Pulmonary hypertensive diseases.

The commonest causes of pulmonary hypertension are secondary to endstage pulmonary disease or congenital heart disease (including structural abnormalities of the pulmonary veins). Less obvious causes include sleep disordered breathing due to obstructive sleep apnoea or neuromuscular disease, and occult interstitial lung disease. When these have been excluded, the primary pulmonary vascular diseases should be considered. These are primary pulmonary hypertension; pulmonary veno-occlusive disease; pulmonary embolic disease (thromboembolism, and non-thrombotic embolism) and invasive pulmonary capillary haemangiomatosis. The clinical signs and chest X-ray appearances are often non-specific. Echocardiography can often estimate pulmonary artery pressure and exclude congenital heart disease. Right heart catheterization is usually needed to confirm the diagnosis, estimate any reversibility of elevated pulmonary vascular resistance and exclude other causes. Precise diagnosis may require an open lung biopsy. For many of these conditions, treatment is difficult and the prognosis poor unless the child has a lung transplant.