Document Type : Original Article
Biomedical Engineering Department, University of Technology, Iraq
Heart valve replacement is a major health burden and is required by millions of people worldwide, which invites the continuous need to discover and manufacture more effective and permanent artificial replacements. In the present work, unique models of eight artificial heart valves were designed and examined using seven synthetic and nanocomposite materials. The designed valves were examined to determine the best designs and materials in terms of durability, flexibility, and energy consumption, and to improve the biomechanical performance by using the Response Surface Methodology (RSM) and the Design Expert System 13. The highest values of the equivalent stress due to the applied blood pressure on the moving parts on each type of manufactured heart valve occur in valves with three dimensions moving parts, reached in the mitral tri-leaflet valve 14.13 MPa, followed by the tricuspid aortic valve. The equivalent stresses for other types of valves produced with simple surface action were lower than 2 MPa. The strain energy that is expended during the process of diastole and systole was found to be directly proportional to the strength and flexibility of the materials used. The energy consumption rates decrease when using highly elastic materials such as TPE and PSN4. The values of this energy also increase with an increase in the area of the moving parts of the valve, especially when faced with the process of closing blood flow, as with the use of the tricuspid aortic valve (TAV). The highest total deformation resulted in the valve body when using TPU, followed by TPE, nylon, PETG, and PLA, while the lowest deformation rates were observed when using PSN4, which ranged from 5x105 to 0.1 mm, followed by SIBSTAR103 nanostructured rubber. The obtained values of stress safety factors were decreased with the complexity of the movement for the moving parts of the valve. The highest rates were recorded when using the tricuspid mitral valve, reaching 2.45 when using the high-strength and flexible PSN4 nanomaterial. It can be concluded that the best materials for manufacturing these four types of valves are the PSN4, followed by SIBSTAR103T, TPU, and TPE. The use of PETG, PLA, and nylon materials is not recommended for the manufacture of any prosthetic heart valves, due to their lack of strength, flexibility, and high brittleness, especially for PETG and PLA materials. It was also noted here that PSN4 is the only material suitable for the manufacture of mitral tri-leaflet and tricuspid mitral valve artificial valves. For other types of valves manufactured with a single leaflet, high safety stress factors were obtained because their movement is simple, flat, and in one direction, where the highest values were observed when testing a single hemispherical leaflet type valve, then the conical caged ball and the caged ball type, respectively.