A Hidden Malice: Viscous Energy Loss Is Linked To Poor Late Outcomes Following A Hemodynamically Successful Aortic Coarctation Repair
Liam Swanson, MS1, Emilie Sauvage, PhD1, Malebogo Ngoepe, PhD2, Jan Bruse, PhD3, Silvia Schievano, PhD1, Tain-Yen Hsia, MD4.
1University College London, London, United Kingdom, 2University of Cape Town, London, United Kingdom, 3Vicomtech Foundation, Donostia-San Sebastian, Spain, 4Arnold Palmer Hospital for Children, Orlando, FL, USA.
Objectives: Specific aortic arch shapes are linked to poorer cardiovascular outcomes late after ‘successful' aortic coarctation (CoA) repairs without residual obstruction. We sought a mechanistic explanation.Methods: MR imaging of 53 asymptomatic patients late after CoA repair with no residual obstruction (22.3 ±5.6 years; 12-38 years post repair) were obtained to assess left ventricular ejection fraction (LVEF), indexed left ventricular end diastolic volume (LVEDVi), indexed left ventricular mass (LVMi), and resting systolic blood pressure (SBP). For each of the 4 outcomes, 3D arch shapes associated with best and worst values were obtained from Statistical Shape Modeling. 8 arch shapes were revealed. 4 best-performing shapes were identified by: 1)LVEF, +2 standard deviation (SD) from the mean, and by 2)LVEDVi, 3)LVMi, and 4)SBP that were -2SD from the mean. 4 worst-performing shapes were the reverse. Computational Fluid Dynamics modeling was carried out to assess pressure gradients and viscous energy losses (ELv).Results: Pressure gradients were clinically insignificant (<8 mmHg) in all 8 arch shapes. However, in the 4 worst-performing arch shapes, ELv were uniformly higher than in the best-performing shapes (ELv difference: 15-32%), with increased turbulence and more complex ELv propagation.Conclusions: Higher viscous energy loss in certain aortic arch shapes, following successful coarctation repair, is linked to poor cardiovascular outcomes. Medical and surgical strategies are needed to mitigate this insidious but unrelenting liability.
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