Research Information System
II. International Congress on New Trends in Science, Engineering and Technology, Roma, Italy, 4 - 06 September 2018, pp.8-10, (Summary Text)
The Latest Generation Of Vascular Stents Designs And Past/Future Technological Trends
Abstract: Biomedical technologies are developing in accordance with the needs of human beings. Thanks to the production of new materials, the field of biomaterials has also been significantly improved in recent years. The expandable tube, which is produced from biocompatible materials called stents, is used for the treatment of vascular diseases such as obstruction in human vessels. Different stent designers have used various biomolecules, biopolymers or hybrid biomaterials for more successful results. However, some materials and designs have not been successful enough due to problems such as fracture or chronic thrombosis caused by stenting. In stent production, properties such as material selection, biocompatibility, mechanics, strength and reduced radio-opaque behavior are very important. Cobaltchromium alloys have been used in balloon expandable stents for the first time and molybdenum has also been added to reduce oxidability. A sandwich design consisting of tantalum has been tried between 316L stainless steel in the form of two separate layers to ensure adequate mechanical strength. For a more suitable radio-opaque feature, bare metal stents were coated with gold, but goldcoated materials were also found to cause a higher risk of thrombosis. Coating of the stent with diamond-like-carbon, iridium-oxide or titanium-nitric oxide has been shown to reduce the rate of thrombosis to below 15% by reducing metal-ion release. Reduction of stent-derived thrombosis levels is very important for human health. Researches have shown that geometric design affects the rate of late thrombosis as well as material content. Vascular compatibility can be improved better if the stent is designed as a thinner geometry or coated with a suitable material. Many of the new researches are concerned with overcoming known problems. Main goal of our study is to reduce thrombosis levels resulting from stent biomaterials. It is aimed to obtain a better stent surface which will cause less problems in today's studies. Because of the limited improvement of coatings made with inorganic materials, organic coating methods have begun to be tried. In addition, thanks to polymer and biodegradable material technology, it has been found that the DES (Drug Eluting Stent) has a positive effect on vessel compatibility. It is effective to convert traditional biomaterials into a more slippery state with a structure including a phospholipid polar group by biomimicking a contact surface for making a biopolymer surface more compatible with blood. Polymer-coated stents such as poly-n-butyl-methacrylate, polyvinylidene fluoro-hexafluoropropylene have been used in the design of DES’ since they reduce thrombosis compared to bare-metal stents. Magnesium alloys, polylactic acid, polyglycolic acid and polylactic-co-glycolic acid have been used to produce biodegradable drug-releasing stents. However, research on the improvement of biodegradable material technologies is still continuing thanks to the different organic-polymer coatings that deliver the drug. Each material has its own advantages and disadvantages. While oxidability and ion release are encountered in bare metal materials, low mechanical strength, elastic recoil resistance and early biodegradation time are encountered in magnesium or polymer based DES biodegradable materials. 10 However, the hydrophobic behavior between the body fluid and the stent material can be improved to achieve a thrombosis-inhibiting surface. Continuing scientific studies on intravascular stents will lead to new developments.
Keywords: Vascular Stents, Stent Materials, Restenosis, Late-Thrombosis Biomaterials, Biocompatibility.