Relatively few works deal with the analysis of hemodynamics in patient-specific models when an endovascular device, e.g., a stent, is present. This shortfall is largely due to two main difficulties: i) the stent geometry is often blurred in medical images; ii) the creation of analysis-suitable meshes able to catch the protrusion of the slender stent struts into the blood volume is highly time-consuming and challenging.
As part of his PhD, Giovanni Maria Formato has set up a framework to easily and fast include the endovascular device into the blood domain. The framework consists of:
- A semi-automated local mesh refinement to improve the accuracy of the solution near the immersed stent;
- An immersed approach to compute the hemodynamics resulting from the presence of the stent inside the blood flow. This approach allows to take into account the presence of the stent by implicitly modifying the flow equations in the blood volume occupied by the immersed device, thus avoiding the cumbersome process of building a body-fitted mesh.
Fig. 1: The proposed meshing algorithm allows to easily obtain refined meshes near the immersed stent and vascular walls to achieve a good local accuracy of the solution. The method takes in input the .STL files of the vessel and the stent plus the desired mesh topological parameters.
Fig. 2: The immersed approach is used to compute the velocity and pressure fields in the computational domain. The method is able to capture the flow disturbances induced by the thin stent struts (watch the video below).
The framework will be used to easily simulate the hemodynamics resulting from different stent designs and implants, supporting the endovascular surgeons in the preoperative phase.
In this project, we exploited the open-source meshing libraries provided by GMSH and the multiphysics commercial code Ansys CFX, which are used by CompMech Group under an Academic License. Therefore, we would like to thank both GMSH and Ansys for providing the necessary tools to set up this framework.
March 27th, 2020