Local hemodynamic analysis after coronary stent implantation based on Euler-Lagrange method

Abstract

Coronary stents are deployed to treat the coronary artery disease (CAD) by reopening stenotic regions in arteries to restore blood flow, but the risk of the in-stent restenosis (ISR) is high after stent implantation. One of the reasons is that stent implantation induces changes in local hemodynamic environment, so it is of vital importance to study the blood flow in stented arteries. Based on regarding the red blood cell (RBC) as a rigid solid particle and regarding the blood (including RBCs and plasma) as particle suspensions, a non-Newtonian particle suspensions model is proposed to simulate the realistic blood flow in this work. It considers the blood's flow pattern and non-Newtonian characteristic, the blood cell-cell interactions, and the additional effects owing to the bi-concave shape and rotation of the RBC. Then, it is compared with other four common hemodynamic models (Newtonian single-phase flow model, Newtonian Eulerian two-phase flow model, non-Newtonian single-phase flow model, non-Newtonian Eulerian two-phase flow model), and the comparison results indicate that the models with the non-Newtonian characteristic are more suitable to describe the realistic blood flow. Afterwards, based on the non-Newtonian particle suspensions model, the local hemodynamic environment in stented arteries is investigated. The result shows that the stent strut protrusion into the flow stream would be likely to produce the flow stagnation zone. And the stent implantation can make the pressure gradient distribution uneven. Besides, the wall shear stress (WSS) of the region adjacent to every stent strut is lower than 0.5 Pa, and along the flow direction, the low-WSS zone near the strut behind is larger than that near the front strut. What's more, in the regions near the struts in the proximal of the stent, the RBC particle stagnation zone is easy to be formed, and the erosion and deposition of RBCs are prone to occur. These hemodynamic analyses illustrate that the risk of ISR is high in the regions adjacent to the struts in the proximal and the distal ends of the stent when compared with struts in other positions of the stent. So the research can provide a suggestion on the stent design, which indicates that the strut structure in these positions of a stent should be optimized further.

Red blood cells tracking and cell-free layer formation in a microchannel with hyperbolic contraction: A CFD model validation

“…For vessels with diameters larger than the size of red blood cells, the assumption of rigid particles does not significantly affect the flow behavior of the blood mixture [24] . Simulation of rigid erythrocytes has as well been used to model two-phase blood flow in a vessel after a stent procedure [41] . Studies of rigidized red blood cells are also available in the literature to focus on the effects of rotational motions [42] .…”

Volumetric mass density measurements of mesenchymal stem cells in suspension using a density meter

“…They allow the investigation of mechanical strain and mechanical forces and can predict the trajectory of individual cells in cell suspensions using particle models based on the Euler-Lagrange approach. 6 , 7 , 8 These models also require the volumetric mass density of the cells as an input parameter. Lastly, Grover et al.…”

Risk factors for in-stent restenosis after coronary stent implantation in patients with coronary artery disease: A retrospective observational study

“…[ 5 ] ISR is one of the common complications after PCI and has been studied from the aspects of drug and stent type and implantation skills. [ 6 , 7 ] However, with the rapid development of PCI and the wide application of intravascular ultrasound, the indications for PCI are expanding with a concurrent increase in ISR incidence. Moreover, the mechanism of ISR remains unclear, with many factors reportedly being involved in its occurrence and development.…”