Bundle branch re-entry ventricular tachycardia in a patient with myotonic dystrophy.

Bundle branch re-entry (BBR)-ventricular tachycardia (VT) is relatively rare with an incidence of about 6% in sustained monomorphic VT series. However, physicians unexpectedly encounter it in clinical practice. BBR-VT is associated with serious hemodynamic decompensation, and the clinical presentation in approximately 75% of patients with inducible BBR-VT is syncope or cardiac sudden death. Thus, precise mapping of His-Purkinje and bundle branch potentials is necessary for an accurate diagnosis and treatment of re-entrant mechanisms especially for BBR-VT. However, simultaneous recording of both the left-bundle (LB) and right-bundle (RB), as well as His-bundle (HB), potentials is often difficult during tachycardia. Here we report the clear documentation of the activation sequence of the His-Purkinje system during BBR-VT, which could be readily and completely treated by radiofrequency catheter ablation in a myotonic dystrophy patient.