title: Mechanism of influence of PR interval on loudness of first heart sound.
mesh_terms: D000328:Adult; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000502:physiology*; D006326:Heart Auscultation; D006347:Heart Sounds; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000502:physiology*; D009200:Myocardial Contraction; D010701:Phonocardiography