Abstract 19004: Contact Force Recovery Predicts Absence of Cardiac Perforation During Steam Pop Formation

Introduction: Cardiac perforations (CP) are an uncommon complication of radiofrequency ablation (RFA) that has profound clinical importance. We previously published results showing that the presence of contact force recovery after a steam pop occurs can be used to predict the absence of perforation in the absence of pericardium. Now, we aimed to determine if this relationship exists with the pericardium present, validate our results from the previous study, and determine the effects pericardium has on RFA. Methods: A 7.5F Thermocool Smarttouch force-sensing catheter (Biosense Webster Inc., Diamond Bar, CA) was used to perform left atrial RFA under direct observation in five open-chest sheep. The catheter’s contact force was measured every 50 ms during RFA. After each steam pop, the presence (+) or absence (-) of CP was noted as well as if pericardium was present or not over the ablation site. The contact force signals were then analyzed to determine if contact force recovery was present. In addition, the rate of perforation in the presence or absence of pericardium was also compared. Results: A total of 86 steam pops occurred (Table 1); 62 with pericardium and 24 without pericardium. For the pericardial data, contact force recovery was seen in 16 of the 49 CP- cases (33%) and 0 of the 13 CP+ cases (0%), p = 0.03. For the nonpericardial data, contact force recovery was seen in 6 of the 14 CP- cases (43%) and 0 of the 10 CP+ cases (0%), p = 0.02. The rate of cardiac perforation was 21% with pericardium and 42% without, p = 0.05. Pericardial tissue showed extensive charring during steam pops, even in the absence of CP. Conclusions: Contact-force recovery predicts the absence of CP during RFA independent of the presence or absence of the pericardium, confirming prior work. Our results suggest the pericardium decreases the likelihood of perforation, perhaps by acting as a thermal sink. Further studies are needed to correlate these results with clinical experiences.