Diagnosis and management of primary pulmonary hypertension.

Pulmonary arterial hypertension in children can occur secondary to shunt lesion like ventricular septal defect, patent ductus arteriosus or it may be idiopathic, the so-called primary pulmonary hypertension (PPH). The progression of PPH is usually rapid in children as compared to adults and the mean survival is 2-3 years after the diagnosis is made. Histological changes in the form of medical muscular hypertrophy, intinal hyperplasia and later angiornatous, plexiform lesions occur in pulmonary vasculature. The pulmonary vasculature normally is a high flow, low resistance circuit and allows large blood flow without marked increase in pulmonary arterial pressure. However, with prolonged increased flow or any other vasoconstrictor stimulus, histological changes start occurring in the pulmonary bed resulting in increasing pressure in pulmonary artery. Right ventricular hypertension follows resulting in right ventricular hypertrophy and later dysfunction. Life threatening arrhythmias may result in sudden death in some of these patients. Clinical presentation is in the form of exertional dyspnoea with syncope at times. Over 50% of children with PPH are helped by vasodilators. They may be treated with calcium channel blockers (e.g. nifedipine, dose titrated to blood pressure) orally. Those not responding to oral vasodilators can be put on chronic inhaled nitric oxide or continuous intravenous prostacyclin infusion. Chronic anticoagulation therapy may also increase survival. In symptomatic cases, blade/balloon atrial septostomy may increase survival in patients of PPH with intact atrial sptum. For children not responding to medical therapy, lung transplantation may be the answer in near future.