[Collateral pulmonary circulation in Fallot's tetralogy].

An angiographic study of 231 patients with tetralogy of Fallot (TOF) in both neonatal and adult age groups (0 to 49 years) was in this condition. Cases of pulmonary atresia with ventricular septal defect were excluded. Two types of collateral pulmonary circulation were observed: the most common form is the result of distal intrapulmonary anastomosis between systemic parietal, mammary and bronchial vessels with the pulmonary arteries. This type of collateral circulation represents an evolutive stage of TOF and is directly related to age and to the degree of hypoxia; the other, oa rare and probably congenital form (1.7 p. 100 of cases) observed even in young children, consisting of proximal anastomoses between systemic vessels arising from the aorta (1 to 3 vessels) and the pulmonary arterial tree. The rare forms of TOF with single pulmonary arteries acquired after palliative or congenital anastomoses (1.4 p. 100) have both types of collateral circulation. Preoperative diagnosis of the collateral pulmonary circulation requires opacification of the aorta especially of the descending thoracic segment and its branches, completed in cases of an absent pulmonary artery by wedged pulmonary venous opacification. The haemodynamic effects of this collateral circulation on the pulmonary bed to a variable degree of histological change. This may partially explain some of the poor surgical results of repair of TOF and, in view of recent progress in cardiopulmonary bypass techniques in children, incite to earlier surgical correction of this condition.