Adjustable Heart Valve May Accommodate Growth in Children

By David Douglas

February 27, 2020

NEW YORK (Reuters Health) - Unlike current fixed prosthetic valves for children with congenital heart disease, an experimental geometrically adaptable heart valve replacement may allow them to reach adulthood with a single valve, according to preclinical testing.

"To address the limitations of existing fixed diameter valve replacement devices, we mimicked the geometry of the human venous valve to design a size-adjustable heart valve that is able to accommodate growth and changing heart dimensions, while maintaining optimal performance," Dr. Sophie C. Hofferberth of Boston Children's Hospital told Reuters Health by email

During development, Dr. Hofferberth and colleagues did benchtop studies to examine how the varying aspect ratios of their stent design could achieve radial expansion without compromising valve function. They also ran computer simulations and tested their biomimetic bileaflet prosthetic valve implant in animals.

Juvenile sheep successfully underwent transcatheter balloon dilation of the valve implant at three separate time points. Lambs displayed expected growth profiles gaining more than 60% in body weight and their prosthetic valves achieved an internal diameter 1.6 times that of the initial setting.

There was no chronic anticoagulant or antiplatelet therapy administered, and yet at necropsy the inflow and outflow surfaces of all explanted valves had minimal tissue ingrowth and were free of thrombus, the researchers report in Science Translational Medicine.

"A shortcoming of many existing devices is the presence of flow disruptions that lead to blood clot formation and early valve deterioration," Dr. Hofferberth said in a statement, "Our design achieves a favorable flow profile that seems to facilitate effective valve washout and minimize flow stagnation, which is likely to be an important determinant of long-term device durability."

The researchers say their "study has limitations and that further work is required to advance this technology toward clinical translation."

In an email to Reuter Health, Dr. Hofferberth noted, "The ability to expand the valve also has potential implications for adult patients, where recovery of heart function after valve replacement often leads to flow restriction through fixed-diameter devices. Our size-adjustable design could eliminate this problem, by allowing for flow-adjustment after implantation."

The study did not have commercial funding. Dr. Hofferberth and several coauthors have filed a provisional patent application related to the device.

SOURCE: Science Translational Medicine, online February 19, 2020.