Case 33

Aortic Stenosis

Etiology

Isolated stenosis of the aortic valve is most commonly secondary to congenital bicuspid valve. Rheumatic heart disease is another important cause of aortic stenosis.

Imaging Features

Mild-to-moderate aortic stenosis can cause left ventricular hypertrophy. The left ventricular border may be rounded, or the cardiac apex may be elevated secondary to concentric left ventricular hypertrophy. More severe valvular stenosis can lead to enlargement of the left ventricle and atrium and to hypertrophy. The ascending aortic contour bulges rightward secondary to poststenotic dilation (Fig. A). Calcification of the valve can develop as a result of degeneration and can be seen on CT or, when severe, on chest radiographs (Fig. B).

Quantification

The pressure gradient across the valve can be calculated by use of the modified Bernoulli equation: ΔP = 4v², where P is the pressure in mm Hg and v is peak velocity in m/s. The peak velocity can be estimated by echocardiography or velocity-encoded cine phase contrast MRI.