Congenital heart lesions are notorious for their lack of characteristic signs and symptoms. The addition of venous catheterization, as developed by Cournand and Ranges (1), to the work-up of these cases presents an opportunity for the recognition of certain defects, for an estimation of the physiological magnitude of the shunts of blood, and for the study of the circulatory dynamics of these patients. Details of the procedure and methods of calculation of blood flows have been reported elsewhere (2, 3, 4, 5). Findings in representative types of congenital heart disease are herein described.2 Auricular Septal Defect In the presence of an auricular septal defect, blood usually flows from the left auricle to the right auricle. The venous catheter is helpful in the recognition of this defect by two methods, as described by Brannon, Weens, and Warren (6). The catheter may be introduced through the defect (4, 5) or arterial blood may be found in the right auricle (4). The following case report illustrates both ...