Modeling esophageal protection from radiofrequency ablation via a cooling device: an analysis of the effects of ablation power and heart wall dimensions

Abstract

Background Esophageal thermal injury can occur after radiofrequency (RF) ablation in the left atrium to treat atrial fibrillation. Existing methods to prevent esophageal injury have various limitations in deployment and uncertainty in efficacy. A new esophageal heat transfer device currently available for whole-body cooling or warming may offer an additional option to prevent esophageal injury. We sought to develop a mathematical model of this process to guide further studies and clinical investigations and compare results to real-world clinical data. Results The model predicts that the esophageal cooling device, even with body-temperature water flow (37 °C) provides a reduction in esophageal thermal injury compared to the case of the non-protected esophagus, with a non-linear direct relationship between lesion depth and the cooling water temperature. Ablation power and cooling water temperature have a significant influence on the peak temperature and the esophageal lesion depth, but even at high RF power up to 50 W, over durations up to 20 s, the cooling device can reduce thermal impact on the esophagus. The model concurs with recent clinical data showing an 83% reduction in transmural thermal injury when using typical operating parameters. Conclusions An esophageal cooling device appears effective for esophageal protection during atrial fibrillation, with model output supporting clinical data. Analysis of the impact of ablation power and heart wall dimensions suggests that cooling water temperature can be adjusted for specific ablation parameters to assure the desired myocardial tissue ablation while keeping the esophagus protected.

Impact of Active Esophageal Cooling on Fluoroscopy Usage During Left Atrial Ablation

“… 7 – 12 The use of high-power, short-duration ablation and the development of an ablation index may offer further safety improvements, but benefits to date in reducing esophageal injury in formal studies using objective endpoints (either magnetic resonance imaging– or endoscopy-proven esophageal injury) remain unclear. 41 , 42 On the other hand, currently available technology that provides active esophageal cooling has suggested benefits in multiple pre-clinical and clinical studies, 11 , 12 , 20 – 22 , 43 , 44 with two pilot RCTs and one confirmatory RCT demonstrating significant reductions in esophageal injury. 20 – 22 Procedural efficiency improvements in the form of reduced fluoroscopy requirements may add another benefit to this approach.…”

Preventing esophageal complications from atrial fibrillation ablation: A review

“…A mathematical modeling analysis of the biophysical effect of the ensoETM device set at different temperatures during AF ablation confirmed the potential to protect the esophagus over a wide range of temperature settings. 75 Projected tissue temperature rise and tissue damage were improved even if the circulating water within the probe was set at normal body temperature.…”

Improved One-year Outcomes After Active Cooling During Left Atrial Radiofrequency Ablation

“…[6] Newer mathematical models have suggested little in uence on atrial tissue temperatures when using a non-expandable active esophageal cooling device. [12,13] Long-term follow-up data from the largest randomized controlled trial of active esophageal cooling suggest a trend towards improved freedom from arrhythmia at one year, with arrhythmia recurrence of 20.3% in actively cooled patients versus 26.8% in patients receiving LET monitoring. [14] Clinical data have shown that lesions placed immediately have a higher likelihood of achieving transmurality-associated unipolar electrograms compared to delayed lesions.…”