FIGURE 2.

Schematic demonstration of changes in organ-level RV function at different stages of PAH. The RV initially responds to increased mean PA pressures (mPAP) via hypertrophy and increased RV wall thickness, which results in increased organ-level contractility (E_es) and maintained cardiac output, ejection fraction, and RV-PA coupling (adaptation). Later in the process, RV hypertrophy reaches a plateau while mPAP is further elevated. The RV then undergoes dilation to maintain cardiac output which, together with other multi-scale remodeling events at the tissue, fiber and myocyte-level, leads to depressed organ-level contractility (E_es), cardiac output, and ejection fraction. Sustained elevation in mPAP and decreased E_es results in reduced RV-PA coupling efficiency and RV-PA uncoupling (maladaptation). RV: Right ventricle; PAH: Pulmonary arterial hypertension; mPAP: Mean pulmonary artery pressures; PA: Pulmonary artery.