Small patients - Big needs: A material-based approach to develop miniaturised valves for congenital heart diseases.

Paediatric valve replacements cannot be built by simply scaling down bigger-sized valve implants. Innovative approaches that combine novel material systems, processing technologies, and device designs are needed to develop adaptable, durable, and biocompatible miniaturised solutions tailored to the paediatric population with congenital heart diseases. In response to that medical need, in this work, we have developed miniaturised valves following a biohybrid approach that combines synthetic components with bioinspired materials to exploit the optimal properties of each. Specifically, the valve was composed of (i) an electrospun synthetic polymer to provide stability, (ii) protein-engineered elastin to ensure flexibility and low thrombogenicity, and (iii) a tailor-made stent to enable minimally invasive implantation. Our valve implant demonstrated outstanding maximum strain values over 300 %, maximum stresses exceeding 6 MPa, and the ability to withstand burst pressures over 1000 mmHg. Blood compatibility tests revealed lower platelet activation than ePTFE, which is a material used in clinical applications. The hydrodynamics of the miniaturised valve met the standards outlined in the ISO guidelines with regurgitation fractions below 15 % and complete valve closure, indicating excellent functionality. Overall, we have established a material-based approach to address the clinical demand for small valves for children suffering from congenital heart diseases.