Abstract 4107: Gaps in the Ablation Line as Potential Cause of Recovery of Conduction Block
Atrial fibrillation can be cured by placing lines of conduction block around the pulmonary veins using ablation. A significant percentage of patients, however, have recurrences requiring repeat ablation procedures. It has been shown that ablation lines can have gaps, and that the conductivity of myocardium in gaps can be reduced by tissue heating. In this study, we looked at the role of these gaps and the effect of change in the conductivity through these gaps on the propagation of electrical wavefronts across ablation lines. We implemented a bidomain model of the cardiac syncytium using the Luo-Rudy I action potential model. A two-dimensional sheet measuring 8 mm by 8 mm was simulated with an ablation line having a gap. Gaps of varying lengths, conductivity and orientation were created. For ablation lines that are parallel to the fiber direction, the relationship between gap length and conductivity is shown in the attached figure⇓. The minimum gap length that supports propagation with normal conductivity in the gap is 1.5 mm; as the conductivity decreases the minimum gap length that supports conduction increases substantially. For ablation lines perpendicular to the fiber direction the minimum gap length that supports propagation was 0.3 mm and with decreasing conductivity the minimum gap length that supports conduction increased. We conclude that conduction block can occur across ablation lines with gaps. Moreover with potential recovery of conductivity over time, ablation lines even with large gaps that showed conduction block acutely can support propagation over time, allowing recurrences of arrhythmias.