Pulmonary arterial hypertension (PAH), characterized by increased pulmonary vascular resistance and arterial pressure,Pulmonary vasoconstriction and associated remodeling of the vascular walls are thought to be involved in the initiation of pulmonary arterial hypertension (PAH), a pulmonary vascular disease that, if left untreated, can lead to heart failure and death,Pulmonary arterial hypertension (PAH) has evolved from a disease with limited treatment options to one where numerous therapies that target three key pathophysiological pathways in the disease (i.e. the prostacyclin, endothelin and nitric oxide pathways) are available (Humbert M et al., (2014)) All three pathways can now be targeted with approved drugs that significantly improve long- term outcomes