Unique self-perpetuating cycle of atrioventricular block and phase IV bundle branch block in a patient with bundle branch reentrant tachycardia.

Bundle branch reentrant tachycardia (BBRT) is an uncommon form of ventricular tachycardia involving diseased bundle branches. Phase IV bundle branch block also accompanies severe His-Purkinje disease. We present an unusual case of BBRT in a patient who also manifests a unique self-perpetuating cycle of AV block and phase IV left bundle branch block following aortic valve surgery. BBRT was treated successfully by ablation of the right bundle.