The Common Cardiac Ventricle with Transposition of the Great Vessels.

The physician dealing with congenital cardiac disease is not unlikely to be confronted with cases in which there is an abnormal relation between the great vessels (transposition). In analysing such a case, he attempts to determine whether or not there is some obstruction to pulmonary flow, and furthermore whether or not two ventricles are present, and, if so, which artery arises from which ventricle. At times, there is clear clinical evidence for the presence of one ventricle (common ventricle) with both great arteries arising from it. At other times, however, determination as to the existence of one or two ventricles is difficult, but whenever the two great vessels are transposed, one should suspect the presence of a common ventricle. Once this is established, either with or without pulmonary arterial obstruction, the nature of the atrio-ventricular (A-V) valves must be determined. In some cases of common ventricle there are two near-normal atrio-ventricular valves, while in others there is significant malformation of these valves: the latter malformations include common A-V valve and atresia either of the mitral or tricuspid valves.