title: Dual AV nodal pathways--vagal influences on AV nodal conduction.
abstract: This 52-year-old male presented with syncope and demonstrated two distinct PR intervals on the electrocardiogram. Electrophysiologic studies showed dual AV nodal pathways. Right-sided carotid sinus massage induced prolonged periods of sinus arrest with no change in AH interval. Left-sided carotid sinus massage produced long AH intervals (slow pathway conduction) with some slowing of sinus rate. Whenever sinus rhythm with slow pathway conduction was observed (long AH) a 20-30 mmHg drop systolic pressure was seen. Following implantation of an AV sequential pacemaker, the patient has been asymptomatic.
mesh_terms: D001145:Arrhythmias, Cardiac / Q000503:physiopathology; D001283:Atrioventricular Node / Q000503:physiopathology*; D002346:Carotid Sinus / Q000503:physiopathology; D004562:Electrocardiography; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D014630:Vagus Nerve / Q000503:physiopathology*