Figure 23i

Transposition and Switching of the Great Arteries.
In D-transposition of the great arteries (complete transposition)(Panel A), systemic venous blood returns to the right atrium, from which it goes to the right ventricle and then to the aorta. Pulmonary venous blood returns to the left atrium, from which it goes to the left ventricle and then to the pulmonary artery. Survival is possible only if there is a communication between the two circuits, such as a patent ductus arteriosus. With the "atrial switch" operation(PanelB), a pericardial baffle is created in the atria, so that blood returnig from the systemic venous circulation is directed into the left ventricle and then the pulmonary artery (blue arrow), whereas blood returning from the pulmonary venous circulation is directed into the right ventricle and then the aorta (red arrow). With the "arterial switch" operation (Panel C), the pulmonary artery and the ascending aorta are transected above the semilunar valves and the coronary arteries, then switched (neoaortic and neopulmonary valves).