PubMed1980
Three patients with corrected transposition of the great arteries (CTGA) have been studied by means of single plane (M-mode) and two-dimensional (2-D) echocardiography: the first study was performed after surgical closure of a VSD and the remaining two before cardiac catheterization. The following M-mode findings can suggest the diagnosis in CTGA: the interventricular septum (IVS) may not be visualized, there is lack of continuity between the posterior a-v valve (tricuspid) echoes and the anterior great artery (aorta), the posterior a-v valve leaflets may show some abnormalities in shape. The measurement of systolic time intervals of both semilunar valves can help in distinguishing the pulmonary artery from the aorta; further information can be obtained by means of peripheral venous contrast injection, which, in absence of right-to-left shunt, opacifies the posterior great vessel (pulmonary). The 2-D view of the heart allows the identification of the morphological type of ventricle and of the spatial great arteries relationship. The posteriorly and left located ventricle is recognized as morphologically right, because of the tricuspidal shape of its a-v valve: its attachment to IVS is lower than that of the mitral valve (4-chambers view) and three leaflets may be evident (short-axis); 3 papillary muscles and gross trabeculations can be identified (short axis and 4-chambers views, respectively). In long-axis the anterior vessel (aorta) runs parallel to the sternum; in short-axis both vessels are imaged as adjacent circles; by means of peripheral contrast injection, in conditions without right-to-left-shunt, the right and posterior vessel is recognized as a pulmonary artery. The differential diagnosis is discussed with d-transposition, Fallot's tetralogy, Taussig-Bing anomaly, common trunk, univentricular heart. According to our experience, the diagnosis of CTGA and associated defects can be made by M-mode and 2-D echocardiography.