Pulmonary arterial hypertension is associated with the development of right heart failure. In the setting of heart failure, the heart shifts to increasing dependence on glucose metabolism. In this study, the investigators will perform cardiac positron emission tomography/magnetic resonance imaging (PET/MRI) scans to measure glucose metabolism in the heart before and after initiation of pulmonary vasodilator therapy for pulmonary arterial hypertension. By utilizing a rest-exercise protocol and continuous PET imaging acquisition, we can capture real-time changes in glucose uptake in the heart in response to acute exercise. By coupling these measures of dynamic glucose utilization with MRI-based cardiac function, we will determine cardiac metabolic efficiency.
