title: Vagally induced second degree A-V block Mobitz type I, and the hyporeactive SA node.
mesh_terms: D000293:Adolescent; D000328:Adult; D004562:Electrocardiography; D005260:Female; D006327:Heart Block / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D012849:Sinoatrial Node / Q000503:physiopathology*; D014630:Vagus Nerve / Q000503:physiopathology*; D014636:Valsalva Maneuver