title: The initial component of the first heart sound.
mesh_terms: D000328:Adult; D001281:Atrial Fibrillation / Q000175:diagnosis*; D006801:Humans; D008944:Mitral Valve Insufficiency / Q000175:diagnosis*; D008946:Mitral Valve Stenosis / Q000175:diagnosis*; D010701:Phonocardiography