Review of stent coating strategies: Clinical insights

Abstract

Despite advances in stent design, expansion techniques and anti-thrombotic agents to improve pharmacological control of subacute thrombosis (SAT) and to reduce to 2 the occlusive thrombosis rates, a significant risk of mortality associated with thrombotic vascular occlusion due to the adhesion of blood constituents remains a problem for patients with more complex lesions. The adhesion process is greatly governed by the surface characteristics, mainly the surface chemical composition, surface morphology, presence of charge, surface wettability and surface roughness. Surface chemical inertness (reduced interaction with chemicals and biological components) subsequently became the primary criteria which guided the development of non thrombotic stents as well as other blood-contacting materials. A number of strategies have been adopted in an effort to coat the stent with or without the use of a drug delivery system, to overcome the thrombus formation, to minimize the stent occlusion and to improve the overall hemocompatibility of the device. This paper aims at reviewing the clinical outcomes of main nonpharmaceutical stent coating procedures and their clinical outcomes. New stents which combine the anti-thrombotic coating with the drug delivery ability, such as radioactive stents, degradable stents and some new challenging trends which are mostly at research and development stage for stent surface coatings are also introduced.

Electrochemical polymerization of pyrrole over AZ31 Mg alloy for biomedical applications

“…These implants have an inadequate mechanical strength when used for load-bearing parts [7]. Compared to the currently approved biomaterials, Mg alloys have many advantages over other materials [8][9][10] as they have high strength/weight ratio with Young's modulus (E) of about 41-45 GPa, which is closer to that of the natural bone (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). Since the E value is closer to natural bone, it minimizes the stress shielding effect and allowing the bone bonding ability.…”

“…Metals and alloys play essential roles in biomedical applications as bone, dental or vascular implants owing to their excellent mechanical properties and corrosion resistance [1][2][3][4][5][6]. The development of biodegradable implants has grown as one of the important areas in medical science, since they can be gradually dissolved, absorbed, consumed, or excreted in human body environment and then disappear spontaneously after the bone tissues heal.…”

Preparation of Hydroxyapatite/Tannic Acid Coating to Enhance the Corrosion Resistance and Cytocompatibility of AZ31 Magnesium Alloys

“…This reduces the economic burden and health risks of patients [2]. Therefore, magnesium alloys have recently attracted attention as an implant material for orthopedic surgery and cardiovascular medicine [4][5][6]. However, magnesium alloys also have a very negative potential and poor corrosion resistance, which influences bone bonding and suppresses their development for biomedical applications [7].…”

A Zr-based bulk metallic glass for future stent applications: Materials properties, finite element modeling, and in vitro human vascular cell response

“…Recently, Shabalovskaya et al evaluated wettability and surface energy of native Nitinol surfaces and their results suggest a positive correlation between the polar component of SFE and the hemocompatibility of Nitinol [57]. In fact, the significance of surface properties is evident from many of the surface modification-based strategies striving to improve vascular stent performances [2,8,58]. …”