title: Enhancement of Mechanical Properties and Testing of Nitinol Stents in Cerebral Aneurysm Simulation Models.
abstract: Stents are promising medical devices widely used in the prevention of cerebral aneurysm rupture. As the performance of stents depends on their mechanical properties and cell configuration, the aim of this study was to optimize the stent design and test the hemodynamic properties by using computational solid mechanics and computational fluid dynamics. In order to test their performance, computer-based cerebral aneurysm models that mimic the conditions present after implantation into the human brain were tested. The strut configuration selected was the closed-cell type, and nitinol was chosen as the material for stent manufacture because the innate characteristics of this material increase stent flexibility. Three ideal sample stent types with different cell configurations were manufactured. Computational solid mechanics analysis of the sample stents showed over 30% difference in flexibility between stents. Furthermore, using a cerebral aneurysm model simulation, we found that the stents eased the hemodynamic factors of the cerebral aneurysm and lessened the flow velocity influx into the sac. A decrease in flow velocity led to a 50-60% reduction in wall shear stress, which is expected to prevent aneurysm rupture under clinical conditions. Stent design optimization was carried out by simulation and electropolishing. Corrosion resistance and surface roughness were evaluated after electropolishing performed under variable conditions, but 40 V and 10 s were the most optimal.
authors.affiliation: Department of Medical Sciences, Graduate School of Medicine, Korea University, Seoul, Korea.
authors.forename: Hyo Geun
authors.initials: HG
authors.lastname: Nam
authors.affiliation: Department of Medical Sciences, Graduate School of Medicine, Korea University, Seoul, Korea.
authors.forename: Chang Min
authors.initials: CM
authors.lastname: Yoo
authors.affiliation: Department of Medical Sciences, Graduate School of Medicine, Korea University, Seoul, Korea.
authors.forename: Seoung Min
authors.initials: SM
authors.lastname: Baek
authors.affiliation: Department of Mechanical Engineering, Dankook University, Yongin, Korea.
authors.forename: Han Ki
authors.initials: HK
authors.lastname: Kim
authors.affiliation: Department of Medical Sciences, Graduate School of Medicine, Korea University, Seoul, Korea.
authors.forename: Jae Hee
authors.initials: JH
authors.lastname: Shin
authors.affiliation: Department of Medical Sciences, Graduate School of Medicine, Korea University, Seoul, Korea.
authors.forename: Min Ho
authors.initials: MH
authors.lastname: Hwang
authors.affiliation: Department of Medical Sciences, Graduate School of Medicine, Korea University, Seoul, Korea.
authors.forename: Ga Eun
authors.initials: GE
authors.lastname: Jo
authors.affiliation: Department of Medical Sciences, Graduate School of Medicine, Korea University, Seoul, Korea.
authors.forename: Kyong Soo
authors.initials: KS
authors.lastname: Kim
authors.affiliation: College of Medicine, Radiation Applied Life Science, Seoul National University, Seoul, Korea.
authors.forename: Jae Hwa
authors.initials: JH
authors.lastname: Cho
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, College of Medicine, Korea University, Seoul, Korea.
authors.forename: Seung Hoon
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Department of Radiological Science, Eulji University, Seongnam, Korea.
authors.forename: Ho Chul
authors.initials: HC
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, College of Medicine, Korea University, Seoul, Korea.
authors.forename: Chun Hak
authors.initials: CH
authors.lastname: Lim
authors.affiliation: Department of Medical Sciences, Graduate School of Medicine, Korea University, Seoul, Korea.
authors.forename: Hyuk
authors.initials: H
authors.lastname: Choi
authors.affiliation: Thoracic and Cardiovascular Surgery, College of Medicine, Korea University, Seoul, Korea.
authors.forename: Kyung
authors.initials: K
authors.lastname: Sun
mesh_terms: D000497:Alloys / Q000737:chemistry*; D001783:Blood Flow Velocity; D002560:Cerebrovascular Circulation; D003198:Computer Simulation; D017076:Computer-Aided Design; D004548:Elasticity; D057510:Endovascular Procedures / Q000295:instrumentation*; D006439:Hemodynamics; D006801:Humans; D002532:Intracranial Aneurysm / Q000503:physiopathology / Q000628:therapy*; D008422:Materials Testing; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D011475:Prosthesis Failure; D015607:Stents; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D000497:Alloys; C013616:nitinol
keywords: Closed-cell type; Computational fluid dynamics; Electropolishing; Nickel-titanium shape memory alloys; Stent