This is an example of severe mitral stenosis which is most commonly due to rheumatic heart disease.
The first heart sound is decreased in intensity due to severe thickening of the mitral valve leaflets.
The second heart sound is normal and unsplit.
Systole is silent.
There is an opening snap 50 milliseconds into diastole. As mitral stenosis becomes more severe the opening snap will occur earlier in diastole.
The opening snap is followed by a low frequency murmur which occupies the remainder of diastole. The first two thirds of the murmur is diamond shaped and the remainder is a crescendo. Use the bell of the stethoscope to hear this murmur.
In the animation you can see the turbulent blood flow from the left atrium into the left ventricle. You can see the severely thickened mitral valve leaflets and the markedly enlarged left atrium. The excursion of the mitral valve leaflets is severely reduced.