Usefulness of epicardial impedance evaluation for epicardial mapping and determination of epicardial ablation site for ventricular tachycardia: A pilot study
During epicardial mapping, determination of appropriate ablation sites in low voltage areas (LVA) is challenging because of large epicardial areas covered by adipose tissue.1 Human epicardial fat has been reported to have higher tissue impedance than normal muscle on the epicardial surface.4 Moreover, the feasibility and accuracy of integration of computed tomography (CT)‐derived epicardial fat and magnetic resonance imaging (MRI)‐derived fat with electroanatomical maps5 have reported. However, CT or MRI imaging often cannot be performed for patients with severe chronic kidney disease or an implantable cardioverter defibrillator (ICD), which are common in patients who undergo epicardial VT ablation.
This study aimed to evaluate the impedance difference between epicardial fat and the epicardial LVA or scar using multiple detector CT (MDCT). In addition, we evaluated the magnitude of reduction of local bipolar amplitude after radiofrequency (RF) application and the characteristics of the local bipolar electrogram (EGM),9 on higher impedance sites and lower impedance sites. According to previous studies,10 local bipolar epicardial EGM characteristics differ between EGM with fat versus without fat.