Abstract 15070: Predicting Steam-Pop Incidence Using Ex-Vivo Bipolar Ablation Model of Porcine Ventricular Myocardium

Abstract

Introduction: Bipolar ablation has been reported to be able to create deep myocardial ablation lesion as compared to unipolar ablation, however, the incidence of steam-pop can lead to undesirable periprocedural complication. Hypothesis: Steam-pop occurrence during bipolar ablation can be predicted by the settings of bipolar ablation and the myocardial tissue characteristics such as tissue thickness and initial impedance prior to RF. Methods: Using porcine cardiac tissues ex-vivo ablation experiments were conducted. We adopted the commercially available radiofrequency (RF) ablation catheters. Each ablation catheter was placed on both sides of the myocardial slice at an angle of 45 degrees under targeted contact force of 10g. We recorded the occurrence of steam-pop under the multiple settings of tissue thickness, RF power and ablation duration. We created a generalized linear model (GLM) to predict steam-pop based on the bipolar ablation settings and the myocardial tissue characteristics. Results: In total 194 bipolar applications were analyzed. Steam-pops were observed in 11 out of 194 applications (5.7%). In the applications with steam-pop, the RF energy was higher (median 40W [q1-q3: 30-50] vs 30W [20-40], P=0.017), the initial impedance was lower (88 [86.75 - 91.5] vs 93 Ohm [89.75 - 95.75], P=0.0042) and the tissue thickness was thinner (9.4 [8.43 - 9.89] vs 12.9 mm [10.06 - 15.47], P<0.0001) as compared to the applications without steam-pop. Using tissue thickness, RF energy and initial impedance, the constructed GLM achieved sensitivity of 100%, specificity of 93% and the area under the receiver-operator-characteristics curve of 0.969. Conclusion: Our data showed that the steam-pop occurrence during bipolar ablation may be predicted based on the initial RF settings and the tissue characteristics in the ex-vivo porcine myocardial model. Further studies are necessary to validate the feasibility of predicting steam-pops using the RF and tissue characteristics in the beating heart and human heart, which may enable us to titrate the RF settings and lead to safer bipolar ablation.