[Two-dimensional echocardiography in subvalvular aortic stenosis. Apropos of 20 cases].

Twenty cases of discrete subvalvular aortic stenosis in children aged from 8 months to 23 years were examined by 2-dimensional echocardiography and cineangiography. Fifteen of these patients subsequently underwent open heart surgery to relieve the obstruction. In 18 cases the obstacle was a fixed stenosis (13 type I, 3 type II and 2 type III) and in two cases, the obstacle was provoked by accessory tissues of the anterior mitral leaflet. The echocardiographic incidences used were the left parasternal long axis, the apical LAO-equivalent, and longitudinal and transverse subcostal views. In type I, fixed subvalvular stenosis, one fine abnormal echo was visualised in the left ventricular outflow tract throughout the cardiac cycle immediately below the aortic valve, best seen on apical views. Twelve of the 13 stenoses of this type were demonstrated by 2D echocardiography. In type II stenosis an abnormal thickened echo was visualised in the left ventricular outflow tract at a distance from the aortic cups. The adherence of this abnormal echo to the anterior mitral leaflet was best demonstrated by apical views. All three cases of this type were demonstrated by echocardiography. Type III stenosis was characterised by widespread narrowing of the subaortic region with irregular borders. Obstruction due to accessory tissues of the anterior mitral leaflet were well demonstrated in left parasternal long axis and apical views. They showed an even rounded mass of echos attached to the anterior aspect of the anterior leaflet prolapsing into the left ventricular outflow tract. Both cases in this series were diagnosed by 2D echocardiography. Therefore, 2D echocardiography with apical and subcostal views is a valuable method for diagnosing subvalvular aortic stenosis and for determining its anatomical type.