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Item type:Publication, Access status: with files , Experimental corrosion and computational hemodynamic assessment of a 3D-printed biodegradable stent designCoronary artery disease (CAD) is a leading cardiovascular disorder caused by stenosis or occlusion of the coronary arteries. Stenting and bypass surgery are common treatment methods; however, conventional metal stents are prone to re-occlusion over time due to their permanent residence in the body. As a result, researchers have shown growing interest in biodegradable polymer stents. In this study, a novel stent and insert were 3D-printed with FDM and SLA using biocompatible PLA filament/resin. To assess corrosion resistance, the specimens were immersed in a simulated body fluid (SBF), and three corrosion tests were performed. Then, using field emission scanning electron (FESEM) images and 3D scanning, dimensional changes in the samples were extracted. The observations showed that in some places, the thickness of the samples increased by 0.1 mm compared to the original sample. Therefore, three samples with thickness increases of 0.1, 0.2, and 0.3 mm were designed and flow simulations were subsequently carried out. In simulations, the carreau viscosity model and pulsatile inlet flow were used. It was found that with increasing stent thickness, the insert becomes progressively less effective at increasing wall shear stress, leading to a higher probability of restenosis.Publicationtype: Journal Article6 8 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , A novel vascular stent and insert concept to improve hemodynamics and support vascular healthObstruction of vessels is one of the most common health issues in the world and various methods of treatments have been offered, including medication therapy, stenting, and bypass surgery. However, recurrence of blockage is a major issue facing patients. The present work assesses the performance of a new innovative design of stents featuring two spirals, called ‘inserts’, which will create a rotating flow inside the vessel. Three different cases of artery and bypass configurations were studied and the results showed that the stent and inserts increased the axial and secondary velocity significantly. At a plane located 1 mm after anastomosis and at t = 0.25 s, the axial velocity was 23% higher for a case with stent and insert compared to the baseline configuration i.e., without stent/insert. In addition, it was found that the presence of the insert increases the wall shear stress (WSS). The maximum WSS among the three cases reached 113 Pa, which was 94% higher than the baseline case. The findings highlight the potential of the proposed stent/insert design in improving the hemodynamic parameters in the graft, anastomosis region, and the host artery, which in turn, could enhance the patency and longevity of the bypass graft.Publicationtype: Journal Article10 12 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Effect of stent struts angle on body vessel shear stress at different heat fluxesToday, there are many methods for treating coronary artery blockage. Doctors determine the type of treatment according to many parameters, such as the patient's age and the degree of arterial blockage. A method of arteriosclerosis treatment is stenting. The body's activity in different conditions causes different thermal heat fluxes on the artery. This study was to obtain the optimum angle of the stent struts to get the suitable wall shear stress at different thermal heat fluxes of 5, 10, and 15 W m−2, which were applied in two conditions on the artery and stent; the first, the heat flux was applied on entire geometry of the artery and the stent, the second, the heat flux was applied only on the stent. For simulation, the finite volume method (FVM) and simple schemes were employed; furthermore, the Carreau viscosity model was selected for the non-Newtonian viscosity model. In addition, PLA stent material was considered in this study. The best optimum angle for stent struts was 61 degrees. It was also observed that the heat flux does not affect wall shear stress, axial and radial blood velocity profiles, and blood temperature on the artery centerline.Publicationtype: Journal Article13