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Professor Wilkinson [email protected]
Transient pulmonary branch stenosis (PBS) in preterm and term neonates is well recognised.1-3 In preterm infants, closure of a patent ductus arteriosus (PDA) seems to be an important factor in the development of PBS,4 5 but in only one of these studies was the natural history reported. The presence of a heart murmur a few days or weeks after closure of a PDA in a preterm infant is often thought to be due to reopening of the ductus arteriosus, but the relation between a murmur and PDA is poor,6-10 and in term infants it has been shown to be more often associated with PBS than with PDA.11
The aims of this study were to (a) describe how often PBS develops in preterm infants after closure of the ductus arteriosus, (b) describe the natural history of PBS in preterm infants, and (c) determine the relation between PBS and the presence of a murmur.
Methods
Preterm infants of gestational age below 32 weeks had a full clinical examination performed by the resident paediatrician and then a complete echocardiogram performed between the second and sixth day after birth. Infants with a PDA were recruited for the study, but those with congenital heart disease were excluded. A selective echocardiogram, to study the velocity pattern across the main pulmonary artery (MPA), the right and left pulmonary arteries (RPA and LPA), as well as the size and velocity pattern across the ductus arteriosus, was then carried out on alternate days until the ductus arteriosus closed. Two further studies were carried out during the week after ductal closure. Infants who developed PBS had further selective echocardiograms performed every two weeks until discharge from hospital. If PBS was still present at discharge, the baby was followed up until PBS had resolved completely by repeat studies at a corrected age of 6 weeks, 3 months, and 6 months. All echocardiograms were performed by the same investigator (RA).
The ultrasound studies were carried out with an Acuson 128XP/10 displaying simultaneous electrocardiograms and equipped with all Doppler modalities. A gap in the atrial septum of 3 mm diameter or less was not considered to be a structural heart disease. PBS was defined as...