Abstract 11710: Sex Differences in Right Ventricular Flow Dynamics and Kinetic Energy in Healthy Volunteers

Introduction: Accurate right ventricular (RV) flow and function is crucial for optimal cardiovascular health. However, research on RV flow and function has lagged behind that for the left ventricle. Whole-heart 4D flow cardiovascular magnetic resonance (CMR) uniquely quantifies simultaneous multi-directional phasic blood flow and kinetic energy (KE). Gender differences in these parameters have not been well studied and may contribute to the predilection for developing certain cardiovascular diseases among females. This study aims to compare RV flow and KE parameters in healthy female and male subjects. Methods: Healthy subjects from 2 centers (n=163) were prospectively recruited to undergo 4D flow CMR. RV flow components —direct flow, retained inflow, delayed ejection flow and residual volume —and KE (KE=1/2·ρ blood · V voxel · v 2 where ρ blood is blood density 1.06 g/cm 3 ; V voxel , voxel volume; and v , velocity) were calculated. All KE parameters were indexed to RV end-diastolic volume (KEi EDV ) and expressed in μJ/ml. KEi EDV parameters at physiologically relevant epochs (global [entire cycle], systole, diastole) and cardiac cycle time points (peak systole, peak E-wave, peak A-wave) were extracted from a time-resolved KEi EDV curve. Results: Compared to males (n=95, mean age 44 years old), females (n=68, mean age 42 years old) had higher RV ejection fraction but smaller RV volumes; higher RV direct flow (38 vs 34%, P=0.007) and delayed ejection flow (17 vs 15%, P=0.043) and lower RV residual volume (27 vs 33%, P=0.001). Females had higher global KEi EDV (8.9 vs 7.5μJ/ml, P=0.005), diastolic KEi EDV (6.7 vs 5.6μJ/ml, P<0.001), peak E-wave KEi EDV (14.4 vs 11.9μJ/ml, P<0.001) and E-wave/A-wave ratio (1.68 vs 1.30, P=0.028) than males. No differences were observed for RV retained inflow, RV peak systolic, average systolic and peak A-wave KEi EDV between gender. Conclusion: Females have higher RV direct flow and lower RV residual volume, higher preload-adjusted RV global, average diastolic, peak E-wave and E-wave/A-wave ratio KEi EDV , compared to males by 4D flow cardiovascular magnetic resonance imaging. These parameters that related to right heart efficiency may lead to further understanding of the sex-based predispositions to right heart disease.