Background-Efficacy of endocardial ventricular tachycardia (VT) ablation in arrhythmogenic right ventricular cardiomyopathy/dysplasia may be limited by epicardial VT, right ventricular thickening, or both. We sought to characterize the endocardial versus epicardial substrate, measure right ventricular free wall thickness, and determine epicardial ablation efficacy in patients with right ventricular cardiomyopathy/dysplasia. Methods and Results-Thirteen consecutive patients (3 female; aged 43Ϯ15 years; range, 17 to 70 years) undergoing endocardial and epicardial sinus rhythm voltage mapping and epicardial VT ablation after failed endocardial VT ablation were included. In each patient, the low bipolar voltage area (Ͻ1.0 mV for epicardium and Ͻ1.5 mV for endocardium) was more extensive on the epicardium (95Ϯ47 versus 38Ϯ32 cm 2 ; PϽ0.001) and was uniformly marked by multicomponent and late electrograms. The basal right ventricular thickness assessed by electroanatomic map was Ͼ10 mm in 6 of 13 patients compared with 5 to 10 mm in 4 reference patients without structural disease. Twenty-seven VTs were targeted on the epicardium with the use of activation, entrainment, or pace mapping with focal/linear ablation and targeting of late potentials. Epicardial VTs were targeted opposite normal endocardium in 10 patients (77%) and/or opposite ineffective endocardial ablation sites in 11 patients (85%). During 18Ϯ13 months, 10 of the 13 patients (77%) had no VT, with 2 patients having only a single VT at 2 and 38 months, respectively. Conclusions-Patients

Using the described techniques, PV electrical isolation of PVs demonstrating spontaneous and/or provoked triggers is superior to focal PV ablation, with marked differences in outcome by 2 months. MEAM confirmed the noncircumferential nature of ostial ablation for effective isolation of most PVs and may play a role in the low risk and good outcome observed. The good outcome of targeted PV isolation as described suggests the need for a prospective comparison of targeted versus empiric PV isolation techniques.

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Catheter-based radiofrequency ablation in the left heart can provide effective therapy for tachyarrhythmias. The recent development of the real time intracardiac echocardiography (ICE) with 2D and Doppler color flow imaging can facilitate left heart ablation procedures. This report reviews the use of ICE during radiofrequency catheter ablation procedures for atrial fibrillation (AF) and ventricular tachycardia and is based on our own experience in 955 patients. ICE has a critical role for guiding transseptal catheterization, assisting placement of mapping/ablation catheters and monitoring lesion morphologic changes, especially in the pulmonary vein ostia, Marshall ligament region, thickened interatrial septum, left atrial posterior wall contiguous to esophagus, aortic valve cusps, and the epicardial regions. One of the more powerful utilities of ICE lies in its ability to identify and potentially reduce procedural complications including damage to intracardiac structures, residual atrial septal defect, left atrial thrombus formation, pulmonary vein stenosis, esophageal injury, myocardial air-embolization and pericardial effusion during left heart ablation.