Two Dimensional Echocardiographic Profile of Left Ventricular Outflow Tract in Transposition of the Great Arteries

MATERIALS AND METHODS: Fifty Five patients with transposition of the great arteries ranging in age from 3 months to 14 years were studied (Table-i) Two dimensional sector scans were obtained without sedation with patient in supine position. Various transducer positions were employed using an Advanced Technology Laboratories sector scanner with a 3.5 mHZ transducer. (11,12,13). The images were videotaped and stop-frame 35 mm photographs were obtained for analysis. RESULTS: Two dimensional echocardiographic and angiographic features of dynamic type of left ventricular outflow tract stenosis were noted m 8/18 patients with intact ventucular septum (Group-1). In 2 patients portions of the mitral valve were malattached into the left ventricular outflow tract and across the ventricular septal defect onto the left side of the ventricular septum. The pressure differences across the left ventricular outflow tract were 85 and 98 mm Hg. The long—axis sector scan view clearly demonstrated malattachments of the accessory or redundant mitral valve tissue to the left ventricular outflow tract and ventricular septum (Fig. 7). The normally located mitral valve was seen at the atrjoventricular annulus. One of these patients ‘underwent successful surgical repairs with Mustard opera tion and placement of the left ventricle to pulmonary artery conduit to bypass the left ventricular outflow stenosis (10), the seconi patient remains unoperated. DISCUSSION: Our experience indicates that two dimensional sector scan echocardiography is a powerful tool for visualising the left ventricular outflow tract from various planer projections. The nature of left ventricular outflow stenosis can be elucidated and its effect assessed throughout the cardiac cycle. It is concluded that 2-dimensional sector scan echocardiography is a useful tool in elucidating various forms of left ventricular outflow tract stenosis in patients with transposition of the great arteries.