Patent ductus arteriosus and the risk of bronchopulmonary dysplasia-associated pulmonary hypertension.

Background: The aim of the study was to determine whether prolonged exposure to a moderate/large patent ductus arteriosus left-to-right shunt (PDA) increases the risk of late (beyond 36 weeks) pulmonary hypertension (BPD-PH) and pulmonary vascular disease (BPD-PVD) during the neonatal hospitalization in preterm infants (<28 weeks' gestation) with bronchopulmonary dysplasia (BPD).

Methods: All infants requiring respiratory support ≥36 weeks had systematic echocardiographic evaluations for BPD-PH at planned intervals. Infants were classified as having either flow-associated BPD-PH (BPD-flow-PH) or BPD-PVD.

Results: 256 infants survived ≥36 weeks: 105 had NO BPD (were off respiratory support by 36 weeks); 151 had BPD. 22/151 had BPD-PH (12/22 had BPD-flow-PH from a PDA that persisted beyond 36 weeks; 10/22 had BPD-PVD). Moderate/large PDA shunts that persisted beyond 36 weeks were significantly associated with an increased incidence of BPD-PH due to BPD-flow-PH. We found no association between the duration of PDA exposure and the incidence of BPD-PVD.

Conclusions: Moderate/large PDA shunts increase the risk of flow-associated BPD-PH when present beyond 36 weeks. Although term infants with PDA-congenital heart disease can develop pulmonary vascular remodeling and PVD after months of PDA exposure, we found no echocardiographic evidence in preterm infants that prolonged PDA exposure increases the incidence of BPD-PVD during the neonatal hospitalization.

Impact: In our study, preterm infants (<28 weeks' gestation) with bronchopulmonary dysplasia (BPD) had a 15% incidence of pulmonary hypertension (PH) beyond 36 weeks' postmenstrual age as a comorbidity. Moderate/large patent ductus arteriosus (PDA) shunts increased the risk of flow-associated PH when present beyond 36 weeks. Although months of prolonged PDA exposure can cause pulmonary vascular remodeling and pulmonary vascular disease (PVD) in term infants with PDA-congenital heart disease, we found no echocardiographic evidence for an association between the duration of PDA exposure and the incidence of late PVD during the neonatal hospitalization in preterm infants with BPD.