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We successfully performed radiofrequency catheter ablation (RFCA) in 2 cases involving patients with idiopathic ventricular tachycardias (VTs) and premature ventricular contractions (PVCs) originating from the pulmonary artery (PA). The QRS morphology of the VTs and PVCs in the two cases exhibited a left bundle-branch block (LBBB) morphology with an inferior axis. Activation and pace mappings were performed in the right ventricular outflow tract (RVOT) and above the pulmonary valve to determine the origin of the VTs and PVCs. In both cases, the earliest ventricular activation was recorded in the PA above the pulmonary valve. Applications of radiofrequency current at those sites in the PA resulted in the elimination and noninducibility of the VT and PVC. During the follow-up, the VT or PVC did not recur without any antiarrhythmic drug administration.

A 49-year-old male was referred to the hospital because of syncope caused by ventricular tachycardia (VT) with a pulse of 240 bpm and QRS morphology with a LBBB configuration and superior axis. The patient had been on a long-term regimen of steroids to treat his scleroderma. Satisfying 2 major criteria (QRS widening and an epsilon wave in the right chest leads) and 3 minor criteria (a slight enlargement and akinesis of the right ventricle, positive late potential in the signal averaged electrocardiogram and left bundle branch block-type VT) he was diagnosed with arrhythmogenic right ventricular cardiomyopathy. A voltage map of his right ventricle (RV) during sinus rhythm was obtained using an electroanatomical mapping system (CARTO, Biosense-Webster, Diamond, CA, USA). Two islet-like low voltage areas were found and linear double potentials were recognized between areas in the lateral wall of the right ventricle (RV) very close to the tricuspid annulus. The earliest activation of the double potential line during VT was 70 msec prior to the QRS onset. We applied radiofrequency energy at that point during the VT and it successfully slowed and terminated the VT. Thereafter the VT could not be induced by any stimulation from multiple RV sites.