In vitro hydrodynamic evaluation of a biovalve with stent (tubular leaflet type) for transcatheter pulmonary valve implantation.

We have been developing an autologous heart valve-shaped tissue with a stent (stent-biovalve) for transcatheter pulmonary valve implantation (TPVI) using "in-body tissue architecture" technology. In this study, the hydrodynamic performance of a stent-biovalve with tubular leaflets was evaluated by changing its leaflet height in an in vitro test in order to determine the appropriate stent-biovalve form for the pulmonary valve. A specially designed, self-expandable, stent-mounted, cylindrical acrylic mold was placed in a dorsal subcutaneous pouch of goat, and the implant was extracted 2 months later. Only the cylindrical acrylic mold was removed from the implant, and a tubular hollow structure of membranous connective tissue impregnated with the stent strut was obtained. Half of tubular tissue was completely folded in half inwards, and 3 commissure parts were connected to form 3 leaflets, resulting in the preparation of a stent-biovalve with tubular leaflets (25-mm ID). The stent-biovalve with adjusting leaflet height (13, 14, 15, 17, 20, and 25 mm) was fixed to a specially designed pulsatile mock circulation circuit under pulmonary valve conditions using 37 °C saline. The mean pressure difference and effective orifice area were better than those of the biological valve. The lowest and highest leaflet heights had a high regurgitation rate due to lack of coaptation or prevention of leaflet movement, respectively. The lowest regurgitation (ca. 11%) was observed at a height of 15 mm. The leaflet height was found to significantly affect the hydrodynamics of stent-biovalves, and the existence of an appropriate leaflet height became clear.