Numerical simulation of fluid-structure interaction analysis for the performance of leaflet reimplantation with different types of artificial graft

Background and objective: In clinical practice, valve-sparing aortic root replacement surgery primarily addresses left ventricular dysfunction in patients due to severe aortic regurgitation, but there is controversy regarding the choice of surgical technique. In order to investigate which type of valve-sparing aortic root replacement surgeries can achieve better blood flow conditions, this study examines the impact of changes in the geometric morphology of the aortic root on the hemodynamic environment through numerical simulation.

Methods: An idealized model of the aortic root was established based on data obtained from clinical measurements, including using the model of the aortic root without significant lesions as the control group (Model C), while using surgical models of leaflet reimplantation with tubular graft (Model T), leaflet reimplantation with Valsalva graft (Model V), and the Florida sleeve procedure (Model F) as the experimental groups. Fluid-structure interaction numerical simulations were conducted to assess the differences in blood flow between the three surgical techniques.

Results: Compared to the control group, all the three experimental groups showed no abnormal blood flow patterns in the aortic root. Additionally, the distribution of high-velocity blood flow was similar to that of the control group. Due to the changes in geometric shape after surgery, the impact locations of blood on the vessel wall varied, leading to different degrees of wall shear stress concentration at the sinus-conduit junction and the aortic valve ring in the three surgical models. During the peak systolic phase, the maximum opening area of the leaflets in the three surgical models (T, V, and F) differs from that of the control model, with the disparity in aortic valve leaflet opening area being 6.42 %, 9.17 %, and 8.63 %, respectively. When comparing the leaflet closure states, it was found that the closure velocity in Model V was close to that of Model C.

Conclusions: The changes in the geometry of the aortic sinus affect the hemodynamics within the aorta, and leaflet reimplantation with Valsalva graft and Florida sleeve procedures are more stable during blood flow impacts.