Pilot Study Evaluating the Safety and Performance of the GeNO NITROsyl Delivery System for Inhaled Nitric Oxide

Inclusion Criteria: * Have a confirmed diagnosis of PAH, WHO Group 1. * WHO Functional Class II or III equivalent, PAH. * Have been clinically stable with regard to signs and symptoms of PAH for at least 30 days prior to RHC. * May be receiving approved mono therapies or combination PAH therapies. * Females that are surgically sterile or post-menopausal. Females of chil-bearing potential must have negative pregnancy test and must be practicing adequate birth control. Exclusion Criteria: * Have had a new type of chronic therapy (including but not limited to oxygen, a different category of vasodilator, a diuretic, digoxin) for PAH added within (1) month of RHC. * Have any PAH medication except for anticoagulants discontinued within the week prior to RHC. * Have evidence of significant parenchymal lung disease as evidenced by pulmonary function tests within the last six months * CREST (calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, telangiectasia) syndrome * Have a history of uncontrolled sleep apnea within three months of RHC. * Have a history of hemodynamically significant left-sided heart disease * Have evidence of left-sided heart disease * Have any other disease that is associated with pulmonary hypertension (e.g. congenital systemic-to-pulmonary shunt, sickle cell anemia, schistosomiasis). * Documented uncontrolled systemic hypertension as evidenced by systolic blood pressure greater than 160 mmHg or diastolic blood pressure greater than 100 mmHg. * Have used prescription appetite suppressants within 3 months prior to wean/transition. * Have chronic kidney disease stage IV or worse or the requirement for dialysis. * Be receiving an investigational drug, have in place an investigational device, or have participated in an investigational drug study within the past 30 days. * Have had an atrial septostomy. * Have anemia (hemoglobin \<10 g/dL), active infection or any other ongoing condition that would interfere with the interpretation of study assessments. * Have any serious or life-threatening disease other than conditions associated with PAH (e.g. malignancy requiring aggressive chemotherapy, renal dialysis, etc.). * Have unstable psychiatric status or be mentally incapable of understanding the objectives, nature or consequences of the trial * Participant is pregnant or lactating * Significant, ongoing alcohol or drug abuse.