Pulmonary hypertension in congenital diaphragmatic hernia.

Clinically significant pulmonary hypertension (PHTN) is a common finding in newborn infants with congenital diaphragmatic hernia (CDH) resulting in right to left shunting at pre- and postductal level, hypoxemia, and acute right heart failure in those most severely affected. Even in those without clinical manifestations of ductal shunting, cardiac echo studies would suggest that increased pulmonary vascular resistance and right ventricular pressures are almost a universal finding in this disease, and in some instances, may persist well into the postnatal period. The lung is small and structurally abnormal, and the pulmonary vascular bed is not only reduced in size, but responds abnormally to vasodilators. During the last 20 years, "gentle" ventilation, delayed surgery, and improved peri-operative care have made the greatest impact in decreasing mortality in this condition. Use of PGE1 should be considered early if there is hemodynamically significant PHTN, right ventricular dysfunction, and the patent ductus arteriosus (PDA) is becoming restrictive. In individual patients, inhaled nitric oxide (iNO) might be helpful, but the response to iNO should be confirmed using echocardiography. In patients who survive operation and leave the hospital, there are chronic causes of morbidity that need to be looked for and managed in a multi-disciplinary follow-up clinic.