Every year, over a million children worldwide are born with congenital heart defects that threaten their lives and development. It’s estimated that in the US alone, at least 1 million children are living with a congenital heart defect. While treatments are often available for older children and adults, infants and toddlers pose a unique challenge: their small size and ongoing growth make it difficult to implant devices that can adapt to their developing bodies.
This leaves the youngest patients vulnerable to heart damage or even failure. It’s like a race against time, hoping they grow enough for treatments before something really bad happens.
“There are some products that are clinically available, but they are not indicated for children until they’re at least 20 kilograms, or about 44 pounds,” says Nnaoma Agwu, a fourth-year Ph.D. candidate at UC Irvine. “So, there’s a gap between toddler age and when children reach a certain weight, making them eligible for the currently available treatments. Unfortunately, the leaky valve during that time can result in devastating right ventricular heart dysfunction or dilation.”
Agwu and his mentor Professor Arash Kheradvar have developed a new valve that can also work for toddlers. The origami-inspired valve operates at different diameters, which makes it suitable for growing toddlers.
The Iris Valve
Congenital heart defects (CHDs) are the most common type of birth defect, affecting about 1 in every 100 newborns worldwide. These defects occur when a baby’s heart doesn’t develop properly in the womb. For many, these issues impact the right ventricular outflow tract (RVOT), a pathway that helps blood flow from the heart to the lungs. In many of these heart problems, the pathway between the heart and the lungs becomes narrowed or blocked.
The Iris Valve attempts to solve that problem.
First of all, the valve can be folded to around 4 millimeters and implanted without open-heart surgery. It is essentially sent through the femoral vein in the thigh. Kheradvar says that when closed, the Iris Valve looks like the Mercedes-Benz three-pointed star logo.
Then, once implanted, the valve can expand from 12 millimeters to 20 millimeters in diameter. This flexibility allows the valve to accommodate a child’s natural growth, eliminating the need for multiple invasive surgeries to replace outgrown valves. This size adaptability is what makes all the difference.
“It’s crucial for the valve to be competent, meaning that when it’s closed, it should stay closed without any leakage,” he says. “In a typical transcatheter trileaflet heart valve, such as those commercially available, there is only one specific size where the valve resembles the Mercedes-Benz logo, indicating competency and no leakage. If you apply pressure circumferentially to the valve stent, the three-pointed star will twist — what we call ‘pinwheeling’ — and if you expand it radially, it will leak.”
Animal testing went well
The idea came about in 2020, when Agwu and Kheradvar started working with Dr. Michael Recto, an internationally recognized interventional pediatric cardiologist at Children’s Hospital of Orange County. The complementary expertise first led to a sketch concept and then developed into a functional heart valve project.
To ensure the Iris Valve’s safety and effectiveness, the research team conducted preclinical trials using Yucatan mini-pigs. These animals, which grow rapidly, provided an ideal model for testing how the valve would adapt to a growing child’s heart.
The results were promising. Over a six-month period, the valves remained precisely in place with minimal or no regurgitation (leakage). Even as the animals’ hearts grew, the valves expanded smoothly and maintained their function. The team observed a mild inflammatory response, which is typical for implanted devices and a sign that the body was adapting to the new valve. But, overall, there seemed to be no issues with the valve.
The results were recently published and presented at leading conferences such as the American Heart Association Scientific Sessions.
“Nobody has taken this approach, to the best of our knowledge,” Kheradvar says, adding that the next step is to extend animal studies and proceeding with the Food and Drug Administration approval process for the first in-human implant.
“The IRIS valve has been designed according to origami concepts such that its three leaflets would retain a fully-coapted form as it is expanded to a larger size,” a recent study describing the results notes.
“Using the delivery catheter, the smallest delivery profile reported, we successfully implanted the IRIS valve within the pulmonary annulus of mini pigs with encouraging results.”
New hope for thousands of families
It’s unclear when or if the valve will become available for human use. Clinical trials can take years. And there is no guarantee of success in humans, even though the results look promising now.
Still, for children with congenital heart defects, the Iris Valve represents hope. It addresses a critical unmet need, offering a solution for the youngest patients who previously faced limited options.
As the Iris Valve moves closer to real-world use, thousands of families may soon find relief. Their children may have a safer, more adaptable option for managing their heart conditions. In the world of pediatric cardiology, this tiny valve could make a huge impact.
