This observational study is being done to understand why people with scleroderma can develop pulmonary arterial hypertension (high blood pressure in the lungs, abbreviated PAH) and a weak heart muscle (heart failure). The study will also help the investigators understand why people with PAH from an unknown cause (called idiopathic PAH, or IPAH) can also develop a weakened heart muscle. The response of the right side of the heart or right ventricle (RV) to standard PAH therapy in scleroderma-associated PAH and in IPAH will be assessed. Blood and tissue samples will be collected from research participants during participants' normal standard of care procedures. People with scleroderma-associated PAH or idiopathic cause (IPAH) who need a right heart catheterization may join this study.