The significance of the atrial situs in the diagnosis of positional anomalies of the heart

The angiocardiograms of 29 patients with positional anomalies of the heart are presented. Dextroversion of the ventricles was present in 21, mesocardia with solitus atria in 5, and levoversion of the ventricles in 3. A normal relationship of the great vessels was observed in only 10 patients, whereas transposition was observed in 19. When the proximal connections of the great arteries could be established, corrected transposition was more common than complete transposition. Associated defects were present in 27 cases. These defects tended to be milder when the great arteries were normally related than when they were transposed. In all patients the aortic arch was situated on the same side as the morphologic left atrium. The morphology of the ventricular chambers was difficult to recognize, since both tended to be smooth walled in outline. In cases in which two ventricles were present, these chambers lay side by side. The significance of assessing the atrial situs as the basis for the recognition of positional anomalies of the heart has been stressed.