title: Effect of atrial dilatation on electrophysiologic properties and inducibility of atrial fibrillation.
abstract: BACKGROUND
  Atrial dilatation may play an important role in the occurrence of atrial fibrillation (AF) in clinical situations. However, the electrophysiologic characteristics of dilated atria are still unclear.
  
  
  RESULTS
  In 18 isolated Langendorff-perfused canine hearts (14.6 +/- 2.2 kg), we measured atrial effective refractory periods (ERPs) at four different sites, conduction velocity and percentage of slow conduction on the right atrium (using a high-density electrode plaque), and assessed the inducibility of AF at the baseline (0 cm H(2)O) and high (15 cm H(2)O) atrial pressure. The atrial ERPs did not change significantly, but the dispersion of ERP increased significantly (40 +/- 18 vs 25 +/- 9 vs ms, p = 0.01) during high atrial pressure. The percentage of slow conduction (< 25 cm/s) over the mapping area, and the inducibility of AF increased during high atrial pressure (23.7 +/- 10.2 % vs 32.1 +/- 12.5 %, p = 0.02). The AF inducibility significantly correlated with the ERP dispersion (R = 0.75, p < 0.001) and maximal percentage of slow conduction (R = 0.88, p < 0.001). Furthermore, ERPs were significantly shorter in the induced AF group than those without induced AF (68 +/- 17 vs 84 +/- 16 ms, P < 0.05).
  
  
  CONCLUSIONS
  The increased inhomogenity in atrial electrophysiological properties during atrial dilatation contributed to the inducibility of AF.
authors.affiliation: Division of Cardiology, Department of Medicine, Institute of Clinical Medicine and Cardiovascular Research Institute, National Yang-Ming University and Veterans General Hospital-Taichung, Taiwan.
authors.forename: Jin-Long
authors.initials: JL
authors.lastname: Huang
authors.forename: Ching-Tai
authors.initials: CT
authors.lastname: Tai
authors.forename: Jung-Ta
authors.initials: JT
authors.lastname: Chen
authors.forename: Chih-Tai
authors.initials: CT
authors.lastname: Ting
authors.forename: Ying-Tsung
authors.initials: YT
authors.lastname: Chen
authors.forename: Mau-Song
authors.initials: MS
authors.lastname: Chang
authors.forename: Shih-Ann
authors.initials: SA
authors.lastname: Chen
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology*; D016275:Atrial Function / Q000502:physiology*; D004106:Dilatation / Q000009:adverse effects*; D004198:Disease Susceptibility; D004285:Dogs; D022062:Electrophysiologic Techniques, Cardiac / Q000009:adverse effects*; D066298:In Vitro Techniques