Clevidipine for Vasoreactivity Evaluation of the Pulmonary Arterial Bed

CARVE is a Phase 4 open-label descriptive observational trial in PAH patients undergoing invasive vasoreactivity testing in the cath lab at the Dallas VA Medical Center. Patients clinically indicated for RHC and assessment of pulmonary artery vasoreactivity will be enrolled if they meet the inclusion/exclusion criteria. The study will involve the following tests: 1. Performance of clinically indicated RHC with assessment of pulmonary hypertension and pulmonary vascular resistance (PVR). 2. Performance of clinically indicated pulmonary vasoreactivity assessment with IV Nitroprusside (standard of care) 3. For patients who are responsive to Nitroprusside, or those who have an inconclusive result because of intolerability to Nitroprusside, pulmonary vasoreactivity assessment with study drug (IV) will be conducted.