Effect of epicardial fat on ablation performance: a three-energy source comparison

To investigate the effect of epicardial fat on surgical atrial fibrillation ablation performance using an in vitro model. Two tissue models were employed to investigate standard penetration and maximal lesion depth performance of bipolar radiofrequency (RF), microwave, and laser energy sources.

Ventricular veal tissue was utilized in various thicknesses (3 mm, 5 mm, 7 mm, 15 mm). Epicardial fat was modeled by layering porcine fat (1 mm, 2 mm and 4 mm) on moistened tissue. In each group, 8 to 10 lesions were created. Post ablation, tissue samples were sectioned and ablation depth of each myocardial section measured using 1% tetrazolium tetrachloride dye solution.

The laser energy source produced nearly 100% transmural lesions in almost all study groups irrespective of myocardium thickness and fat thickness. The microwave device maintained transmurality in all 3-mm and most 5-mm myocardium trials but fell to near zero with all 7-mm myocardium trials. The bipolar RF maintained transmurality only when no fat was applied. In the maximal lesion depth models, the laser was capable of producing lesions >8 mm with no fat and >6 mm with either 2 mm or 4 mm of fat present. The microwave produced lesions in the no fat (>6 mm) and 2-mm (>4 mm) fat group. The bipolar RF produced 83% transmurality with no fat and zero percent transmurality with 2 mm of fat present.

Epicardial fat can severely limit transmurality in energy sources that utilize conductive heating. Laser energy was uniformly superior at producing both transmural and deep lesions irrespective of the presence of fat.