Development of New Shapes for Polymeric Heart Valves Using Silicone 3D Printing

Background: Polymeric heart valves aim to unify the advantageous hemodynamic of biological with the longevity of mechanical prostheses by using flexible synthetic materials. Besides mimicking the natural form of the heart valve, the new shapes and functioning principles can be explored to better address the physical properties of these polymers. The rapid development of 3D printing, including options to print in silicone has given us the tools to create, test and improve these new types in yet unknown speed. We created several improved prototypes of the TIPI valve based on the PIZZA valve (patent number DE 10 2008 012 438 B4) as well as of the TRISKELION another construction principle developed in our institution. These were then tested, compared and further developed.

Method: STL files of prototypes were designed and printed in silicones of either shore 35 or 65 using a special 3D printer. Depending on the valve type restrictors were constructed from metal wire and support structures printed in solid plastics. Prototypes were then tested using a hemodynamic pulse duplicator simulating 70 bpm and 70 mL stroke volume (cardiac output 4.9 L/min). Valve opening cycles were visualized with a high-speed camera. The resulting values were compared with a standard bioprostheses and a mechanical valve.

Results: After several improvement steps, three polymeric prototypes reached significantly improved performance characteristics nearing the values of biological and mechanical types measured in our setup. Regurgitation factions were at 20.83 ± 10.88% (TIPI 4.4), 18.39 ± 2.07% (TIPI 6.2), 32.85 ± 5.78% (TRISKELION 2) compared with 8.79 ± 0.3% (biological), and 13.23 ± 0.66% (mechanical). Mean systolic pressure gradients were 16.82 ± 0.86 mm Hg (TIPI 4.4), 7.71 ± 0.41 mm Hg (TIPI 6.2), 7.31 ± 0.73 mm Hg (TRISKELION 2), 8.18 ± 0.9 mm Hg (biological), 10.53 ± 0.63 mm Hg (mechanical).

Conclusion: The development of non-biological heart valve prostheses suitable for transcatheter implantation is of high interest due to the remaining problem of valve degeneration in commonly used bioprostheses. The further improvement of existing and newly emerging prototypes created by 3D printing in silicone allow for rapid development and research of the optimal physical shape of polymeric valves. Following this, these shapes and construction principles can be transferred into modern, highly biocompatible polymers like POSS-PCU.

Publication History

Article published online:
03 February 2022