Novel Stent Design for Intraoperatively Manufactured Autologous Transcatheter Pulmonary Valve Replacement for Adults and Children

Background: Standard materials for transcatheter heart valve replacements (THVR) are currently limited to heterologous tissue. To overcome persistent constraints, namely the limited lifetime and lack of somatic growth, a novel method to intraoperatively manufacture an autologous THVR has been developed (Schmitt et al, Thorac Cardiovasc Surg, 2023). Combined with bioresorbable stent material, the technique shows promising results for treatment of children. However, intraoperative manufacturing implies new requirements for stent design as the need of sufficient suture points for heart valve attachment.

Methods: We conducted a comparative geometry study on a bioresorbable stent for THVR suitable for children by means of computer-aided design and finite element analysis (FEA). Development focused on feasibility of valve integration (suture point location and number) and deformation behavior (crimpability, expandability). A prototype was used for THVR manufacturing and in vitro testing in a pulse duplicator system under pediatric conditions.

Results: The initial variants were a 12- and 15-crown closed-cell stent. Closed-cell design and crown multiple of three ensure uniform dilatation for a trileaflet valve. The 15-crown design offers more suture points (12 vs. 10 per leaflet) but has a larger minimum crimp diameter. Since further increase in crown number impairs the crimp diameter, we developed a novel stent design with more suture points by adding auxiliary fixation elements in the 12-crown design. The position, number and shape of the auxiliary elements was iteratively improved. The resulting design has an optimized folded shape and provides at least 15 suture points per leaflet, which is comparable to the Ozaki technique (Baird et al., Indian J Thorac Cardiovasc Surg, 2020) and allows for intraoperative THVR manufacturing. We verified the novel stent design by prototype testing. The integration of the valve was feasible. Crimp and dilatation behavior were as predicted by FEA. In-vitro testing showed a fully functional valve with good closing behavior and low regurgitation. In future investigations, we will further optimize the stent design and evaluate long-term properties of the proposed TVHR.

Conclusion: The novel stent design is suitable for manufacturing of THVR for children made of autologous material. By integration of auxiliary fixation elements, the number of suture points for valve attachment has been optimized while minimizing the crimp diameter.

Publication History

Article published online:
13 February 2024