Hemodynamic Analysis of a Repaired Ascending Aorta with Preserved Aortic Root

Purpose To evaluate the hemodynamic impact of restoring a normal sino-tubular junction (STJ) following a novel Hegar dilator-based procedure in patients undergoing root-sparing ascending thoracic aortic aneurysm (ATAA) repair using computational modeling. Methods We retrospectively selected an ATAA patient who underwent pre- and postoperative gated computed tomography angiography (CTA). We developed a novel workflow to segment the lumen, thick-walled aorta, and aortic valve from CTA images for subsequent blood flow analysis using computational fluid dynamics (CFD) and fluid-structure interaction (FSI). Morphological and hemodynamic characteristics of the root were quantified and compared against those of a control subject. Sensitivity analyses were performed to evaluate the impact of graft properties, leaflet material parameters and heterogeneity, wall compliance, external tissue support, and solid domain annular boundary conditions. Results Both CFD and FSI results showed that the postoperative geometry reconstructed with a normal STJ profile reintroduces sinus vortices during peak systole, similar to the control subject, which were absent pre-surgery. Accounting for aortic valve leaflets in FSI studies yielded a similar spatial patterning of the high-velocity jet and wall shear stress compared to the CFD data. However, FSI resulted in substantially elevated velocities, time-averaged wall shear stress (TAWSS), and energy dissipation, likely due to the dynamically changing orifice area and differing profiles of the left ventricular outflow tract (LVOT). Conclusion We demonstrated that restoring a normal sinus shape and STJ profile during ascending aortic repair may have potential hemodynamic benefits. The study also highlights the model's sensitivities, particularly the LVOT shape and leaflet morphology and mobility, and may assist planning STJ reconstruction to yield optimal hemodynamics before intervention.