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.

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, with no noted ascending aortic dilation. The model’s sensitivity to graft properties and leaflet material heterogeneity was analyzed.

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, but were absent pre-surgery. Accounting for aortic valve leaflets in FSI studies yielded qualitatively similar results to the CFD cases, albeit with locally 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).

We demonstrated that the novel Hegar dilator-based STJ reconstruction restores normal blood flow patterns, highlighting the importance of reprofiling the aortic sinuses and STJ. 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. Competing Interest Statement The authors have declared no competing interest. Abbreviations - ATAA - Ascending Thoracic Aortic Aneurysm - BSA - Body Surface Area - CFD - Computational Fluid Dynamics - CTA - Computed Tomography Angiography - FEA - Finite Element Analysis - FSI - Fluid-Structure Interaction - GOA - Geometric Orifice Area - LCC - Left Coronary Cusp - LVOT - Left Ventricular Outflow Tract - NCC - Non-Coronary Cusp - OSI - Oscillatory Shear Index - RCC - Right Coronary Cusp - STJ - Sino-Tubular Junction - TAWSS - Time Average Wall Shear Stress