Persistence of Atrial Fibrillation After Its Induction— Importance of the Duration and Dispersion of Atrial Refractoriness and Electrical Remodeling:

Background: The electrophysiologic mechanisms of the persistence of atrial fibrillation (AF) after its initiation are not well understood. Therefore, the electrophysiologic charac teristics of the right atrium were evaluated in an acute, pacing-induced model of AF in the pig in order to identify parameters associated with persistence of AF.Methods and Results: AF was induced by rapid atrial pacing in 30 anesthetized, open- chest, juvenile pigs. Sustained (S) AF was defined as that lasting > 10 minutes, nonsustained (NS) AF 30 seconds, and no (N) AF <30 seconds. Activation mapping and programmed stimulation (S1S1 = 200 ms) was performed at 56 electrodes on the right atrial free wall, to determine ERP (mean and minimum), dispersion of refractoriness (ERPdisp, ELEdisp), conduction velocity (CV), wavelength, AF cycle length (mean of 10 beats), and AF cycle length/time (electrical remodeling). SAF was induced in 10 pigs, NSAF in 9, and NAF in 11. AF cycle length was shorter in SAF and/vs NS vs...