal coronary sinus (CSd) at baseline and vagal stimulation before and after RUPV isolation. Serial sections of underlying tissues before and after ablation were stained with haematoxylin and eosin.
  
  
  RESULTS
  SCL decreased significantly during vagal stimulation before RUPV isolation (197 +/- 21 vs 13 +/- 32 beats per minute, P < 0.001), but remained unchanged after RUPV isolation (162 +/- 29 vs 140 +/- 39 beats per minute, P > 0.05). ERP increased significantly before RUPV isolation compared with that during vagal stimulation [(85.00 +/- 24.29) ms vs (21.67 +/- 9.83) ms at RA, P < 0.001; (90.00 +/- 15.49) ms vs (33.33 +/- 25.03) ms at CSd P < 0.005], but ERP at baseline hardly changed after RUPV isolation compared with that during vagal stimulation [(103.33 +/- 22.50) vs (95.00 +/- 16.43) ms at RA, P = 0.09; (98.33 +/- 24.83) vs (75.00 +/- 29.50) ms at CSd, P = 0.009]. The ERP shortening during vagal stimulation after RUPV isolation decreased significantly [(63.33 +/- 22.51) ms vs (8.33 +/- 9.83) ms at RA, P < 0.005; (56.67 +/- 20.66) ms vs (23.33 +/- 13.66) ms at CSd, P < 0.05]. AF was rarely induced at baseline before and after RUPV isolation (VW close to 0), while VW of AF to vagal stimulation significantly decreased after RUPV isolation [(40.00 +/- 10.95) vs 0 ms at RA, P < 0.001; (45.00 +/- 32.09) vs (15.00 +/- 23.45) ms at CS, P < 0.05]. The architecture of individual ganglia was significantly altered after ablation.
  
  
  CONCLUSIONS
  The less ERP shortening to vagal stimulation and altered architecture of individual ganglia after right upper pulmonary vein isolation indicate that isolation may result in damage of the epicardial fat pads, thereby attenuating the vagal innervation to atria. The decreased vulnerability window of atrial fibrillation indicates that vagal denervation may contribute to its suppression.
authors.affiliation: Department of Cardiology, First Affiliated Hospital of Dalian Medical University, Dalian 116011, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Liu
authors.forename: Shu-long
authors.initials: SL
authors.lastname: Zhang
authors.forename: Ying-xue
authors.initials: YX
authors.lastname: Dong
authors.forename: Hong-wei
authors.initials: HW
authors.lastname: Zhao
authors.forename: Lian-jun
authors.initials: LJ
authors.lastname: Gao
authors.forename: Xiao-meng
authors.initials: XM
authors.lastname: Yin
authors.forename: Shi-jun
authors.initials: SJ
authors.lastname: Li
authors.forename: Zhi-hu
authors.initials: ZH
authors.lastname: Lin
authors.forename: Yan-zong
authors.initials: YZ
authors.lastname: Yang
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D004285:Dogs; D005260:Female; D005724:Ganglia / Q000473:pathology; D006325:Heart Atria / Q000294:innervation*; D008297:Male; D011667:Pulmonary Veins / Q000601:surgery*; D012032:Refractory Period, Electrophysiological; D014630:Vagus Nerve / Q000502:physiology*