title: Vagal tone, significance of electrophysiologic findings and clinical course in symptomatic sinus node dysfunction.
mesh_terms: D000368:Aged; D001146:Arrhythmia, Sinus / Q000150:complications / Q000503:physiopathology*; D001285:Atropine; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012849:Sinoatrial Node / Q000503:physiopathology; D013575:Syncope / Q000209:etiology; D014630:Vagus Nerve / Q000503:physiopathology*
chemical_list: D001285:Atropine