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Completed - Normal Second heart sound

The most difficult thing in auscultation is to identify the abnormalities of S2.

Physiology of Second heartsound

Two components for 2nd heart sound are- aortic and pulmonary
Aortic component it is the 1st component and loud one   heard in all areas
Pulmonary component - 2nd component and soft, heard only over pulmonary area.

Normal second heart sound
  1. It is a high pitched sound with normal split - 2 components are separately heard during inspiration and as single component during expiration over the pulmonary area.
  2. Distance between the 2 components during inspiration is 0.04 sec, during expiration is 0.02 sec. 
  3. Human ear can appreciate, when the distance between the 2 components is 0.03 or more. 
  4. Normal second heart sound is expressed as - normal in intensity and normal split with respiration.
Things to look for in S2:
A2 heard over aortic area and pulmonary area and the apex.
P2 heard over pulmonary area and 2-4 LICS only and not at the apex.
P2 heard over the apex only in pulmonary artery hypertension and in young.
Best site for S2 in COPD—epigastrium