Bundle branch reentrant tachycardia treated by electrical ablation of the right bundle branch.

A 66 year old man presented with multiple episodes of tachycardia. Some had QRS complexes with a right bundle branch block configuration identical to those of sinus beats. The onset of the tachycardia was preceded by premature His bundle depolarizations. There was a His potential before each QRS complex of the tachycardia. Atrial activity was dissociated. Occasionally the appearance of sinus beats with a left bundle branch block pattern announced a tachycardia with an identical configuration and atrioventricular dissociation. His bundle activity occurred before the QRS complex and was followed by a right bundle branch deflection. A reentrant mechanism within the bundle branch system was invoked. One 200 J shock was delivered through an electrode catheter to the site of the right bundle branch. The postprocedure course was uneventful (follow-up 10 months).