Plasma brain natriuretic peptide as a predictor of haemodynamically significant patent ductus arteriosus in preterm infants.

Patent ductus arteriosus (PDA) is an important cause of morbidity in extremely preterm infants. As increased plasma brain natriuretic peptide (BNP) is a common feature of adult cardiac disease, we investigated the value of plasma BNP concentration as a predictor of haemodynamically significant PDA in very preterm infants. We studied 18 preterm infants (12 male) of median gestational age 30 weeks (range 24-34), median birth weight 1.46 kg (0.54-2.13) and 11 healthy term controls. Plasma BNP levels were measured by double-antibody radioimmunoassay on days 3, 5 and 7 of life, and an echocardiogram was performed on day 7. Six infants of median gestation 26 weeks (26-30), median birth weight 0.92 kg (0.54-1.04) had PDA proven by echocardiography on day 7. BNP concentrations (pg/ml) on day 3 were significantly higher in these infants than in the remaining twelve [median 2012 (786-2759) versus 42 (7-704), P<0.001]. In four infants PDA was treated successfully (one surgically, three with non-steroidal anti-inflammatory drugs). Two had haemodynamically insignificant closing ducts. In these infants with therapeutic or spontaneous resolution of a PDA, plasma BNP fell to normal values [median after treatment 9 pg/ml (8-27)]. Early measurement of plasma BNP in the first few days of life is a useful method for predicting those preterm infants who may require intervention for PDA.