Late onset of pulmonary hypertension in very low birth weight infants.

Introduction: Pulmonary hypertension (PH) is a recognized complication of bronchopulmonary dysplasia (BPD). Recent guidelines recommend evaluating all infants with BPD for PH echocardiogram, but the specific timing of this screening is controversial. We aimed to identify the timing of PH diagnosis in a cohort of very low birthweight infants (VLBW) to determine appropriate age at screening.

Methods: We retrospectively reviewed data on 455 VLBW infants undergoing echocardiography at our institution. The timing of all echocardiograms, PH diagnosis on echocardiography, and BPD diagnosis at 36 weeks corrected age were extracted. PH was defined as dilation of the right sided chambers or RVH, flattening or leftward deviation of the septum, TR >25 mmHg, or 2/3 systemic pressures, or right to left shunting.

Results: Fifteen VLBW infants had PH identified on echocardiography, of whom 11 had BPD and 2 died before BPD status at 36 weeks could be ascertained. PH was most often identified on echocardiography after 36 weeks corrected age, and typically around 40 weeks. Ten of the infants ultimately diagnosed with PH had previous echocardiograms performed that were negative for PH at 25-46 weeks.

Conclusions: In our cohort of VLBW infants, onset of PH was typically found later than the 36-38 week range used by recently described screening programs. These findings suggest a need to examine echocardiograms obtained after 36 weeks for evidence of late-onset PH in vulnerable infants born at VLBW.