Non-Invasive Measurement of Cardiac Output and Stroke Volume in PAH/CTEPH

Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are severe clinical conditions that, despite advances in therapeutics over the past 20 years, lead to serious morbidity and mortality. Guidelines on the diagnosis and treatment of pulmonary hypertension (PH) recommend the use of a multiparametric risk stratification tool to determine severity of disease, which should guide initial therapy and therapy modulation. This multiparametric risk stratification schema includes objective assessment of exercise capacity, right ventricular function and hemodynamic parameters in order to classify patients into severity categories. Cardiac index (CI) and right atrial pressure (RAP), measured via right heart catheterization (RHC), are the hemodynamic parameters used in risk assessment of PH. Arguably, stroke volume index (SVI) is the most important hemodynamic parameter for assessment of PH severity and there is currently no validated method for noninvasive measurement of cardiac output (CO), CI or SVI. Currently, a major obstacle in the field is that hemodynamic measurements are not obtained on a regular basis in the risk assessment and therapy modulation of patients with PAH and CTEPH. If a noninvasive method of hemodynamic measurement could be correlated with other objective measurements of risk assessment, it could become an invaluable tool in therapy initiation and modulation in the ambulatory setting. This is a single center study to evaluate the use of non-invasive measurement of CO and stroke volume to assess risk and response to treatment in patients with PAH and non- operable CTEPH. We anticipate to enroll a total of 100 subjects at Ronald Reagan UCLA Medical Center. A maximum of 10 hour in total for the study including the consent process, pre-procedure care, RHC procedure, and follow up visit. The initial visit will be approximately 4 hours with the RHC procedure itself will only be 20 minutes. Each follow up visit will be