Intermittent bundle branch block in patients with accessory atrio His or atrio AV nodal pathways. Variants of the Lown Ganong Levine syndrome

Abstract

Intracardiac electrophysiological studies were performed in two patients with a documented history of repetitive supraventricular tachyarrhythmias. Case 1, with short PR interval and narrow QRS complexes, had a short AH interval and intermittent right bundle branch block. Thus the short PR wide QRS syndrome is not always a result of the Wolff Parkinson White syndrome but can also be seen in the Lown Ganong Levine syndrome coexisting with bundle branch block. Case 2, with normal PR and AH at the lower limits of normal, showed the dual pathway response to atrial pacing that can occur in patients with Lown Ganong Levine syndrome. He also had tachycardia dependent right bundle branch block and left posterior hemiblock. Therefore, neither the short PR interval nor the narrow QRS complexes characterized these forms of pre excitation. The constant features were, from the clinical viewpoint, the occurrence of repetitive supraventricular tachyarrhythmias, and electrophysiologically the abnormal response to atrial stimulation.