EUROPEAN CONFERENCE ON SCIENCE, ART & CULTURE, Antalya, Turkey, 19 - 22 April 2018, pp.105
Vascular diseases such as cardiovascular, cerebrovascular and ureteral disorders are the diseases with a high risk of death all over the world. Thanks to advances in medical devices and biomaterials technologies, significant developments taken place in vascular applications, especially in recent years. For this purpose, vascular stents were developed and produced. A vascular stent is a flexible tube mesh made of metal or polymer which is used for the treatment of vascular occlusion.
To maintain flow in a occluded blood vessel, material which is used in the target region should be expandable. In addition to elasticity or plasticity, elastic recoil resistance, rigidity and chemical / mechanical wear resistance are required for permanent stent applications. Biocompatible metals provide such features and therefore they can be used in stent production. For these purposes; Ni-Ti alloys which are known as shape memory smart materials and stainless steel such as 316L were preferred in the first stent applications. But low corrosion resistance of such materials which are used in the human body leads crevice or pitting corrosion on the stent surface resulting in fracture, so this property is main disadvantage of metallic stents. Additionally, because of the interaction between bare metallic stent and veins, atherosclerosis or restenosis after the implantation may occur.
To preclude such circumstances, Drug-Eluting Stents (DES) have been developed by using biopolymer technology and degrading metals such as Mg alloys. In DES, drug impregnated biopolymer is coated on metallic base. Impregnated chemicals or drugs block or retard plaque formation around biomaterial or vein. Thanks to DES, the risks of atherosclerosis and restenosis after stent implantation have been significantly reduced. However, latterly thrombosis incident is related with DES more than bare-metals because of presence of permanent polymer in DES. In literature, diverse effects have been associated with thrombosis after the DES implantation such as stent apposition, stent related endothelial dysfunction and infection.
Nevertheless, with the usage of biodegradable materials in the stent production, it has been seen that such stents will not cause the problems which occur in permanent bare-metal or polymer materials. But early-degradation risk of biodegradable stents, before the treatment of target vessel is a problem that is needs to be solved.
In future studies, issues such as occlusion, late-time restenosis or atherosclerosis can be prevented by the modification of stent surface or using different materials.
Keywords: Cardiovascular stents, cerebrovascular stents, ureteral stents, bare-metal stents, drug-eluting stents, biodegradable stents