CONGENITAL CORRECTED TRANSPOSITION OF THE GREAT VESSELS: A STUDY OF 33 CASES

Abstract

Thirty-three cases of corrected transposition of the great vessels are analyzed: 31 of corrected transposition in situs solitus, and two of corrected transposition in situs inversus. In 18 of these 33 cases, of which 64% were males, diagnosis was confirmed by necropsy or operation. There was no history of congenital heart disease in the families of any of these patients. The person whose sole anomaly is corrected transposition has no hemodynamic basis for symptoms. Symptoms are the result of associated lesions, the most common of which are anomalies of the left atrioventricular valve usually causing incompetence, ventricular septal defects, pulmonary valvular stenosis, and advanced disturbances of atrioventricular conduction. Physical findings in corrected transposition depend upon these associated defects. Noncardiac associated anomalies are rare. Anteroposterior thoracic roentgenograms may suggest the diagnosis, particularly when a narrow waist is present at the base of the heart, accompanied by the absence of a pulmonary-artery "knob" and the presence of an enlarged left atrium. Electrocardiographic features that should suggest corrected transposition are atrioventricular block (particularly 2:1 or complete heart block), abnormal P waves, absent or low R voltage in aVR, an initial Q wave in leads 3, aVR, aVF and V1, absence of a Q wave in lead V6, upright T waves across the precordium in children, and a clockwise spatial loop in the frontal plane. Cardiac catheterization may be diagnostic in this malformation when careful documentation is made of the location of the atrioventricular valves and their relation to the semilunar valves, together with the position of the great vessels in the anteroposterior and lateral views. Alteration of hemodynamics is secondary to associated malformations. Inability to enter the pulmonary artery during catheterization should arouse suspicion, and in these cases, particularly, angiocardiography can be diagnostic. The decision as to whether the most frequently associated malformations exist as isolated entities, or whether they are present in combination with corrected transposition, appears to be the main differential problem–together with the differentiation of corrected transposition with associated cyanosis from complete (that is, uncorrected) transposition. Surgical treatment of corrected transposition has been difficult because of complete atrioventricular block before or after operation, residual incompetence when deformed left atrioventricular valves were present, and the mirror-image arrangement for the coronary arteries. The most common cause of death was cardiac failure, often with a terminal bout of pulmonary edema. The average age at death in this series was about 14 years, with a median age at death of about 4 years. A review of the literature again emphasizes the association of corrected transposition with some degree of atrioventricular block evidenced on the electrocardiogram. The most frequently reported associated cardiac lesions were ventricular septal defect, pulmonary stenosis or atresia, patent ductus arteriosus, and dextrocardia. The incidence of anomalies of the left atrioventricular valve in these reported cases has probably been underestimated.