What is true about patent ductus arteriosus?

Can be a cause of heart failure, but may also be life-saving
Is associated with intraventricular haemorrhage, pulmonary haemorrhage, and necrotizing enterocolitis
In preterms is due to lack of endothelial cushions, hypoxia and high pulmonary resistance

PDA may produce heart failure if there is a significant left to right shunt. On the other hand, if there is an obstructive cardiac defect eg hypoplastic left heart, perfusion of the organs may be dependent on it. The direction of the shunt depends on the pressure difference between left and right: normally this will be greater on the left, but may be reversed if there is pulmonary hypertension eg due to birth asphyxia. The duct normally closes in the first week of life.