In silico assessment of a compliant vascular prosthesis

• Main Author: Wong, Yi Jean
• Other Authors: Subbu S. Venkatraman
• Format: Final Year Project
• Language: English
• Published: 2018
• Subjects: DRNTU::Engineering::Materials::Biomaterials
• Online Access: http://hdl.handle.net/10356/73733
• Institution: Nanyang Technological University

Coronary heart disease is one of the most common disease in the world causing about 30% of deaths per year. The main cause is resulted from the narrowing of blood vessels due to the accumulation of fatty material within a plaque on the inner walls of the coronary artery. The plaque gradually blocks the blood flow to the ventricular muscle. For many years, Stenting and Coronary Artery Bypass Grafting (CABG) have been the treatment for coronary heart disease. However, complications such as infection and excessive bleeding can occur at the site of catheter insertion of stent. Despite the presence of metal stents, restenosis will occur to about 15% to 30% of the patients. Some patients require more than one bypass grafts or do not have suitable autologous vessels for this procedure. Therefore, an effective smaller diameter vascular prosthesis is required for these patients. Vascular graft failure can be influenced by the mismatch in compliance where it depends on the relation between pressure and diameter. With the aim to minimise the mismatch, PCL and PLC are two main materials used in the fabrication of vascular prosthesis. It was hypothesised that the design of the fiber will have an effect on the mechanical properties of the fiber. The behaviour of how the PCL fiber extends as it is pulled under a certain loading was studied using Nastran-In CAD, a Finite Element Analysis programme. Specifically, non-linear static analysis was carried out to find out how the design of the fiber and elastic modulus of the material used can affect the mechanical properties. Vascular prosthesis will be fabricated by dip-coating, followed by 3D printing. Compliance test will also be done to have a comparison between the fibers fabricated and the native blood vessel to observe the physical changes when the vascular prosthesis are placed in a “physiological-like” environment. Results have shown that the design of the fiber indeed has an effect on mechanical properties, in particular the von Mises Stress. A property where the material will result in failure if the value of the maximum von Mises Stress is greater than the maximum stress of the material. Furthermore, both Finite Element Analysis and compliance test have shown that although PCL is an excellent biomaterial, due to the elastic modulus of PCL, the prosthesis has low compliance as regards the mismatch with native blood vessel. It has postulated that PCL may not be a suitable mesh material as the compliance of a native blood vessel is high.