Explain Early Diastolic Sound in diastolic ?

a) Opening snap (0s) of Rheumatic MS: High frequency sound.
Generation of sound: Because of high LA pressure, the superior systolic bowing of the anterior mitral leaflet is rapidly reversed toward; the LV in early diastole.

Best heard between apex and left sternal border.
Significance of Os:
An audible OS indicates that the mitral valve, at least the anterior mitral leaflet is mobile, not calcified.
A short A, OS interval indicates high LA pressure and therefore tight MS.
b) Early diastolic sound may be caused by atrial myxomas and is known as tumor "plop". The "plop" is due lo abrupt diastolic seating of the tumor within the right or left AV orifice.