In children with congenital pulmonary valve disease, the flow of blood between the heart and lungs is impeded. In cases where the pulmonary valves have narrowed or are leaking and cannot be treated effectively with a catheter, surgeons generally replace them with a prosthetic valve. However, the current prosthetic pulmonary valves are adult-sized and have a fixed diameter, as a result of which they must be replaced as the child grows up. Now, for the first time, a prosthetic pulmonary valve replacement specifically designed for pediatric patients can expand over time inside a child’s anatomy. The valve can be fitted to the child’s individual body size and also adjusted for size if required through a minimally-invasive transcatheter balloon dilation procedure to maintain blood flow. This could eliminate the need to perform invasive replacement surgeries every few years as the child will not require another replacement procedure until reaching adulthood.

The revolutionary device, known as the Autus Valve, was invented at Boston Children’s Hospital (Boston, MA, USA) and was first implanted in a young patient in late 2021 as part of a collaborative clinical study. In commercially available prosthetic heart valves, there are three leaflets that operate as flaps for controlling blood flow, thereby imitating the tri-leaflet structure of the human aortic valve. For developing the heart valve, the researchers drew inspiration from a device that mimicked the bi-leaflet function of a venous valve in leg veins, as its two elastic flaps possess the perfect geometry for maintaining proper closure and one-way blood flow even after the veins in the leg expand in diameter. The team believed that this process could also work in the heart and went on to study the geometric profile of the human venous valve while using this as the basis for creating a valve prototype.

The researchers conducted studies in which they implanted prototypes of the replacement pulmonary valve in growing lambs and found that the device can be fitted and then expanded in sync along with the growth of heart anatomy. They also found that the valve could successfully maintain the control of blood flow without stretching and compromising the device’s frame or material. The two leaflets in the device are made of a polymer which has a long track record of use as a pediatric pulmonary valve leaflet. Before being implanted, doctors can adjust the valve diameter to match a patient’s heart anatomy. After the device is implanted, cardiac catheterization specialists can expand the valve if it becomes too small after a child’s grows quickly by using a catheter balloon. Using an echocardiogram, doctors can assess the valve’s integrity and how well it is controlling the flow of blood. Boston Children’s is now conducting US FDA-approved early clinical studies to examine the valve’s effectiveness in children aged between 2 to 11 years. The initial study will be followed by a larger clinical trial, with the aim of seeking FDA approval for making the device commercially available.

“It’s exciting and incredibly motivating that we’re at the stage where we can actually see the device helping patients,” said the device’s inventor, Sophie-Charlotte Hofferberth, MD. “If a valve expansion is needed after the device is implanted, we anticipate a child would recover from the procedure within a few hours,”

“There is a huge need for better solutions for children with valve disease,” Hofferberth added. “A pulmonary valve that can be adjusted for size could give young patients a bridge through childhood and have a huge impact on their long-term quality of life.” 

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