Left bundle-branch block with right axis deviation--a unique aberrancy during supraventricular tachycardia.

A tachycardia with left bundle-branch block morphology and right axis deviation points to the diagnosis of ventricular tachycardia. Conversely, any supraventricular tachycardia with left bundle-branch block is typically associated with a normal or leftward QRS axis. We present the case of a 34-year-old man showing atrioventricular nodal reentrant tachycardia with left bundle-branch block/right axis deviation as an exception to this rule.