[Subvalvular aortic stenosis. Apropos of 3 cases].

The three cases reported here illustrate the most frequent varieties of infra-valvular congenital aortic stenosis secondary to a fixed obstacle: such as a thin membrane located a few millimeters under the aortic ring; such as a fibro-muscular membrane at some distance of the ring; such as an infra-aortic fibro-muscular tunnel. The clinical symptoms and evolutive risks are reviewed. Ultrasound cardiography enables to make an accurate diagnosis and evaluate the associated lesions. A surgical indication is made in symptomatic forms with a gradient exceeding 40 mmHg. The advantage of early surgery is to decrease the risk of heart failure. The various surgical techniques are presented.