We hypothesize that non-invasive indices of right ventricular RV (echocardiograph-derived strain and strain rate) and pulmonary (gas exchange-derived lung diffusion and surface area) function during light exercise will successfully identify and discern patients with known RV dysfunction pulmonary arterial hypertension and heart failure with preserved ejection fraction(PAH/HFpEF with RV failure) from those with known pulmonary dysfunction (PAH/HFpEF with pulmonary fibrosis). Additionally, we hypothesize that our assessment techniques will identify subtle derangements in RV and pulmonary function in newly diagnosed PAH and HFpEF patients, and that this may guide early and targeted therapeutic intervention.

We hypothesize that breathing hyperoxia will increase exercise capacity by reversing RV and pulmonary derangements, and that the mechanisms of action will be related to the underlying dysfunction (e.g., reducing pulse volume recording PVR, increasing RV functional reserve, increasing gas diffusion).

We hypothesize that non-invasive indices of RV (echocardiograph-derived strain and strain rate) and pulmonary (gas exchange-derived lung diffusion and surface area) function during light exercise will successfully identify and discern patients with known RV dysfunction (PAH/HFpEF with RV failure) from those with known pulmonary dysfunction (PAH/HFpEF with pulmonary fibrosis). Additionally, we hypothesize that our assessment techniques will identify subtle derangements in RV and pulmonary function in newly diagnosed PAH and HFpEF patients, and that this may guide early and targeted therapeutic intervention.

Stroke volume will be measured with echocardiography at rest and during exercise while breathing room air and hyperoxia

Oxygen uptake will be measured via pulmonary gas exchange at rest and during exercise while breathing room air and hyperoxia

Ventilatory effciency will be measured via pulmonary gas exchange at rest and during exercise while breathing room air and hyperoxia