An aneurysm is a balloon-like bulge in the wall of blood vessels, occurring in major arteries from the heart and brain. Biodegradable stent-assisted coiling is expected to be the ideal treatment of wide-neck complex aneurysms. A number of biodegradable stents are promising, but also with issues and/or several limitations to be addressed. From the design point of view, biodegradable stents are typically designed without structure optimization. The drawbacks of these stents often cause weaker mechanical properties than native arterial vessels. From the fabrication point of view, the conventional methods of the fabricating stent are time-consuming and expensive, and also lack precise control over the stent microstructure. As an emerging fabrication technique, dispensing-based rapid prototyping (DBRP) allows for more accurate control over the scaffold microstructure, thus facilitating the fabrication of stents as designed.
This thesis is aimed at developing methods for fabrication and optimal design of biodegradable stents for treating aneurysms. Firstly, a method was developed to fabricate biodegradable stents by using the DBRP technique. Then, a compression test was carried out to characterize the radial deformation of the stents fabricated. The results illustrated the stent with a zigzag structure has a higher radial stiffness than the one with a coil structure. On this basis, the stent with a zigzag structure was chosen to develop a finite element model for simulating the real compression tests. The result showed the finite element model of biodegradable stents is acceptable within a range of radial deformation around 20%. Furthermore, an optimization of the zigzag structure was performed with ANSYS DesignXplorer, and the results indicated that the total deformation could be decreased by 35% by optimizing the structure parameters, which would represent a significant advance of the radial stiffness of biodegradable stents. Finally, the optimized stent was used to investigate its deformation in a blood vessel. The deformation is found to be 0.25 mm in the simulation, and the rigidity of biodegradable stents is 7.22%, which is able to support the blood vessel all. It is illustrated that the finite element analysis indeed helps in designing stents with new structures and therefore improved mechanical properties.
| Identifer | oai:union.ndltd.org:USASK/oai:ecommons.usask.ca:10388/ETD-2016-03-2476 |
| Date | 2016 March 1900 |
| Contributors | Chen, Daniel, Kelly, Michael |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text, thesis |
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