Computational Analysis of Wall Shear Stress Patterns on Calcified and Bicuspid Aortic Valves: Focus on Radial and Coaptation Patterns

Abstract

Calcification and bicuspid valve formation are important aortic valve disorders that disturb the hemodynamics and the valve function. The detailed analysis of aortic valve hemodynamics would lead to a better understanding of the disease’s etiology. We computationally modeled the aortic valve using simplified three-dimensional geometry and inlet velocity conditions obtained via echocardiography. We examined various calcification severities and bicuspid valve formation. Fluid-structure interaction (FSI) analyses were adapted using ANSYS Workbench to incorporate both flow dynamics and leaflet deformation accurately. Simulation results were validated by comparing leaflet movements in B-mode echo recordings. Results indicate that the biomechanical environment is significantly changed for calcified and bicuspid valves. High flow jet velocities are observed in the calcified valves which results in high transvalvular pressure difference (TPG). Wall shear stresses (WSS) increased with the calcification on both fibrosa (aorta side) and ventricularis (left ventricle side) surfaces of the leaflet. The WSS distribution is regular on the ventricularis, as the WSS values proportionally increase from the base to the tip of the leaflet. However, WSS patterns are spatially complex on the fibrosa side. Low WSS levels and spatially complex WSS patterns on the fibrosa side are considered as promoting factors for further calcification and valvular diseases.

Impact of Multi-Grade Localized Calcifications on Aortic Valve Dynamics under Helical Inflow: A Comparative Hemodynamic Study

“…The asymmetrical formation of calcification deposits on one or two leaflets leads to additional stress on the remaining non-calcified leaflets. Unlike previous studies [11,50,51] that focused on uniformly calcified leaflets, our findings indicate that localized calcification directs the flow towards the ascending aorta's wall, and the study by [52] suggests this redirection has the potential to cause harm to the wall. Some research suggests this redirection has the potential to cause harm to the wall [52].…”

Numerical simulation of coronary arteries blood flow: effects of the aortic valve and boundary conditions

“…𝑠𝑠] [14]. The motion of the aortic valve with flexible leaflets is governed by the linear momentum balance equation, considering a linear elastic and isotropic material, with the Young's modulus of 1[𝑀𝑀𝑃𝑃𝑃𝑃], Poisson's ratio of 0.45, and density 𝜌𝜌 𝑠𝑠 = 1000[𝑘𝑘𝑘𝑘/𝑚𝑚 3 ], in line with previous studies[15,16]. The equilibrium of surface forces is applied at the interface between the solid and fluid parts of the domain.…”

“…The mesh characteristics of the computational domain are summarized in Table 3. [15,16]. The equilibrium of surface forces is applied at the interface between the solid and fluid parts of the domain.…”

Effect of Intraluminal Thrombus Burden on the Risk of Abdominal Aortic Aneurysm Rupture

“…For the data transfer between the fluid and solid domains, a two-way iterative coupling method is employed. In two-way coupling, the flow-induced forces are transferred to the solid domain [ 45 ]. The materials in the solid domain deform under the effect of transferred fluid-induced forces, and therefore, the geometric form of the solid changes.…”