DESIGN AND CHARACTERIZATION OF A PATIENT-CUSTOMIZABLE POLYMERIC CARDIAC VALVE PROSTHESIS FOR SURGICAL OR TRANSCATHETER IMPLANTATION

Background: Cardiac prostheses have transformed the management of patients with valvular diseases. However, a major drawback of both mechanical and biological prostheses is their inability to be customized to the individual patient's anatomy. This can lead to complications such as leakage or poor fit. Polymeric cardiac valve prostheses represent a promising alternative, as they can be perfectly customized and easily produced on a large scale. The aim of this study is to design such prostheses using polymer materials.
METHODS AND RESULTS: We created a 3D model of a heart valve using computer-aided design (CAD) software, Catia V5. The molds were printed using High Temp resin on a FormLabs 3 3D printer with a resolution of 0.025mm. We produced valve prototypes by molding polyvinyl alcohol (PVA) hydrogel made from 125 kDa PVA (Selvol 125, Sekisui) dissolved in water at a 15% mass concentration. The physical cross-linking was done through four cycles of 16 hours at -20°C and 8 hours at 4°C, using freeze-thawing. The valves (see figure 1) were mounted on a resin support using Loctite 406 glue.
We performed leak testing under hydrostatic conditions using a column of water, ranging from 0 to 100mmHg. The results showed a negligible leak rate of 58 mL/min (see figure 2) when exposed to the maximum tested pressure of 100 mmHg, which is much lower than what is observed in healthy humans. We also conducted strain-stress testing to characterize the mechanical properties of the material, using a Mach-1 mechanical tester (Biomomentum Inc.). The results of the tensile strength test showed that the maximum stress the material could withstand while being stretched, was 160 kPA, which is about an order of magnitude lower than the pericardium used for bioprostheses.
Conclusion: PVA-based hydrogels are promising materials for the design of polymeric heart valves. They possess desirable mechanical properties, versatility, and ease of fabrication, making them suitable for the production of custom-made valves in a range of sizes and shapes. This represents a significant advancement in personalized medicine. Additionally, different components and cross-linking agents can be incorporated with PVA to enhance its mechanical properties and ensure long-term durability in vivo. This can be assessed through durability, calcification, and hemocompatibility testing.