For babies born with a certain heart defect, implantation of a “shunt” is essential to their survival. A new type of shunt can be expanded using light, which could eliminate the need for further heart surgery currently needed to replace larger shunts as the baby grows.
Hypoplastic left heart syndrome is a condition in which the left side of the heart is severely underdeveloped and unable to support blood circulation throughout the body. If left untreated, a baby born with this defect will not survive.
One of the key steps related to This treatment involves connecting the aorta to the main pulmonary artery to allow blood flow from the right side of the heart to the lungs. This connection is made by performing open-heart surgery to insert a polymer tube known as a shunt.
Unfortunately, as the baby grows, it requires successively larger shunts to accommodate the increasing blood volume. This means that up to four consecutive surgeries may be needed to replace these shunts, each surgery posing a risk and placing physical stress on the baby.
That's where the experimental new shunt comes in. Developed by Assistant Professor Christopher Rodell of Drexel University in Philadelphia and his colleagues, the shunt's inner walls are coated with a hydrogel, which consists of polymer molecules surrounded by water.
Under normal conditions, this gel remains constant in thickness. But when exposed to blue light, the polymer molecules cross-link with each other and pull together, squeezing out water.
As a result, the inner wall contracts and becomes thinner, increasing the inner diameter of the shunt – the longer the light exposure, the greater the contraction. This allows a greater volume of blood to pass through the existing shunt, meaning Negative needs to be replaced.
Blue light could theoretically be administered through a thin fiber-optic cable surgically inserted into an artery near the armpit, eliminating the need for open-heart surgery.
In laboratory tests so far, the scientists have been able to gradually expand one of the shunts by up to 40%, increasing its inner diameter from 3.5 millimeters to 5 millimeters. The latter figure is close to the size of the largest shunts currently used in infants. Tests are currently planned on a mock-up of the human circulatory system, with animal tests likely to follow.
“Children are not just tiny adults; they are continuing to grow,” Rodell says. “One thing we have to take into account with biomaterials is how that graft is going to behave over time.”
Other groups appear to have this reality in mind, including scientists at Boston Children's Hospital and the University of Minnesota who are developing replacement hearts. valves It can be enlarged as the baby grows.
A paper on the Drexel study, led by graduate student Akari Seiner, will be presented at the fall meeting of the American Chemical Society.
Source: American Chemical Society