Researchers are developing a blood shunt designed to grow with children, potentially reducing the need for repeated high-risk open-chest procedures.
The shunt features an inner diameter that expands when exposed to a blue light-emitting catheter, offering a less invasive solution for children born with congenital heart defects.
Children with defects in the heart’s lower chambers often undergo a series of complex surgeries early in life, starting with the implantation of a shunt to improve blood flow.
However, as these children grow, their shunts frequently need to be replaced with additional operations.
The new shunt technology could drastically change this scenario by allowing the shunt to expand in size as the child grows, reducing the number of interventions required.
The research was spearheaded by Christopher Rodell, an assistant professor of biomedical engineering at Drexel University.
He said: ‘After the surgeon first puts in the tube, these children often have to go through an additional two or three, maybe even four, surgeries just to implant a slightly larger tube. Our goal is to expand the inside of the tube with a light-emitting catheter that we insert inside the shunt, eliminating the need for additional surgeries.’
Congenital heart defects affecting the ventricles restrict blood flow to the lungs and other vital organs, and without surgical intervention, these conditions can be fatal.
Babies with these disorders often undergo an initial shunt implantation, but rapid growth necessitates further procedures to replace the shunt.
These repeated operations pose significant risks, including a heightened chance of complications and even mortality. In one study of 360 patients who underwent initial heart reconstruction, 41 required additional surgeries to replace their shunt, with seven of these cases resulting in death.
Christopher Rodell’s collaboration with colleagues Amy Throckmorton and Kara Spiller at Drexel University led to the development of an expandable shunt prototype.
This prototype uses a hydrogel-coated interior that contracts upon exposure to water, increasing the shunt's inner diameter. The earlier design expanded automatically, but Rodell improved it by introducing polymers that form new crosslinks when exposed to blue light, allowing for controlled, on-demand expansion.
‘Light has always been one of my favourite triggers because you can control when and where you apply it,’ Rodell explained.
In laboratory experiments, Rodell and his team, led by graduate student Akari Seiner, demonstrated that the shunt could be expanded incrementally by adjusting the duration of light exposure.
The shunt’s diameter increased by as much as 40%, from 3.5-5mm, nearly matching the size of the largest shunt typically implanted in children.
Notably, the modified shunt showed no signs of causing blood clots, inflammation, or other adverse reactions in their tests.
The following research phase will involve testing full-length shunt prototypes in a system that mimics human blood circulation. The team plans to proceed with animal trials if these tests prove successful.
This technology holds promise beyond single-ventricle heart defects, with potential applications in other paediatric surgeries where growth must be accounted for, such as in cases of traumatic injury.
Rodell said: ‘In these procedures, you run into the same problem: Children aren’t just tiny adults; they continue to grow. That’s something we need to account for in biomaterials – how that graft will behave over time.’
The research was funded by The Hartwell Foundation.
