There is no truly curative operation for transposition of the great arteries. In our laboratory we have direct efforts towards creating an experimental model of transposition. The technique we have employed is to prepare the right ventricle of just weaned minipigs for direct switching of the aorta (with the coronaries attached) and the pulmonary artery by banding the pulmonary artery for six weeks. The banding is performed through a left thoracotomy. At the second operation the aorta is incised below the coronaries avoiding injury to the valve and then reanastomosis to the proximal end of the transected pulmonary artery is performed. The distal pulmonary artery and proximal aorta are als approximated. The procedure is done at 20 degrees C and the animal is rewarmed using pump. An ASD is made for oxygenation. Results in 18 animals have been encouraging with survival up to four hours being recorded. We hope to demonstrate the feasibility of direct anatomic correction of transposition and the physiologic implications of left ventricular "disuse" and its reversal.