The natural course of supravalvar aortic stenosis and peripheral pulmonary artery stenosis in Williams's syndrome.

The haemodynamic findings from two serial cardiac catheterisations in ten patients with Williams's syndrome were reviewed. The median ages at study were one and nine years. Raised mean (SD) left ventricular peak systolic pressures associated with supravalvar aortic stenosis increased significantly with time from 121 (25) mm Hg to 153 (29) mm Hg. The peak systolic pressure drop between the left ventricle and aorta (measured in seven patients) increased significantly from 25 (25) mm Hg to 50 (35) mm Hg. Raised right ventricular peak systolic pressure associated with peripheral pulmonary artery stenosis (in eight patients) decreased significantly with time from 52 (26) mm Hg to 28 (6) mm Hg. Supravalvar aortic stenosis in Williams's syndrome seems to progress rapidly, and careful monitoring is indicated. There is a strong likelihood that peripheral pulmonary artery stenosis in Williams's syndrome will improve spontaneously with time.