AB-452674-4 SHORT AND SWEET: EXPLORING HIGH POWER, SHORT DURATION RADIOFREQUENCY ABLATION STRATEGIES FOR OPTIMAL LESION FORMATION

Abstract

High power, short duration (HPSD) radiofrequency (RF) ablation allows for wider, more uniform ablation lesion formation as compared to moderate power, moderate duration ablation. Ablation with HPSD capitalizes on the resistive heating phase providing immediate heating to the target tissue while preventing the consequences of conductive heating. Understanding the threshold where resistive heating transitions to conductive heating may allow for optimization of parameters to favor resistive heating. Additionally, HPSD lesion application has been associated with a lower risk of complications, including cardiac perforation and atrioesophageal fistulas. To assess lesion formation with variations in RF duration and contact force utilizing a HPSD strategy in an ex vivo model. This study utilized recently harvested swine heart tissue ablated using a contact force sensing irrigation ablation catheter submerged in a saline bath with a target temperature of 36 °C and an impedance of 140 Ω. Step 1 compared various RF durations (1-5, 8, and 10 seconds(s)) with 50 Watts (W) and an average of 10g of force applied to the epicardial surface of the left ventricle. Six lesions were applied for each time duration. For step two of the procedure, we assessed the impact of contact force (1g, 5g, 10g, 20g) on lesion size and depth using 50 W and 5s RF duration. Five lesions were applied for each amount of contact force. The tissue was stained in a 2,3,5-Triphenyltetrazolium chloride bath prior to measurements. Of the 42 lesions created utilizing HPSD with variable durations of RF duration, application of >3s resulted in the creation of visual lesions within the tissue. There was an increase in lesion volume with longer duration ablation application (50W/10g), with 5, 8 and 10s durations generating lesion volumes of 16.8mm3, 26.8mm3 and 40.6mm3, respectively. All 20 lesion applications with varying degrees of contact force (50W/5s) resulted in visual lesions. There was an increase in lesion volume with higher contact force plateauing at 10 g, compared to 20g (28.9mm3 vs 31.9mm3, respectively). In an animal model, a HPSD ablation strategy focused on short duration lesion application with lower contact forces (50W/5s/10g) created lesions of similar volume to 20g of force application. In the initial 10s of lesion formation, a force >10g may have a lesser role and may potentially represent a transition point between resistive and conductive heating.