Patent Ductus Arteriosus
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- 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
- Congenital anomaly