After closure of the aortic and pulmonary valves(S2) , the mitral and Tricusped valve open .If the valve is stenotic , you will hear a sound on opening ( after S2) called opening snap .As the stenosis gets more severe , the LA higher pressure will force the valve to open earlier , making the opening snap closer to S2 and vice versa . If the valve became clacific , it is non pliable and this opening sound will disappear .
During flow in diastole , you will hear turbulence , that is the diastolic rumble of MS .With late diastole , the LA contracts causing presystolic accentuation of the murmur , which will disappear with AF ( no atrial contraction ) .
With lower LA pressure with severe pulmonary hypertension , or with higher LV pressure like HF or combined AS or AR , the MS murmur may be inaudible (Silent ) .
Apical diastolic rumble , with changing position , with clubbing and constitutional symptoms = LA myxoma
Apical diastolic murmer + Tricusped area diastolic murmur = combined rheumatic MS and TS or Lutembacher syndrome ( congenital MS + ASD) .
Apical diastolic rumble + early diastolic murmur of AR +hyperdynamic circulation = severe AR with Austin Flint murmur .
Isolated diastolic rumble over Tricusped area + wide fixed splitting of S2= ASD with significant shunt .