In-vitro hemodynamic testing of stentless prosthetic aortic valves.
Ng, Daniel Wai Hung.
Neo, Si Yang.
Ng, Chung Liu.
Wong, Benedict Jun Shuan.
School/DeptSchool of Mechanical and Aeronautical Engineering
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When a native aortic valve becomes severely diseased, either stenotic or incompetent, a replacement valve is necessary. This replacement valve can be in the form of a mechanical heart valve or tissue heart valve. Mechanical valves usually made from metal and fabrics are very durable but they have poor hemodynamic and are thrombogenic requiring permanent anticoagulation. Tissue heart valves constructed from biological tissues have excellent hemodynamic blood flow, but they lack durability. The project proposed a new valve design that is similar to a stentless tissue valve but made from a synthetic material, Polytetrafluoroethylene (PTFE). A PTFE valve combines the benefits of both tissue and mechanical valves. PTFE can be moulded into the shape of the native valve, thus providing excellent blood flow dynamics and minimum leakage similar to the tissue valves. A PTFE valve also has the advantage of mechanical valves of having good structural durability. The PTFE valve also adopts the stentless valve concept by incorporating the single point attached commissures (SPAC) implantation technique. Stentless means that the tissue forming the valve do not have a rigid frame to prop up or support the valve leaflet. The stentless valve concept with the SPAC technique is expected to greatly simplify the implantation procedure. The objective of this Final Year Project is to compare the hemodynamic performance between the PTFE valve and the pericardial valve using a pulsatile flow test loop. The scope of this project includes designing a fixture to accommodate the valves in the Vivitro System and studying hemodynamic parameters such as pressure drop, flow rate, and dynamic leaflet behaviour of the valves. A new fixture was successfully fabricated for the stentless SPAC valve. Tests were done to evaluate the hemodynamic performance of the PTFE valve in comparison to the pericardial valve. From the results obtained through various testing, the pericardial valve has better hemodynamic performance and leaflet behaviour due to a larger valve opening area and more flexible leaflets while the PTFE valve has superior durability. More tests should be done in order to further support the conclusion.
Project Code: MAE-16714
Diploma in Bioengineering (DBEN)
Supervisor: Xiong, Fang Li.