Impact of body position on hemodynamic measurements during exercise: A tale of two bikes

The addition of exercise testing during right heart catheterization (RHC) is often required to accurately diagnose causes of exercise intolerance like early pulmonary vascular disease, occult left heart disease, and preload insufficiency. We tested the influence of body position (supine vs. seated) on hemodynamic classification both at rest and during exercise. We enrolled patients with exercise intolerance due to dyspnea who were referred for exercise RHC at the Cleveland Clinic. Patients were randomized (1:1) to exercise in seated or supine position to a goal of 60 W followed by maximal exercise in the alternate position. We analyzed 17 patients aged 60.3 ± 10.9 years, including 13 females. At rest in the sitting position, patients had significantly lower right atrial pressure (RAP), mean pulmonary artery pressure (mPAP), pulmonary artery wedge pressure (PAWP) and cardiac index (CI). In every stage of exercise (20, 40, and 60 W), the RAP, mPAP, and PAWP were lower in the sitting position. Exercise in the sitting position allowed the identification of preload insufficiency in nine patients. Exercise in either position increased the identification of postcapillary pulmonary hypertension (PH). Body position significantly influences hemodynamics at rest and with exercise; however, mPAP/CO and PAWP/CO were not positionally affected. Hemodynamic measurements in the seated position allowed the detection of preload insufficiency, a condition that was predominantly identified as no PH during supine exercise.