TABLE 1.

Pulmonary vascular phenotypes of prematurity

• Early (first 2 weeks of life)

1) PPHN Syndrome: hypoxemic respiratory failure with supra-systemic PAP causing extrapulmonary right-to-left shunting of blood across the patent foramen ovale and/or ductus arteriosus;

2) Delayed pulmonary vascular transition: variable patterns of changes in estimated PAP in the absence of severe hypoxemia due to PPHN physiology, associated with higher risk for BPD and mortality;

3) Early pulmonary hypertension at postnatal day 7: as a “biomarker” for BPD, late PH and prolonged respiratory disease in early childhood.

• Late (weeks to months after birth)

1) Associated with evolving or established BPD, especially in infants with severe BPD, clinically characterized by sustained need for respiratory support and supplemental oxygen therapy, often with recurrent cyanotic episodes if severe;

2) Pulmonary hypertension after NICU discharge with persistent or late respiratory morbidities, such as intermittent hypoxia, obstructive sleep apnea, acute viral infections, aspiration and other stresses.

• Chronic (months to years, or “pulmonary vascular disease across the lifespan”)

1) Persistent subclinical echocardiogram abnormalities during infancy and childhood

2) May contribute to exercise intolerance

3) “Borderline” or mild elevation of pulmonary artery pressure reflecting pulmonary hypertension, with or without abnormal cardiac structure and function in prematurely-born adults.