Explain Components of second heart sounds?
The first component of S2 is due to closure of aortic valve (A,). The second component is due to closure of pulmonary valve (P2). Normally A, is louder whereas P, is soft, reflecting the difference in systemic and pulmonary arterial closing pressure. The softer P, is normally confined to 2nd left ICS whereas the louder A, is heard at base, sternal edge and apex.