Ricerc@Sapienza

Pulmonary arterial hypertension (PAH) is a clinical condition characterized by the presence of pre-capillary PH and pulmonary vascular resistance >3 Wood units, in the absence of other causes of pre-capillary PH. PAH prognosis is still poor with a median survival of 7 years. As a rare disease the European Union encourages research and gives priority founding on this field. Our Center is currently one of the most important Italian centers for PAH; it's the Reference Center for rare disease (idiopathic PAH) in the Lazio Region. Hypoxaemia is a frequent finding in patients with PAH and could be related to ventilation-perfusion mismatch, reduced diffusing capacity, decreased cardiac output or the opening of intrapulmonary (IP) or intracardiac shunt. Hypoxemia in PAH is one of the main determinants of exercise tolerance and prognosis. Desaturation during 6MWT is associated with a 2.9 relative mortality risk of in PAH. The most relevant and international registries consider more than 70% of all patients with PAH at the intermediate risk with an heterogenetic treatment response and a significant different mortality rate. Hypoxemia related to IP shunt is not included in the major PH international registries, mainly because of its complicated assessment. We want to conduct an observational and prospective study enrolling 50 consecutive PAH patients and following them for 12 months. A right heart catheterization will be performed at baseline and while breathing 100% oxygen for at least 10-15 minutes to calculate shunt fraction with the formula (Cc - Ca)/(Cc - Cv). A physician of our Center will perform follow-up visits every 3-6 months in order to detect an early clinical worsening. The inclusion of IP shunt in the risk scores may allow clinicians to better stratify patients at intermediate risk and to identify patients who need an earlier aggressive strategies such as lung transplantation.