In severe aortic stenosis, a diamond-shaped systolic murmur is present throughout systole. This murmur is louder and higher-pitched than a mild aortic stenosis murmur. Calcification of the aortic valve leaflets produces this murmur.
A fourth heart sound occurs in late diastole, immediately before S1. Increased left ventricular wall thickness/stiffness produces this fourth heart sound.
S1 is normal, while S2 is louder than normal. Note that only an accentuated pulmonic component of S2 can be heard. This S2 abnormality is caused by left-side heart failure.
The aortic ejection click, heard in mild cases of valvular aortic stenosis, is not present.
Observe the significantly thickened left ventricular wall and the near-totally immobile aortic leaflets in the cardiac animation video.
Listen

The patient's position is sitting.