Surface ECG 12 lead morphology (upper panel) and related intracavitary recording (middle and lower panels) during ventricular tachycardia caused by idiopathic right ventricular arrhythmia (IRVA). Compare with fig 3: the surface ECG pattern is indistinguishable from ARVD, but there is no diastolic activity on the intracavitary recording in this patient. Earliest activation has a lesser degree of prematurity (−30 ms) at the ablation site (96237) than in ARVD. Radiofrequency current was delivered at this site resulting in termination of ventricular tachycardia. ARVD, arrhythmia caused by right ventricular dysplasia; Mapd: mapping catheter recording, distal tip; RFCA: radiofrequency catheter ablation; RVAp, right ventricular apex electrogram, proximal tip; VT, ventricular tachycardia. ECG and intracavitary recording at 50 and 200 mm/s, respectively.