“Cardiovascular disease is the world’s biggest killer, as well as the second biggest cause of death in the UK with over three million people suffering from atherosclerotic cardiovascular disease” (UK Government, 2020). Atherosclerosis, the narrowing of arteries due to a build-up of plaque, can be treated through medical interventions such as balloon angioplasty and stent implantation to dilate the stenosed vessel and to restore and maintain physiological blood flow. However, these procedures can result in adverse complications like stent thrombosis and in-stent restenosis. Factors such as stent morphology, stent spacing and stent implantation position alter the local haemodynamic environment, which is known to regulate stent thrombosis. The Lattice Boltzmann method is used to numerically model two-dimensional blood flow around a stent strut to explore how stent morphology affects the local haemodynamics. This method is a niche CFD approach with possible addition of mesoscopic physics, examination of real stent profiles and the coupling of an advection-diffusion equation to obtain relative residence time (RRT) values. Three different stent strut profiles (circular, square and trapezium) from the market are analysed in this work. As these struts had different strut heights, additional simulations that studied the same profiles but with equal strut height were required to highlight the effects of strut profile on local haemodynamics. Metrics of haemodynamics including wall shear stress (WSS), shear rate, RRT and re-circulation region length post strut were measured for each profile. These metrics were then used to assess the thrombogenicity of each stent strut design. The results showed that the circular profile was the least thrombotic profile, with the smallest: (i) max WSS, (ii) max shear rate, (iii) max RRT and (iv) re-circulation region post strut of the three struts. The trapezium shaped profile was the most thrombotic, with the largest of the previously mentioned metrics. Therefore, the simulation results from different stent profiles with equal strut height show that the more streamlined a stent strut is, the less likely stent thrombosis is to occur.

References

UK Government. (2020). UK Government tackles heart disease with new partnership [Press release]. Retrieved from https://www.gov.uk/government/news/uk-government-tackles-heart-disease-with-new-partnership#:~:text=Cardiovascular%20disease%20is%20the%20world%27s

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