Effect of atrial dilatation on electrophysiologic properties and inducibility of atrial fibrillation.
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.
Huang
Jin-Long
JL
Division of Cardiology, Department of Medicine, Institute of Clinical Medicine and Cardiovascular Research Institute, National Yang-Ming University and Veterans General Hospital-Taichung, Taiwan.
Tai
Ching-Tai
CT
Chen
Jung-Ta
JT
Ting
Chih-Tai
CT
Chen
Ying-Tsung
YT
Chang
Mau-Song
MS
Chen
Shih-Ann
SA
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