Impact of power and contact force on index-guided radiofrequency lesions in an ex vivo porcine heart model

Lesion size index (LSI) and ablation index (AI) are markers of lesion quality that incorporate power, contact force (CF) and time in a weighted formula to estimate lesion size. Although accurate predicting lesion depth in vitro, their precision in lesion size estimation has not been well established for certain power and CF settings. We conducted an experimental ex vivo study to analyse the effect of power and CF in size and morphology of ablation lesions in a porcine heart model.Twenty-four sets of 10 perpendicular epicardial radiofrequency applications were performed with two commercially available catheters (TactiCath, Sensor Enabled; and SmartTouch) on porcine left ventricle submerged in 37 °C saline, combining different power (25, 30, 35, 40, 50 and 60 W) and CF (10 and 20 g) settings, and aiming at a lower (LSI/AI of 5/400) or higher (LSI/AI of 6/550) index. After each application, lesions were cross-sectioned and measured.Four hundred eighty lesions were performed. For a given target index and CF, significant differences in lesion volume and depth with different power were observed with both catheters, generally with smaller lesions using higher power. Lesions performed with CF of 10 g were particularly smaller with TactiCath compared to SmartTouch; lesions with CF of 20 g aiming a low LSI/AI were, however, bigger; lesions with CF of 20 g aiming a high LSI/AI were similar. In general, high-power lesions were wider and shallower than low-power lesions, especially with SmartTouch.Size and morphology of index-guided radiofrequency lesions varied significantly with different power and CF settings.