Patent ductus arteriosus (PDA) is a common diagnosis in preterm infants, especially, in extremely preterm infants. PDA is extremely important during the fetal life. After birth, functional closure of this vessel occurs during the first 72 hours in majority of the late preterm and term infants. However, in preterm infants, due to higher sensitivity to prostaglandins, predominance of vasodilator receptors in the ductal tissue, and lack of vasa vasorum, ductus arteriosus (DA) may not close spontaneously or often remains patent for weeks. Incidence of PDA correlates inversely with gestational age. Routine use of echocardiography in the neonatal intensive care unit has led to increase in the diagnosis of even small or hemodynamically non-significant PDA.
Hemodynamic effects of a PDA depend on several factors, such as, size and direction of shunt across the DA, extent of steal phenomena, adequacy of compensatory mechanisms and duration of patency of DA. Prolonged patency of DA has been shown to be associated with several morbidities, like, bronchopulmonary dysplasia, intraventricular hemorrhage, retinopathy of prematurity, necrotizing enterocolitis, and increase in mortality.
Typically, clinicians tend to treat “hemodynamically significant PDA” (hsPDA) with non-selective cyclooxygenase inhibitors, like, ibuprofen or indomethacin, or peroxidase inhibitor, paracetamol. Success with any of these drugs is about 70%. When medical treatment fails, surgery is often used to close the PDA. Surgical ligation of PDA is associated with post-ligation cardiac dysfunction, and pulmonary dysfunction leading to increase in oxygen and ventilatory requirements. Furthermore, surgical ligation has been associated with vocal cord paralysis, phrenic nerve injury, and abnormal neurodevelopmental outcomes. In the present era, transcatheter closure of PDA is increasingly being evaluated in many leading centers to minimize complications associated with surgical ligation. Assessment using multiple echocardiographic indices including organ blood flow by Doppler rather than just the size of DA is much more helpful in making a decision to treat or just follow the PDA. In cases of hsPDA that failed to respond to medical interventions, device closure should be considered first if patients meet the eligibility criteria for device closure before surgical ligation.
Division Chief, Division of Neonatal Medicine, LAC+USC Medical Center
Good Samaritan Hospital
Director, NPM Fellowship Program and NICU
Director, Neonatal Respiratory Therapy Services
Keck School of Medicine of USC
Los Angeles, California, USA