Phenotyping the right ventricle in pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a disease in which the lumen of small pulmonary arteries is narrowed because of vasoconstriction, hyperproliferation, inflammation and remodeling of smooth muscle cells and endothelial cells. This leads to an increase in resistance of the pulmonary vascular bed and an therefore an increase in pulmonary artery pressures. As a result the load on the right ventricle (RV) drastically increases, with a subsequent rise in RV wall stress. The RV will initially decrease this wall stress via increasing its wall thickness through hypertrophy and enhancing its contractility. Current PAH-medication decreases the pulmonary vascular resistance (PVR) and therefore reduce the RV afterload, but seldom normalizes it. As a result, the transition of RV adaptation towards RV failure, characterized by RV dilatation and decreased cardiac output, will be inevitable. To date, lung transplantation is the only cure for PAH-patients. To provide timely referral to a transplantation center, it is of utmost importance to identify ‘adapted’ PAH-patients who are prone to develop RV failure. To do so, key players in the transition from RV adaptation towards RV failure have to be identified. In this thesis, we aimed to further identify factors playing a role in RV adaptation and RV failure by comparing different phenotypes of PAH patients. Secondly, we evaluated the use of RV imaging during follow-up in PAH.