Abstract 13783: Tissue Thickness is an Essential Factor of Higher Risk of Steam Pop During Bipolar Ablation - Ex-Vivo Assessment

Abstract

Introduction/Backgrounds: For ventricular arrhythmias originating deep within the myocardium, bipolar ablation can be employed. However, there is currently no standardized strategy for bipolar ablation settings such as energy and ablation time. Hypothesis and Aims: We intended to test a hypothesis that the target tissue thickness may determine the optimal bipolar ablation settings of power and duration. Methods: Using porcine cardiac tissues ex-vivo ablation experiments were conducted. Each radiofrequency (RF) ablation catheter was placed on both sides of the myocardial slice at an angle of 45 degrees and 10g contact. We investigated the depth of ablation lesions and the occurrence of steam-pop under the multiple settings of myocardial tissue thickness, energy and ablation duration. Results: We analyzed in total 194 bipolar RF applications. For myocardial slices of 10-, 15- and 20-mm thickness, we performed 60-second RF ablation of 20, 30, 40 and 50W energy settings. No transmural lesion creation was noted on the 20-mm thickness tissues even by 50W RF energy ( Figure 1 ). Transmural lesion was observed with RF energy of 30W or more on the most of the 10-mm thickness tissues. Prolonged duration of 180 seconds with 30W or more accomplished the transmural lesion on the 15-mm thickness tissues. We observed steam-pop in 11 out of 194 applications (5.7%). Steam-pops were exclusively observed on the 10mm tissue with 30W or more. Conclusion: Our data showed that (1) transmural lesion creation for 10-mm tissue is feasible under 30W or more and 60 seconds bipolar ablation, (2) for thicker tissue even 50W application of 60 seconds may not generate transmural lesion, (3) prolonged RF duration enables transmural lesion for thicker tissues, (4) steam-pop can occur on thinner tissues under higher wattage. These results suggest that we should adapt the bipolar RF settings, particularly the power and duration depending on the target tissue thickness.