Abstract 15688: Computational Fluid Dynamics Assessment of Exercise in Patients With Successfully Repaired Coarctation of the Aorta

Abstract

Introduction: Patients with coarctation of the aorta (CoA) have decreased exercise capacity even after successful repair with no anatomic obstruction. Our previous work demonstrated a robust negative correlation of aorta size mismatch, defined by ascending (AAo) to descending aorta (DAo) diameter ratio (D AAo /D DAo ), and exercise capacity (VO2 max), suggesting geometry alters arch resistance. This study aims to identify the hemodynamic impact of aorta size mismatch with simulations of rest and exercise using computational fluid dynamics (CFD). Methods: An IRB-approved retrospective chart review identified patients with CoA repair who had a cardiac MRI and exercise stress test within 6 months. Each aorta was segmented and scaled to a body surface area of 1 m 2 . CFD was used to simulate rest (3 L/min/m 2 ) and exercise (9 L/min/m 2 ). Outlet resistance was tuned to match patient-specific DAo flow split derived from in vivo MRI and assumed unchanged for exercise. Power loss was calculated between AAo and DAo and correlated with D AAo /D DAo . Results: The patients (ages 12-41 years, mean 26.8±8.6), had a VO2 max ranging from 47 to 126% predicted (mean 92±20%). Power loss had a significant negative correlation with D AAo /D DAo at rest (p=0.001) and exercise (p<0.01). The ratio of power loss in exercise to rest positively correlated with D AAo /D DAo (p<0.05) (Figure). Conclusions: The relationship of power loss with aorta size mismatch is largely driven by altered flow distribution dependent on AAo and DAo size. There is a disproportionate increase in power loss with exercise compared to rest with a larger aorta size mismatch. This suggests arch geometry independently impacts power loss in exercise which is captured by the measurement of aorta size mismatch and can be a target for optimizing aortic arch repair. Figure: Ratio of power loss in exercise to rest correlates with D AAo /D DAo . Example aortic arches are shown with low power loss (green) and high power loss (red) with corresponding VO2.