Children born with specific heart defects often need multiple invasive surgeries during their early years. The first surgery typically involves placing a device known as a shunt to facilitate better blood circulation. However, as these children develop, the shunt often requires replacement to suit their growing bodies. Researchers have now created a revolutionary shunt that expands when triggered by light. This innovative device could potentially diminish the number of surgeries needed, involving opening the chest.
Children who are born with heart defects affecting the lower chambers of the heart typically face a series of invasive procedures in their early life. Initially, a plastic tube named a shunt is implanted to enhance blood flow. However, as they grow, these children frequently need the shunt replaced to fit their changing anatomy. Researchers are now introducing a shunt that can expand when activated by light. If successful, this new device could significantly lower the frequency of open-chest surgeries required for these children.
The findings will be shared at the upcoming fall meeting of the American Chemical Society (ACS).
According to Christopher Rodell, who is presenting this research, “After surgeons first place the tube, these children often require an additional two, three, or even four surgeries just to implant slightly larger tubes. Our aim is to expand the shunt from the inside using a light-emitting catheter inserted within it, completely eliminating the need for further surgeries.” Rodell serves as an assistant professor of biomedical engineering at Drexel University.
Congenital heart defects impact the heart’s ventricles, leading to reduced blood flow to the lungs and other body areas. Without surgical intervention, infants with these conditions cannot survive. Oftentimes, these babies are born small but can grow rapidly after their initial shunt surgery. To keep up with their growth, additional open-chest surgeries are frequently necessary. Each surgical intervention carries inherent risks. In a study involving 360 patients who underwent the initial heart reconstruction, 41 required further surgeries for a larger shunt, and seven patients lost their lives as a result.
Previously, Rodell’s colleagues at Drexel, Amy Throckmorton and Kara Spiller, developed an expandable prototype intending to replace the most common type of shunt. They achieved this by lining the inner surface of the tube with a hydrogel made from polymers interconnected by bonds known as crosslinks. When new crosslinks form, water is expelled from the hydrogel, pulling the polymers together, resulting in the contraction of the hydrogel and an increase in the shunt’s inner diameter. The initial prototype initiated crosslink formation automatically, without any external activation.
Rodell collaborated with Throckmorton and Spiller to refine the shunt, ensuring that the construction materials were safe for clinical applications and could be tailored to suit the individual needs of children. He created new polymers for a hydrogel that would form new crosslinks following a specific trigger. For triggering crosslinking on demand, Rodell opted for blue light since it provides the necessary energy for the reaction while being safe for living tissue.
“Light has always been a favorite trigger of mine because it allows you to control when and where it is used,” Rodell notes.
For the updated device, Rodell, alongside graduate student Akari Seiner, is utilizing a fiber-optic catheter—essentially a long, slender tube with a light-emitting end. To activate the light-sensitive hydrogel inside the shunt, the plan is for surgeons to insert the catheter into an artery near the armpit and guide it into position, thereby avoiding the need to open the child’s chest.
In laboratory tests, the researchers discovered they could expand the shunt in controlled increments. The amount of expansion varied depending on how long the device was exposed to light—indicating that adjustments can be made individually for each child after implantation. They were able to increase the shunt’s size up to 40%, broadening its diameter from 3.5 millimeters to 5 millimeters—almost matching the size of the largest shunts used in young patients. They also investigated the impact on blood cells and vessels and found no signs of blood clots, inflammatory reactions, or other adverse health effects from the implanted tube.
The next step for the team is to test full-length shunt prototypes in a simulated environment mimicking the human circulatory system. If these tests yield positive results, they will progress to experiments involving animal models. According to Rodell, this technology could serve purposes beyond treating single-ventricle heart disorders. Surgeons could also employ similar tubes for reconstructing blood vessels in children who sustain injuries, such as in car accidents.
“These medical procedures face similar challenges: children are not just little adults; they continue to grow,” Rodell explains. “It’s essential to consider how these grafts will perform over time in terms of biomaterials.”
This research received funding from The Hartwell Foundation.
