Right heart catheterization (RHC)-determined pulmonary hemodynamics are mandatory for the diagnosis and classification of pulmonary hypertension (PH) and can be used to assess response to PH-specific therapy and inform clinical decision-making. PH is diagnosed in patients with a mean pulmonary arterial pressure of ≥25 mm Hg at rest, with a further classification of pulmonary arterial hypertension (PAH) in patients with a pulmonary artery wedge pressure of ≤15 mm Hg and, often, reduced cardiac output. In addition, a number of hemodynamic variables, either measured directly with RHC or subsequently derived, have been shown to have prognostic significance in PAH, with different variables having more prognostic significance in specific patient populations. Although there is no hemodynamic definition of exercise-induced PAH, measurement of certain hemodynamic variables during exercise may identify an intermediary phenotype between healthy individuals and overt PAH at rest and may have prognostic implications. However, although exercise hemodynamics may be a closer reflection of the true resistive component of the pulmonary vasculature and its ability to respond to therapy, the lack of standardized protocols limits application in routine clinical practice.
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