Progress on a Novel, 3D-Printable Heart Valve Prosthesis

Polymeric Heart Valves: Do They Represent a Reliable Alternative to Current Prosthetic Devices?

With the increasing number of people suffering from heart valve diseases (e.g., stenosis and/or insufficiency), the attention paid to prosthetic heart valves has grown significantly. Developing a prosthetic device that fully replaces the functionality of the native valve remains a huge challenge. Polymeric heart valves (PHVs) represent an appealing option, offering the potential to combine the robustness of mechanical valves with the enhanced biocompatibility of bioprosthetic ones. Over the years, novel biomaterials (such as promising new polymers and nanocomposites) and innovative designs have been explored for possible applications in manufacturing PHVs. This work provides a comprehensive overview of PHVs' evolution in terms of materials, design, and fabrication techniques, including in vitro and in vivo studies. Moreover, it addresses the drawbacks associated with PHV implementation, such as their limited biocompatibility and propensity for sudden failure in vivo. Future directions for further development are presented. Notably, PHVs can be particularly relevant for transcatheter application, the most recent minimally invasive approach for heart valve replacement. Despite current challenges, PHVs represent a promising area of research with the potential to revolutionize the treatment of heart valve diseases, offering more durable and less invasive solutions for patients.

A Novel Polymer Film to Develop Heart Valve Prostheses

Polymer heart valves are a promising alternative to bioprostheses, the use of which is limited by the risks of calcific deterioration of devitalized preserved animal tissues. This is especially relevant in connection with the increasingly widespread use of transcatheter valves. Advances in modern organic chemistry provide a wide range of polymers that can replace biological material in the production of valve prostheses. In this work, the main properties of REPEREN® polymer film, synthesized from methacrylic oligomers reinforced with ultra-thin (50 µm) polyamide fibers, are studied. The film structure was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The hydrophilicity and cytocompatibility with EA.hy926 endothelial cells were assessed, and a hemocompatibility evaluation was carried out by studying the platelet aggregation and adhesion upon contact of the REPEREN® with blood. The mechanical behavior and biocompatibility (subcutaneous implantation in rats for up to 90 days, followed by a histological examination) were studied in comparison with a bovine pericardium (BP) cross-linked with an ethylene glycol diglycidyl ether (DE). The results showed that REPEREN® films have two surfaces with a different relief, smooth and rough. The rough surface is more hydrophilic, hemo- and cytocompatible. Compared with the DE-BP, REPEREN® has a higher ultimate tensile stress and better biocompatibility when implanted subcutaneously in rats. The key properties of REPEREN® showed its potential for the development of a polymeric heart valve. Further studies should be devoted to assessing the durability of REPEREN® valves and evaluating their function during orthotopic implantation in large animals.

Aortic Valve Engineering Advancements: Precision Tuning with Laser Sintering Additive Manufacturing of TPU/TPE Submillimeter Membranes

Synthetic biomaterials play a crucial role in developing tissue-engineered heart valves (TEHVs) due to their versatile mechanical properties. Achieving the right balance between mechanical strength and manufacturability is essential. Thermoplastic polyurethanes (TPUs) and elastomers (TPEs) garner significant attention for TEHV applications due to their notable stability, fatigue resistance, and customizable properties such as shear strength and elasticity. This study explores the additive manufacturing technique of selective laser sintering (SLS) for TPUs and TPEs to optimize process parameters to balance flexibility and strength, mimicking aortic valve tissue properties. Additionally, it aims to assess the feasibility of printing aortic valve models with submillimeter membranes. The results demonstrate that the SLS-TPU/TPE technique can produce micrometric valve structures with soft shape memory properties, resembling aortic tissue in strength, flexibility, and fineness. These models show promise for surgical training and manipulation, display intriguing echogenicity properties, and can potentially be personalized to shape biocompatible valve substitutes.