Bidirectional ventricular tachycardia with alternating right and left bundle branch block morphology in a patient with metastatic cardiac tumors.

A case is reported of bidirectional ventricular tachycardia and syncope in a 16-year-old male with a previous history of a paratesticular rhabdomyosarcoma that achieved complete remission with treatment. At the electrophysiological study, frequent ectopy of both right and left bundle branch block pattern were present, with runs of monomorphic and bidirectional VT alternating the two morphologies. The study suggested a single focus at the interventricular septum with two exit sites, depolarizing the right and left ventricle in an alternate fashion. Reassessment of the malignancy status showed multiple cardiac metastases with a 4 mm nodule at the interventricular septum.