INDIAN PEDIATRICS 301 VOLUME 48 __ APRIL 17, 2011 P atent ductus arteriosus (PDA) is a major morbidity encountered in preterm neonates, especially in babies less than 28 weeks gestation or 1000g. Natural ductal closure is inversely related to gestational age and birth weight. The incidence ranges from 15% to 37% in newborn babies less than 1750 grams [1-3]. This is very high compared to incidence of 2/1000 in term newborns. However, this does not mean that all PDA in preterm infants are hemodynamically significant warranting treatment. Spontaneous closure of the ductus has been noticed by various researchers in up to two-third of the preterm neonates [4]. The spontaneous closure rate of ductus arteriosus is less, as well as delayed with decreasing gestation and birth weight, especially in extremely low birth weight infants [1,5]. In addition, fetal growth restriction may be associated with PDA though the evidence for the same is very limited. In a study by Rakza, et al in preterm infants of 26-32 weeks gestation, more ductus arteriosus became significant within 48 hours of birth in growth restricted as compared to eutrophic infants [11/17(65%) vs 12/31(40%); P<0.05] [6]. The role of genetic variation i.e. single nucleotide polymorphism in transcription factor AP-2, tumor necrosis factor receptor-associated factor 1, and prostacyclin synthesis may play a role in persistent patency of ductus arteriosus in preterm neonates [7]. PHYSIOLOGIC EFFECTS OF PDA The presence of PDA has significant effects on myocardial functions as well as systemic and pulmonary blood flow. Preterm newborns adapt, by increasing the left ventricular contractility, and thereby maintaining the effective systemic blood flow even when the left to right shunts equals 50% of the left ventricular output. This is mainly accomplished by an increase in stroke volume (SV) Patent Ductus Arteriosus in Preterm Infants ARUN SASI AND ASHOK DEORARI From the Division of Neonatology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110 029, India. Correspondence to: Dr Ashok K Deorari, Professor, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110 029. ashokdeorari_56@hotmail.com Patent ductus arteriosus (PDA) is a major morbidity in preterm infants, especially in extremely premature infants less than 28 weeks. The clinical signs and symptoms of PDA in preterm infants are non specific and insensitive for making an early diagnosis of significant ductal shunting. Functional echocardiography is emerging as a new valuable bedside tool for early diagnosis of hemodynamically significant ductus, even though there are no universally accepted criteria for grading the hemodynamic significance. Echocardiography has also been used for early targeted treatment of ductus arteriosus, though the long term benefits of such strategy are debatable. The biomarkers like BNP and N- terminal pro–BNP are currently under research as diagnostic marker of PDA. The primary mode of treatment for PDA is pharmacological closure using cyclo-oxygenase inhibitors with closure rate of 70-80%. Oral ibuprofen is emerging as a better alternative especially in Indian scenario where parenteral preparations of indomethacin are unavailable and side effects are comparatively lesser. Though pharmacological closure of PDA is an established treatment modality, there is still lack of evidence for long term benefits of such therapy as well as there is some evidence for the possible adverse effects like increased ROP and BPD rates, especially if treated prophylactically. Hence, it is prudent to reserve treatment of PDA to infants with clinically significant ductus on the basis of gestation, birth weight, serial echocardiography and clinical status to individualize the decision to treat. Key words: Functional echocardiography, Ibuprofen, Indomethacin, Patent ductus arteriosus, Preterm infant. R E V I E W R E V I E W R E V I E W R E V I E W R E V I E W ARTICLE