18-Month Implant of a Transcatheter Pulmonary Valve Using Bioengineered Tissue Leaflets in Juvenile Sheep

Congenital valve disease, predominantly in the pulmonary position, requires multiple replacements as current bioprosthetic valves degrade and calcify over time. An allogenic, decellularized bioengineered tissue with minimum immune response and calcification would provide an ideal solution for young patients and could substantially improve the standard of care. In this study, a transcatheter pulmonary valve with bioengineered tissue leaflets on a self-expanding nitinol stent was implanted for up to 18 months in five juvenile sheep using an 18Fr transapical delivery system. Serial echo monitoring showed an increase in cardiac output as the juvenile sheep grew without any decrease in effective orifice area (>2 cm2) or increase in pressure gradients (<10 mmHg for both peak and mean). No valvular regurgitation, leaflet thickening, or tissue abnormality was reported at any time points. Micro-CT and histological assessment showed mild calcification and mild thrombosis. The 18-month implants in the highly calcific juvenile sheep model showed no loss of function and no deterioration of the bioengineered tissue, suggesting a suitable alternative leaflet material for younger patients where functional longevity is critical.