Total anomalous pulmonary venous connection (TAPVC) is failure of development of the common pulmonary vein, with consequent ersistence and enlargement of embryonic collaterals between the lungs and the systemic veins. In the great majority (91 of 93 autopsied cases, 97 per cent, no remnant of the common pulmonary vein was found, supporting the concept of agenesis or involution of the common pulmonary vein. Occasionally, a cordlike strand was found in the location of the common pulmonary vein (in three of 93 cases, 3 per cent), supporting the concept of atresia of the common pulmonry vein. The order of frequency of the various types of TAPVC was: left innominate vein ("snowman"), 26 perent cent; subdiaphragmatic, 24 per cent; coronary sinus, 18 per cent; right superior vena cava, 15 per cent; right atrium, 8 percent; mixed, 5 per cent; azygos, 2 per cent; and left supeior vena cava, 2 per cent...