<prompt> Which of the following is a high pitched sound: March 20111st hea soundTumour plopOpening Snap4th hea sound  <response>: Ans. C: Opening snap The opening snap OS is a brief, high-pitched, early diastolic sound, which is usually due to stenosis of an AV valve, most often the mitral valve First hea sound S1: Due to closure of AV valves mitral and tricuspid Low pitched Duration: 0.14 seconds Soft 51: Mitral stenosis long standing, calcified, mitral regurgitation Loud Si: Mitral stenosis prolonged flow through AV valve, anemia, fever, thryotoxicosis Second hea sound S2: Due to closure of semilunar valves aoic, pulmonary High pitched Wide split of S2: Atrial septal defect, mitral regurgitation, pulmonary stenosis Reverse splitting of S2: LBBB, hypeension, aoic stenosis Third hea sound S3: Due to ventricular filling Low pitched Diastolic, occurring after S2 Best heard at apex with the bell of stethoscope Causes: Children, hyperdynamic states, left ventricular failure, right ventricular failure Fouh hea sounds S4: Low pitched Pre-systolic, produced during second rapid filling phase before S1 Best heard with bell of stethoscope Seen in: Hypeension, aoic stenosis, HOCM, acute mitral regurgitation 