An atrial septal defect is commonly thought of as a benign cardiac lesion e
specially in infancy. The haemodynamic consequences for the lungs, nonethel
ess, can be comparable to that produced by patency of the arterial duct. In
a preterm boy, this lesion led to the development of broncho-pulmonary dys
plasia, and dependence on a respiratory ventilator. He could be extubated s
hortly after surgical closure of the septal defect.