Heart Sound

Heart Sound


First heart sound (S1):

  • Due to closure of AV valves (mitral and tricuspid)
  • Low pitched
  • Duration: 0.14 seconds

Soft S1: 

  • Mitral stenosis (long-standing, calcified), mitral regurgitation

Loud S1: 

  • Mitral stenosis (prolonged flow through AV valve), anemia, fever, thyrotoxicosis

Second heart sound (S2):

  • Due to closure of semilunar valves (aortic, pulmonary)
  • High pitched

Wide split of S2: 

  • Atrial septal defect, mitral regurgitation, pulmonary stenosis

Reverse splitting of S2: 

  • LBBB, hypertension, aortic stenosis

Third heart 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

Fourth heart sounds (S4):

  • Low pitched
  • Pre-systolic, produced during second rapid filling phase (before S1)
  • Best heard with bell of stethoscope.
Exam Question
 

First heart sound (S1):

  • Due to closure of AV valves (mitral and tricuspid)

Soft S1: 

  • Mitral stenosis (long-standing, calcified), mitral regurgitation

Loud S1: 

  • Mitral stenosis (prolonged flow through AV valve), anemia, fever, thyrotoxicosis

Second heart sound (S2):

  • Due to closure of semilunar valves (aortic, pulmonary)

Wide split of S2: 

  • Atrial septal defect, mitral regurgitation, pulmonary stenosis

Reverse splitting of S2: 

  • LBBB, hypertension, aortic stenosis

Fourth heart sounds (S4):

  • Occurs during pre-systolic phase.
  • Produced during second rapid filling phase (before S1)
Don’t Forget to Solve all the previous Year Question asked on Heart Sound

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