Pediatric patients with congenital heart disease requiring valve replacement often must undergo multiple surgeries to implant ever-larger valves because replacement devices cannot grow with a child’s heart. The risk and expense of repeated surgeries might be eliminated with an artificial valve that can be expanded, via a At left, the valve in its unexpanded state; at right, its expanded configuration in a larger heart. Source: Sophie Hofferberth, Boston Children’s Hospital; Lara Tomholt and James Weaver, Wyss Institute for Biologically Inspired Engineeringminimally invasive transcatheter procedure, to accommodate the growing organ and associated increases in blood flow volume.

The prosthetic designed by researchers from Harvard University and Boston Children’s Hospital features two leaflets modeled after the venous valve instead of the three usually attached to commercially available devices. The polymeric leaflets are attached to a stainless steel stent and are mechanically expanded using transcatheter balloon dilation to adapt to larger fluid volumes. The geometry of the new valve is optimized to maintain closure and one-way blood flow even when expanded in diameter.

Size-adaptable bileaflet valves supported forward fluid flow without leaking in flow loops in vitro and maintained function when implanted into growing lambs and mechanically expanded over 10 weeks. The efficient blood flow performance demonstrated could also potentially reduce the risk for blood clot complications that often arise with commercial prosthetic valves.