[An application of X-ray computed tomography for complex cardiac anomalies]

X-ray computed tomography (CT) was performed in two patients with complex congenital heart disease in order to assess the clinical utility in the systemic morphological diagnosis. A Somotom 2 whole body CT scanner (Siemens Co) was used, and contrast enhanced CT scanning and a dynamic CT scanning were performed in one case (Case 2).; Case 1: A 20-year-old female with double outlet right ventricle (S, D, L), pulmonary stenosis and aortic insufficiency. The CT revealed a viscero-atrial situs, ventriculoarterial relation, spatial interrelationship between the great arteries and a run of the stenotic pulmonary artery. The CT clarified spatial relationship among four cardiac chambers, ventricular septal defect and great arteries, contributing to the understanding of the complex cardiac structure. Case 2: A 26-year-old female with single ventricle (III-C solitus), pulmonary stenosis, dextroversion, left superior vena cava and WPW syndrome. The CT documented precisely a viscero-atrial situs, dextroversion, ventriculoarterial relation, spatial interrelationship between the great arteries, stenotic main and left pulmonary arteries and a dilated right pulmonary artery due to the right Blalock-Taussig operation performed 15 years before. A diagnosis of left superior vena cava could be made by CT, and its flow into coronary sinus was visualized by dynamic CT. The dynamic CT also clarified a mixing of venous and arterial blood in the common ventricle, and revealed a rudimentary ventricular septum. Thus, the CT serves useful purposes especially as examination of viscero-atrial situs, ventriculoarterial relation and spatial interrelationship between great arteries, and anomalies of the mediastinal vessels. Furthermore the relationship among four cardiac chambers, ventricular septal defect, and the pattern of blood flow were also clarified. However, the CT failed to define the state of a ventricular loop, because it could not identify ventricular muscular structures and atrioventricular valves as these move rather vigorously. The CT could not locate pulmonary stenosis, valvular or somewhere else. The CT seemed to be a promising noninvasive method in the systemic morphological diagnosis of congenital heart disease as subsidiary to echocardiographic investigation. However, in pediatric patients, it seemed considerably hard to obtain clear cardiac CT images because of the difficulty in halting respiration during procedure.