Patent Ductus Arteriosus

Basics

Description

  • Patent vessel in the fetal heart connects the main pulmonary artery and the proximal descending aorta
  • Shifts blood away from lungs in utero
  • Normal fetal structure:
    • Typically spontaneously closes shortly after birth stimulated by sudden increase in oxygen tension
    • This results in complex cascade of changes in eicosanoids among other mechanisms
    • Subsequent contraction, closure, and fibrosis of the fetal ductus arteriosus
    • Functional closure occurs in most term infants within 24–48 hr of birth
    • Forms ligamentum arteriosum
  • In the preterm infant, persistent patency of the ductus may be a normal life-saving response
  • 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

Etiology

  • Prematurity
  • Congenital anomaly
  • Hypoxia
  • Prostaglandins

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