Trial to Evaluate Parenteral Treprostinil and Riociguat on Right Ventriculo-vascular Coupling and Morphology in Those With Advanced PAH

This study is evaluating the combination of two medications — treprostinil (given through a vein or under the skin) and riociguat (a pill) — in patients with severe pulmonary arterial hypertension (PAH), a condition where blood pressure in the lungs is dangerously high. Researchers are looking at how this combination affects the right side of the heart and the blood vessels in the lungs. **You may be eligible if...** - You have been diagnosed with Group 1 pulmonary arterial hypertension (PAH) - Your lung blood pressure is high as confirmed by a right heart catheterization procedure - Your pulmonary hypertension specialist has determined you need parenteral (injected) treprostinil treatment **You may NOT be eligible if...** - Your blood pressure is critically low or you need medications to keep blood pressure up - You are expected to need a mechanical heart support device or a lung transplant within 3 months - Your left heart function is significantly weakened, or you have serious heart valve problems - You have severe lung disease Talk to your doctor to see if this trial is right for you.