Inhaled Nitric Oxide/INOpulse DS for Pulmonary Arterial Hypertension (PAH)

Study to determine if inhaled nitric oxide (iNO) given through a special delivery device (INOpulse® DS) is safe and efficacious in treating Pulmonary Arterial Hypertension (PAH). Medical literature and clinical experience suggests that iNO at pulsed doses of 0.013 to 0.1 mg/kg per hour for 1 month to 2+ years appears safe and suggests efficacy for the treatment of pulmonary hypertension. There are two parts to this study. In Part 1 (week 0 to week 16), the objectives are to determine the safety, tolerability, efficacy, and exploratory objectives of two different doses of iNO delivered by a pulsed delivery device in symptomatic subjects with PAH who remain symptomatic due to PAH on approved PAH monotherapy or combination approved PAH therapy. In Part 2 (week 17 to end of study Part 2 \[EOS Part 2\]), the objective is to compile data on the long-term effects of iNO on safety, tolerability, clinical and hemodynamic measures.