age ≥18 and ≤ 80 years

ability to understand the research protocol and willing to sign the study informed consent

diagnosis of pulmonary arterial hypertension belonging to Class I and IV

stable haemodynamic status and optimized medical treatment since at least 2 months

ability to perform maximal cardiopulmonary exercise test and pulmonary diffusing capacity for carbon monoxide evaluation

Dead Space Evaluation in Pulmonary Hypertension