Key result
A helical coronary stent design demonstrated a hemodynamic benefit in reducing thrombosis potential compared to closed-cell (-50.2%) and open-cell (-38.5%) designs based on wall shear stress.
Why the study?
Thrombus formation is linked to pathologically altered blood flow, necessitating consistent fluid-mechanical analysis of coronary stent designs.
Does a helical stent design improve time average wall shear stress distribution compared to closed-cell and open-cell designs in a vascular model?
Does a helical stent design improve time average wall shear stress distribution compared to closed-cell and open-cell designs in a vascular model?
Validated computational fluid dynamics demonstrate that a helical coronary stent design provides a hemodynamic benefit by reducing areas of low wall shear stress, potentially lowering thrombosis risk.
Answers are grounded in this paper and cite their sources.
Helical stent designs may reduce thrombosis potential in models; hypothesis-generating and should not yet change practice.
The formation of a thrombus is associated with dramatic consequences for the patient, such as increased risks of neurologic events and myocardial infarction or even death. A pathologically altered blood flow is associated with these complications. Consequently, a consistent fluid-mechanical analysis of implants, such as coronary stents, must be carried out. Computational fluid dynamics (CFD) is an important in silico tool for the analysis of different stent designs. Using three different generic stent designs (closed-cell, open-cell and helical), CFD could be performed with the OpenFOAM software package. The stents were implemented in a vascular model having a fully developed Hagen-Poiseuille velocity profile (u mean = 0.6 m/s) as inlet condition. In combination with the dynamic viscosity of the Newtonian test fluid of 6.04·10 -5 m 2 /s, Reynolds numbers up to 460 were achieved. Spatially high-resolved velocity fields from measurements in the magnetic resonance tomograph (magnetic resonance velocimetry, MRV) were available for validation. The velocity field was compared in selected cross sections and longitudinal sections. The difference of the main flow proximal and distal to the stent models were below 6 %. In addition, a similar flow topology could be quantified using the Q-criterion. Due to the very good agreement of the numerical results with the MRV-measurements, the numerical method has been applied to further analysis of stent designs regarding to time average wall shear stress (TAWSS) distribution on the luminal vessel surface (surface area with TAWSS < 0.4 Pa was related to overall vessel surface) under pulsatile conditions. Although all stent designs have the same square cross-section, a large influence of the stent design on WSS distribution could be observed (closedcell vs. helical = -50.2 %; open-cell vs. helical = -38.5 %). By using validated CFD it was possible to quantify the hemodynamic benefit of helical stent design in terms of thrombosis potential.
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Oldenburg et al. (2019) studied Coronary stent thrombosis. Helical stent design vs. Closed-cell and open-cell stent designs was evaluated on Time average wall shear stress (TAWSS) distribution (surface area with TAWSS < 0.4 Pa). A helical coronary stent design demonstrated a hemodynamic benefit in reducing thrombosis potential compared to closed-cell (-50.2%) and open-cell (-38.5%) designs based on wall shear stress.
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