Pulmonary arterial hypertension (PAH) is characterized by a progressive increase of pulmonary vascular resistance eventually leading to right-heart failure. PAH includes idiopathic PAH and pulmonary hypertension associated with various conditions such as congenital systemic-to-pulmonary shunts. Prognosis to a large extent depends on the underlying etiology. Before the availability of targeted medical therapies, the median survival for patients with idiopathic PAH was 2.8 years. Patients with Eisenmenger syndrome have a more favorable prognosis (3-year survival rates > 75%). Treatment consists of pulmonary vasodilator therapy, long-term oxygen therapy, anticoagulation, and lung transplantation or, at times, heart-lung transplantation.- In recent years, percutaneous atrial septostomy has been established as palliative treatment or bridge to transplantation in patients with severe right-heart failure refractory to conventional therapy.