Atrial fibrillation propagates through gaps in ablation lines: Implications for ablative treatment of atrial fibrillation

Background It has been hypothesized that atrial lesions must be transmural to successfully cure atrial fibrillation (AF). However, ablation lines often do not extend completely across the atrial wall. Objective The purpose of this study was to determine the effect of residual gaps on conduction properties of atrial tissue. Methods Canine right atria (n = 13) were isolated, perfused, and mounted on a 250-lead electrode plaque. The atria were divided with a bipolar radiofrequency ablation clamp, leaving a gap that was progressively narrowed. Conduction velocities at varying pacing rates and AF frequencies were measured before and after ablations. AF was induced with an extra stimulus and acetylcholine. Results Gap widths from 11.2 to 1.1 mm were examined. Conduction velocities through gaps were dependent cycle length ( P = .002) and gap size ( P