Patent Ductus Arteriosus



  • Patent vessel in the fetal heart connects the pulmonary trunk to the descending aorta
  • Shortly after birth, changes normally provoke contraction, closure, and fibrosis:
    • Sudden increase in the partial pressure of oxygen
    • Changes in the synthesis and metabolism of vasoactive eicosanoids
  • In the preterm infant, persistent patency of the ductus may be a normal life-saving response
  • The patent ductus usually has a normal structural anatomy
  • Patency results from hypoxia and immaturity
  • In the full-term newborn, patency of the ductus is a congenital malformation
  • Deficiency of both the mucoid endothelial layer and the muscular media of the ductus
  • As pulmonary vascular resistance falls, aortic blood is shunted into the pulmonary artery
  • Extent of the shunt reflects the size of the ductus and the ratio of the pulmonary to systemic vascular resistances
  • Up to 70% of the left ventricular output may be shunted through the ductus to the pulmonary circulation
  • Risk factors:
    • Premature birth
    • Coexisting cardiac anomalies
    • Conditions resulting in hypoxia
    • High altitude
    • Maternal rubella infection
    • Female-to-male ratio, 3:1


  • Prematurity
  • Congenital anomaly
  • Hypoxia
  • Prostaglandins

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