Idiopathic pulmonary arterial hypertension (PAH) is a life-threatening disorder of uncertain cause that leads to progressive right heart failure and death. Average survival has improved from about 2.8 years in the early 1990s to approximately 5-7 years with current treatments, but most patients will still die of their disease. Two classes of oral medications are approved for use in PAH: endothelin-1 antagonists, and phosphodiesterase-5 inhibitors. Both improve walk distance and symptoms in PAH, but most patients still have continued dyspnea, fatigue and significant elevations in pulmonary pressures. Those who remain severely impaired are generally started on a continuous intravenous prostacyclin. For those who are less ill but still symptomatic, few options are available.