Patent Ductus Arteriosus

Basics

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

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