Infants with heart defects in their lower chamber need to undergo several invasive surgeries early on. The first surgery involves implanting in a plastic tube called a shunt to help blood flow. This shunt needs to be replaced with a growing body of children.
Scientists have created a shunt that can expand with light to reduce the number of open-chest surgeries these children receive.
Through this study, scientists aim to expand the inside of the tube with a light-emitting catheter that needs to be inserted within the shunt. This will eliminate the need for additional surgeries.
Congenital heart defects affect the heart’s ventricles. This restricts blood flow to the lungs and other body parts. Children with these conditions cannot survive without surgeries.
Often born undersized, children can increase after their first shunt implantation surgery. To keep up with their growth, they need to undergo more surgeries to replace the shunt.
In a study of 360 patients who underwent the initial heart reconstruction procedure, 41 needed additional surgeries to implant a more significant shunt, and seven died as a result.
Previously, scientists created an expandable prototype to replace the most common shunt type. They coated the inside of the shunt with a unique hydrogel made of water-filled polymers linked by crosslinks. When new crosslinks form, they push water out of the hydrogel, causing it to shrink and the shunt’s interior to expand. In their first design, the crosslinks formed independently without needing an external trigger.
Scientists have now re-engineered the shunt for safer clinical use so that it can be adjusted to meet the needs of individual children. They accomplished this by developing new polymers for a hydrogel that would form new crosslinks and increase the shunt’s inner diameter in response to a trigger.
To start crosslinking, scientists decided to use blue light as this wavelength carries enough energy to initiate the reaction but is safe for living tissue.
Christopher Rodell presented the research and said, “Light has always been one of my favorite triggers because you can control when and where you apply it.”
Scientists use a fiber-optic catheter for the new device, essentially a long, thin tube with a light-emitting tip. To activate the light-sensitive hydrogel in the shunt, surgeons plan to insert a catheter through an artery near the baby’s armpit and guide it into place. This method would avoid the need for opening the baby’s chest.
Credit
Akari Seiner and Christopher Rodell
In lab tests, they discovered that the shunt could be expanded gradually based on how long it was exposed to light. This means that after implantation, the shunt can be adjusted to fit each child’s needs. They increased the shunt’s diameter from 3.5 to 5 millimeters, nearly matching the size of the largest shunts used in children. They also checked how blood cells and vessels reacted to the shunt and found no signs of blood clots, inflammation, or other health issues.
Scientists plan to test full-length shunt prototypes in an artificial set-up mimicking the human circulatory system. If the experiments are successful, they will move on to animal experiments.
Rodell said, “This technology could be useful beyond single-ventricle heart disorders. Surgeons could, for example, use similar tubes to replace blood vessels in children injured in a car accident.”
“In these procedures, you encounter the same problem: Children aren’t just tiny adults; they continue to grow. We need to account for that in biomaterials, how that graft will behave over time.”
The researchers will present their results at the fall meeting of the American Chemical Society (ACS).