Definition

A patent ductus arteriosus (PDA) in the first 3 days of life is a physiological shunt connection (PA – aorta) in healthy term and preterm newborn infants. In contrast, a persistently patent ductus arteriosus in preterm infants can become a clinical problem, e.g., during the recovery period from respiratory distress syndrome (RDS). With the improvement of ventilation and oxygenation, pulmonary vascular resistance (PVR) decreases early and rapidly (starting within the first hours of life), especially in preterm infants <1000 g (ELBW). Subsequently, the left-to-right shunt through the ductus arteriosus (aorta → DA → PA) and optionally the patent foramen orale (PFO) (RA → LA) increases, as does the pulmonary blood flow, leading to (interstitial) pulmonary edema and overall worsening of respiratory status. PDA of the preterm infant is frequently not symptomatic before day 4 of life.

Epidemiology

• 31% of preterm infants with a birth weight (BW) of 501–1500 g have a PDA

• A significant PDA associated with heart failure is found in 15% of preterm infants weighing less than 1750g

• A significant PDA that may require treatment during the neonatal period occurs in approximately 60% of preterm infants weighing less than 1000 g

Etiology/pathophysiology

In term neonates, a postnatal increase in PaO2 and a decrease in prostaglandin E (PGE), nitric oxide (NO), and other vasodilator substances induces constriction of ductal vascular smooth muscle cells and consequently functional closure of the ductus.