Valvular leaflets and epicardial fat have a significant effect on lesion size in RF ablation

Abstract Introduction Radiofrequency (RF) current is the classic ablation technology in the EP lab. Underlying RF ablation parameters, such as RF power, impedance, duration and contact force are used to calculate expected lesion size. Furthermore, lesion indices (LSI, AI) are applied to estimate expected lesion durability and contiguity. Purpose The aim of this ex-vivo study was to assess the influence of valvular tissue and epicardial fat on RF lesion creation. Methods An ex-vivo porcine model was created to create RF lesions under standardized conditions. Temperature was constantly kept at 37°C using a thermostat and a circulation pump was used to imitate blood flow. A contact force sensing ablation catheter (ST SF) was used to create RF lesions using predefined RF parameters (30W/50W, CF 10g, 30sec). Lesions using the same RF parameters were created above and right next to mitral valve leaflets as well as on epicardial fat tissue (figure 1). Lesions were then dissected, and lesion depths and diameters were measured using a digital precision caliper. Results A total of 210 lesions were created. RF lesions ablated on valvular leaflets showed significantly smaller lesion depth and lesion diameter when compared to RF lesions ablated right next to valvular (diameter 8.0±2.0mm vs 10.8±1.8mm; depth 4.4±1.2 vs 7.7±1.6mm, p<0.01). Lesions ablated on epicardial fat were significantly smaller in diameter (9.2±1.5) and depth (6.5±1.8) than purely endocardial lesions (p<0.01). Examples are depicted in figure 1. Conclusions Valvular leaflets as well as epicardial fat tissue have a significant influence on RF lesion creation. RF ablation performed on valvular leaflets or epicardial fat results in significantly (p<0.01) smaller lesions when compared to RF ablations directly on endocardial tissue. This should be considered in ablations of accessory pathways and epicardial procedures.Figure 1