Isolated total anomalous pulmonary venous drainage.

Anomalous pulmonary venous connections may provide channels for partial or for complete return of blood from the lungs to the right atrium. These are sometimes the only anomalies, but they also may be part of a complex of abnormalities. The isolated partial anomaly occurs in approximately 0.5 per cent of persons, but among patients with additional cardiovascular anomalies, partial abnormal pulmonary venous drainage is more common. About 15 per cent of patients with defects of the atrial septum requiring surgical therapy also have partial anomalous pulmonary venous connections. There are approximately 100 previously reported cases of isolated total anomalous drainage,** but only one-half as many cases of the total anomaly associated with congenital cardiac abnormalities are recorded.’ This general orientation leads to the convenient grouping of the cases of total anomalous venous drainage presented by Darling, et al.,’ based upon the level of the junction of the anomalous drainage channels with the systemic circulation.