Definition

Persistent pulmonary hypertension of the newborn (PPHN) is a syndrome resulting from maladaptation to extrauterine life without a sustained normalization of pulmonary vascular resistance (PVR). PPHN is characterized by an elevation in PVR with resultant hypoxemia due to right-to-left shunting at the ductal and/or atrial level. PPHN may be confused with, or may coexist with, congenital heart disease: PPHN is frequently idiopathic but may be associated with respiratory failure/alveolar hypoxia (e.g., meconium aspiration syndrome, congenital pneumonia, sepsis, birth asphyxia, respiratory distress syndrome (RDS)), lung hypoplasia (e.g., congenital diaphragmatic hernia, alveolar capillary dysplasia) and maternal medication (e.g., late gestational use of selective serotonin reuptake inhibitors (SSRI); see Table 3.8).

Syndrome

Persistent fetal circulation (PFC) is used rarely.

Epidemiology

Incidence 0.67/1000 to 1.9/1000 live births. The risk of PPHN is about sixfold increased in newborns whose mothers used antidepressants of the SSRI class (e.g., Prozac®) after 20 weeks of gestation, with an overall incidence of approx. 6 to 12 per 1000 exposed women. However, the latter risk increase is based on a retrospective case controlled study with a very small effect size, i.e., 99% of women exposed to SSRI will have a baby not affected by PPHN. The incidence of “idiopathic” PPHN in neonates with Down syndrome (trisomy 21) is high (≈12/1000), but in the absence of associated conditions there is resolution of PPHN.

Etiology/pathophysiology

• See also p. 63 “Postnatal cardiopulmonary adaptation”

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