Cardiac Assessment by PV Loop in IPAH and Scleroderma PAH

Patients with scleroderma associated pulmonary hypertension (with or without interstitial lung disease) have a worse prognosis compared to patients with idiopathic pulmonary arterial hypertension (IPAH). The investigators have discovered through a previous protocol that patients with scleroderma associated pulmonary hypertension (SSc-PAH) have intrinsic right ventricular (RV) contractile dysfunction compared with patients with idiopathic pulmonary hypertension (IPAH) despite similar afterload imposed by the pulmonary vasculature. Patients with scleroderma or presumed/known IPAH who are clinically referred for right heart catheterization (RHC) will undergo, in addition to a clinically indicated RHC, state-of-the-art Pressure-Volume (P/V) Loop Assessment and RV biopsy for research purposes. The investigators will also do a standard pathologic assessment of the RV tissue (H\&E, special staining, electron microscopy), microvascular density measurements using immunohistochemistry techniques and isolated skinned myocyte experiments. Additional experiments will include proteomics, genomics/genetics, and RV protein and microRNA expression. The investigators will compare these findings in both groups (IPAH and SSc-PAH), before and after standard treatment for 6 months, in order to fully understand the differences in how the RV adapts to pressure overload and reasons for impaired RV function in SSc-PAH as well as identifying potential therapeutic targets.