Proactive Esophageal Cooling Protects Against Thermal Insults During High-Power Short-Duration Radiofrequency Ablation

Abstract

Background: Atrioesophageal fistula (AEF) is a severe complication of left atrial radiofrequency (RF) ablation for the treatment of atrial fibrillation. Proactive cooling with a novel cooling device has been shown to significantly reduce thermal injury, with no AEFs yet encountered after thousands of treatments worldwide. Computer modeling suggested that lethal temperatures could be avoided with moderate-power and moderate-duration RF ablation. We aimed to evaluate the effects of proactive cooling during high-power short-duration (HPSD) ablation, and compare the computed results to clinical data and recently published experimental data. Methods: A computer model accounting for the left atrium and esophagus including the active cooling device was created. We used both the Arrhenius equation and 50oC isotherm to estimate the esophageal thermal damage during 50 W, 10 second and 90 W, 4 second RF ablations. Results: Under control conditions, temperatures across the esophageal wall exceeded the lethal isotherm, in agreement with recent experimental data. With proactive esophageal cooling in place, temperatures in the esophageal tissue were significantly reduced, with the resulting fraction of esophageal damage reduced by 74% under 50 W and 10 seconds of ablation, and by 82% under 90 W and 4 seconds of ablation. Esophageal damage was restricted to the epi-esophageal region, sparing the remainder of the esophageal tissue, including the mucosal surface. Conclusions: Proactive esophageal cooling significantly reduced temperatures and the resulting fraction of damage in the esophagus during HPSD ablation. These findings offer a mechanistic rationale explaining the absence of AEF encountered to date using proactive esophageal cooling.