Editorial Comment: Losartan and nifedipine therapy in patients with secondarypulmonary hypertension

Pulmonary arterial hypertension (PAH) is a debilitating chronic disease of the small pulmonary arteries that is charac- terized by vasoconstriction and vascular remodeling (1). Endothelial dysfunction is believed to occur early on in disease pathogenesis, leading to endothelial and smooth muscle cell proliferation and structural changes or remodeling of the pulmo- nary vascular bed resulting in an increase in pulmonary vascu- lar resistance. PAH is either idiopathic or occurs in association with various conditions such as connective tissue diseases, HIV infection, portal hypertension, chronic hypoxic pulmonary dis- ease, left heart disease, and left-to-right congenital shunts. Although some pathophysiological properties of PAH related to these diseases are similar especially in the terminal phase, mechanisms of increase in pulmonary arterial pressure (PAP) and thereby appropriate treatment are different according to etiology, especially in early phase of the diseases.