The first heart sound in normal and ectopic ventricular contractions; mechanism of closure of the A-V valves.
D006337:Heart Murmurs; D006347:Heart Sounds; D006351:Heart Valves / Q000502:physiology*; D006801:Humans; D018879:Ventricular Premature Complexes
CARDIAC MURMURS AND SOUNDS; CARDIAC VALVES/physiology