[Pulmonary hypertension: a rare cause of unexplained dyspnea].

Pulmonary hypertension (PH) is defined by an increase in mean pulmonary artery pressure above 25 mmHg, measured at right heart catheterization. The various conditions (up to 37) leading to PH are described in a clinical classification identifying 5 groups, including pulmonary arterial hypertension (PAH). With an incidence of 2-4 cases/million/year, PAH is a rare, rapidly progressive and incurable form or PH. The differential diagnosis of PH relies on a decision tree, which is typically triggered by the presence of unexplained dyspnea and followed by a non invasive approach that includes simple tests such as EKG, chest radiography, pulmonary function tests and echocardiography. Other tests have some value to exclude chronic thromboembolic pulmonary hypertension, such as ventilation/perfusion scintigraphy, angio CT scanner and pulmonary angiogram. Finally, right heart catheterization is mandatory to establish the diagnosis of PH.