The purpose of the study is to evaluate a technique to monitor disease progression or regression in patients with pulmonary arterial hypertension (PAH). PAH is indicated by high blood pressure in the pulmonary arteries. Right heart catheterization is currently the standard diagnostic test for PAH patients, but it requires sending a catheter inside the heart to measure pressure inside the heart chambers. This study will evaluate the feasibility of a test based on ultrasound that avoids sending a catheter inside the heart. Using echocardiography, which uses ultrasound, researchers will measure the energy state of the right ventricle to assess its function and monitor disease progression or regression. Participants in the study either have pulmonary hypertension type 1 with normal right ventricle (RV) function, or pulmonary hypertension type 1 with RV dysfunction. Healthy individuals (for comparison) may also participate.