Explain the Components of heart sounds?
The first major component is associated with mitral valve closure (M 1) and is due to abrupt arrest of the leaflet motion when the cusps become fully closed. It is most prominent at cardiac apex when apex is occupied by LV. The second component is thought to be due to closure of Tricuspid valve (Tl). As the mitral tricuspid closure occur 0.02 - 0.03 second apart, it is very difficult to distinguish the two. When heard, it is confined to the lower left sternal edge. Though not heard but phonocardiogram record a third component. A low frequency sound( A) following length M1 and T, and coinciding with maximum opening of aortic cusps. The usual Al occurs 0.04-0.06 second after MI. When S 1 is split, its first component is normally louder.