[Physiological functional tests to evaluate pulmonary arterial hypertension]

Pulmonary arterial hypertension (PAH) is a rare and complex disease, which requires careful diagnostic evaluation.

Most patients have a mild decrease in lung volumes and a moderate decrease in carbon monoxide transfer factor. Mild to moderate arterial hypoxaemia, is often present, associated with a mild respiratory alkalosis. When hypoxaemia is severe, it may represent an intracardiac shunt. Right heart catheterisation is required to confirm the diagnosis and in most cases shows a significant elevation of pulmonary artery pressure due to an increase in pulmonary vascular resistance. The haemodynamic profile and the response to an acute pulmonary vasodilator challenge are determinants of prognosis. Finally, exercise capacity which is usually assessed by the six minute walk test provides an overall functional measure of disease severity, response to therapy, and progression.

Functional evaluation of the heart using echocardiography will play an increasing role in the evaluation of PAH.

Physiological measurements in PAH have several objectives. They form part of the diagnostic definition, allow the exclusion of other conditions and are tools for the assessment of severity, prognosis and response to therapy.