title: 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.
mesh_terms: D001145:Arrhythmias, Cardiac / Q000503:physiopathology; D001281:Atrial Fibrillation / Q000503:physiopathology; D001283:Atrioventricular Node / Q000503:physiopathology*; D002036:Bundle of His / Q000503:physiopathology*; D002037:Bundle-Branch Block / Q000503:physiopathology*; D004558:Electric Stimulation; D004562:Electrocardiography; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D013577:Syndrome; D013614:Tachycardia, Paroxysmal / Q000503:physiopathology*