Biomechanical and Hemodynamic Measures of Right Ventricular Diastolic Function: Translating Tissue Biomechanics to Clinical Relevance

BACKGROUND: Right ventricular (RV) diastolic function has been associated with outcomes for patients with pulmonary hypertension; however, the relationship between biomechanics and hemodynamics in the right ventricle has not been studied. METHODS AND RESULTS: Rat models of RV pressure overload were obtained via pulmonary artery banding (PAB; control, n=7; PAB, n=5). At 3 weeks after banding, RV hemodynamics were measured using a conductance catheter. Biaxial mechanical properties of the RV free wall myocardium were obtained to extrapolate longitudinal and circumferential elastic modulus in low and high strain regions (E(1) and E(2), respectively). Hemodynamic analysis revealed significantly increased end‐diastolic elastance (E(ed)) in PAB (control: 55.1 mm Hg/mL [interquartile range: 44.7–85.4 mm Hg/mL]; PAB: 146.6 mm Hg/mL [interquartile range: 105.8–155.0 mm Hg/mL]; P=0.010). Longitudinal E(1) was increased in PAB (control: 7.2 kPa [interquartile range: 6.7–18.1 kPa]; PAB: 34.2 kPa [interquartile range: 18.1–44.6 kPa]; P=0.018), whereas there were no significant changes in longitudinal E(2) or circumferential E(1) and E(2). Last, wall stress was calculated from hemodynamic data by modeling the right ventricle as a sphere: [Formula: see text]. CONCLUSIONS: RV pressure overload in PAB rats resulted in an increase in diastolic myocardial stiffness reflected both hemodynamically, by an increase in E(ed), and biomechanically, by an increase in longitudinal E(1). Modest increases in tissue biomechanical stiffness are associated with large increases in E(ed). Hemodynamic measurements of RV diastolic function can be used to predict biomechanical changes in the myocardium.