[Pulmonary hypertension from the viewpoint of the pediatric pulmonologist]

The main cause of secondary pulmonary hypertension in the view of a pulmonologist is alveolar hypoventilation - eventually potentiated by acidosis and hypercapnia - which leads to reflectory hypoxemic vasoconstriction of the small pulmonary arteries. Anatomic changes in the pulmonary vessels may be absent or may be limited to medial hypertrophy of the arterioles. If the underlying cause of the hypoxia can be corrected, this reflectory pulmonary hypertension is reversible. In diffuse progressive lung disease, interstitial fibrosis with destruction of the alveolar wall and capillaries may occur, leading to restriction of the pulmonary vascular bed. In such cases pulmonary hypertension may not be completely reversible. The most frequent causes of pulmonary hypertension in childhood are obstructive (e.g. Cystic Fibrosis) or restrictive lung diseases (e.g. interstitial fibrosis). Rare but important in the differential diagnosis are upper airway obstruction, thoracic cage deformity, neuromuscular disorders, high altitude and respiratory center dysfunction. The therapy is elimination of the underlying disease or optimal treatment. In addition prophylactic or therapeutic longterm application of oxygen is more efficient than treatment with pulmonary vasodilators or modern substances like Almitrine. Right heart decompensation should be treated by diuretics. The longterm prognosis is dependent of the underlying disease and is poor in a chronic progressive lung disease like cystic fibrosis and certain types of lung fibrosis.