Optimization based on finite element technique of nitinol stent / 中国医疗器械杂志

The finite element method was used for simulating the mechanical performance and fatigue safety of three different structures of Nitinol stent. According to the actual situation, after proposing reasonable assumptions and simplification, the geometry model and finite element model establishment, material mode selection and boundary condition setting are completed. The strain and fatigue life of different stent edges wide (omega) or strut angle (theta) are computed. The result can provide a valuable reference for the optimal design of stent.

Finite element analysis for compression and expansion behavior of magnesium stent / 中国医疗器械杂志

Magnesium stents have gained increasing interest as an ideal stent of future intervention. In order to study the deformation behavior of magnesium alloy stents in the interventional treatment, the finite element method was used to analysis the effects of different crimp and expansion dimensions on the mechanical properties (maximum stress, radial recoil rate, longitudinal shortening rate and radial strength). The results showed that crimping and expanding have a minimal influence on the stent radial strength. When the expansion size is same, the maximum equivalent stress and recoil rate decrease with the crimp size. When the crimp size is same, in contrast with the radial recoil rate, the maximum equivalent stress and longitudinal shortening rate increase with the expansion size. In addition the paper verified the radial strength-radial displacement curve obtained by FEM. Results are basically consistent, indicating the finite element method can efficiently provide researchers with reliable, high-quality design.

Related research on mechanical property of valve membrane in transcatheter bioprosthesis valve based on the chemical modification and cutting technology / 生物医学工程学杂志

The aim of this research is to investigate the preparation method of valve membrane in transcatheter bio- prosthetic valve, and to study the effect of chemical modification and cutting technology to tensile property and suture force property of valve membrane. We carried out a series of processes to perform the tests, such as firstly to test the crosslinking degree of valve membrane using ninhydrin method, then to test the tensile property and suture force property by using Instron's biomechanicAl testing equipment, and then to observe the collagen fiber orientation in valve membrane using Instron's biomechanical testing equipment and using field emission scanning electron microscopy. The study indicated that after the chemical modification, the crosslinking degree, tensile strength and suture force strength increasing rate of valve membrane were 93.78% ± 3. 2%, (8.24 ± 0.79) MPa, 102%, respectively. The valve membrane had a better biomechanical property and would be expected to become valve membrane in transcatheter bioprosthesis valve.

Application status and prospects of thrombectomy devices for acute ischemic stroke / 中国医疗器械杂志

The character and application status of interventional thrombectomy devices for acute ischemic stroke (AIS) are briefly introduced and the development trend is also analyzed.

Fatigue life analysis of coronary stent by finite element analysis / 医用生物力学

Objective After the implantation,coronary stent is expected at least to keep its integrity and maintain the predicated function for over 10 years or 4e8 cycles under the pulsatile loading conditions,so the fatigue property of the stent should be evaluated.Method The finite method was used to analyze the stress distribution of different phases and evaluate the fatigue life according to Goodman criteria,meanwhile,the accelerated fatigue experiment was also performed.Results It can be concluded that the dangerous points are all but located in the lateral inner surface of stent curvature.Conclusions The results prove that the fatigue property can be simulated through the finite element analysis,which can provide the theoretical guidance for the stent design.

Treatment of distal internal carotid artery aneurysm with the willis covered stent: a prospective pilot study / 介入放射学杂志

Objective To evaluate the flexibility and efficacy of the Willis covered stent in the treatment of distal internal carotid artery(DICA)aneurysms.Methods The study was approved by the anthors' institutional review board,and the research was conducted by the authors' institution and the MicroPort Medical Company(Shanghai,China).Thirty-one patients with 33 DICA aneurysms were considered for treatment with a Willis covered stent.The angiographic assessments were categorized as complete or incomplete occlusion.The data on technical Success,initial and final angiographic results,mortality,morbidity,and final clinical outcome were collected,and follow-up was performed at 1,3,6,and 12 months and yearly after the procedures.Results Navigation and deployment of the covered stents were succssfnl in 97.6%(41 of 42;95%confidence interval[CI]:93%,102%)of the attempted stent placement procedures.The initial angiographic results showed a complete occlusion in 23 patients with 25 aneurysms(of 32 aneurysms,78.1%[95%CI:63%,93%])and an incomplete occlusion in seven patients with seven aneurysms(21.9%).The angiographic follow-up(mean,14 months[95% CI:12,15 months])findings exhibited a complete occlusion in 27 patients with 29 aneurysms(of 31 aneurysms,93.5%[95%CI:84%,103%])and an incomplete occlusion in two aneurysms(6.5%),with a mild in-stent stenosis in two patients.The clinical follow-up(mean,27 months[95% CI:23,30 months])demonstrated that 15 patients experienced a full recovery and 14 patients improved.Conclusion The preliminary results demonstrate good flexibility and efficacy of the Willis covered stent in the treatment of DICA aneurysms in selected patients:longer follow-up and expanded clinical trials are needed.