Management of pulmonary hypertension in infants with congenital diaphragmatic hernia.

In infants with congenital diaphragmatic hernia (CDH), a posterolateral diaphragmatic defect results in herniation of abdominal contents into the chest and compression of the intrathoracic structures. In the most severe cases, hypoplasia of the ipsilateral and contralateral lungs, severe pulmonary hypertension (PH) and left ventricular (LV) hypoplasia/dysfunction all contribute to increased mortality. The management of PH in CDH is complicated by structural and functional changes in the heart, pulmonary vasculature, airways and lung parenchyma; consequently, determining optimal management strategies is challenging. Treatment of PH in patients with CDH changes as the underlying pathophysiology evolves in the days and weeks after birth. During the early transition, the use of pulmonary vasodilators is limited by LV structural and functional abnormalities, and pulmonary vasodilators such as inhaled nitric oxide (iNO) may have a limited role (for example, stabilization for extracorporeal membrane oxygenation (ECMO), treatment of marked preductal desaturation and treatment of PH as LV performance improves). In contrast, subacute treatment of PH in CDH with iNO has an important role in recurrent or persistent PH and potentially improves survival. Chronic PH and vascular abnormalities may persist into childhood in patients with CDH, contributing to late mortality. It is unclear how pulmonary vasodilator therapies, such as iNO, sildenafil and bosentan, will modulate late outcomes in CDH with late/chronic PH.