The Enduring Impact of Shape Following Perfect Coarctation of the Aorta Repair.

Objectives: Aortic arch appearances can be associated with worse cardiac function and chronic hypertension late after coarctation of the aorta (CoA) repair, even without residual obstruction. Statistical shape modeling (SSM) has identified specific 3D arch shapes linked to poorer cardiovascular outcomes. We sought a mechanistic explanation. Methods: From 53 asymptomatic patients late after CoA repair with no residual obstruction (age: 22.3 ± 5.6 years; 12-38 years after operation), eight aortic arch shapes associated with the four best and four worst cardiovascular parameters were obtained from 3D SSM. Four favorable shapes were affiliated with left ventricular (LV) ejection fraction +2 standard deviation (SD) values from the mean, and indexed LV end diastolic volume/indexed LV mass/resting systolic blood pressure that were -2SD. Four unfavorable shapes were defined by the reverse. Computational Fluid Dynamics modeling was carried out to assess differences in pressure gradient across the aortic arch and viscous energy loss (VEL) between favorable and unfavorable aortic arches. Results: In all aortic arches, the pressure gradients were clinically insignificant (<8 mm Hg). However, in the four unfavorable aortic arches, VEL were uniformly higher than those in the favorable shapes (VEL difference: 15%-32%). There was increased turbulence and more complex propagation of VEL along with the unfavorable aortic arches. Conclusions: This study reveals the variable flow dynamics that underpin the association of aortic arch shapes with worse cardiovascular outcomes late after successful CoA repair. Higher VEL persists in the unfavorable aortic arch shapes. Further understanding of the mechanism of viscous energy loss in cardiovascular maladaptation may afford mitigating strategies to monitor and modify this unrelenting liability.