A Children's Hospital Los Angeles team has become the first in the world to implant a cardiac stent that's designed specifically for babies and young children and can be expanded all the way to adult size.

The first-in-human procedure, which took place Feb. 1 in the Cardiac Catheterization Lab, is part of a multicenter early feasibility study led by Children's Hospital Los Angeles. The study aims to solve a longstanding limitation of traditional cardiac stents: They're too large to be used in the youngest and smallest patients.

"We know that stents can work really well for patients with congenital heart disease. But we've been lacking appropriate stent technology for neonates, infants and young children," says Darren Berman, MD, Director of Congenital Interventional Catheterization and the national principal investigator for the study. "This expandable stent opens the door to a whole new treatment option for these children. It has the potential to make an enormous impact."

A better option

The stent's first recipient was a 5-month-old boy named Asher who was born with two complex congenital heart defects: dextro-transposition of the great arteries (D-TGA)-;a condition where the two main arteries carrying blood out of the heart are switched in position-;and coarctation (narrowing) of the aorta, which carries blood flow to the body.

Soon after birth, Asher had surgery at Children's Hospital Los Angeles to repair those defects, but the narrowing in his aorta recurred. In November, the team performed a minimally invasive procedure in the Cardiac Catheterization Lab, using a balloon to try to open the artery. But again, the fix did not last long.

"Balloon angioplasty is successful in a certain percentage of children. But it's generally not as successful as implanting a stent, which acts as a metal scaffold that can more reliably keep the artery open," Dr. Berman explains.

Normally, the next step would have been to try the balloon procedure again or do open-heart surgery. Asher had already had a tough recovery from his first surgery. "It was a long, hard process for him," says his mom, Hilla. "We didn't want him to have to go through that again."

The investigational expandable stent offered an appealing option. The stent is designed for neonates, infants and young children who have blockages or narrowing in the aorta or pulmonary artery.

"Right off the bat, we were excited," Hilla says. "But when we learned that Asher would be the first human [to receive it], that set us back a bit. We were scared. But after weighing the pros and cons, we decided to try the stent. It was minimally invasive and less pain and a shorter recovery for Asher. That's what we were looking for."

Miniaturized technology

The pioneering procedure was performed by Dr. Berman and Patrick Sullivan, MD, the site principal investigator for the study. The team inserted a catheter-;a thin, flexible tube-;into an artery in the baby's leg. Guided by an X-ray monitor, they then carefully threaded it through the artery and across the area of narrowing.

The physicians used a stent made by Renata Medical that comes premounted and crimped onto a balloon inside the delivery catheter. The company's engineers worked to miniaturize this technology to accommodate the cardiac needs in pediatric patients. When the catheter reached the narrowed aorta, the team inflated the balloon, expanding the stent across the area to prop open the artery. The balloon was then deflated and removed, along with the catheter, while the stent remained securely in place.

"One of the most remarkable aspects of this new stent and delivery system is its size," Dr. Berman says. "The delivery system is about the size of a piece of spaghetti. Currently available adult-sized stents require much larger-sized catheters that can't be safely used in neonates and infants. The miniaturization of this technology is really groundbreaking."

The other key innovation is that the stent can be expanded to fit a child's growing blood vessels. As the child grows, the team can expand the stent all the way up to adult sizes-;more than 18 millimeters wide. Dr. Berman anticipates that patients who receive the stent as babies will likely need to have it expanded two to four times over their life. The adjustments will be done through minimally invasive catheter procedures.

"It's designed to essentially last a lifetime," he says.

Home the next day

In addition to Children's Hospital Los Angeles, the study is taking place at three other centers around the country. The goal is to enroll a total of 10 patients across the four sites over the next few months.

The Food and Drug Administration will then review the safety and efficacy data from those first 10 patients. If results are positive, the next step will be a larger trial involving more patients and centers.

Meanwhile, the first procedure was a success, and Asher went home the next day-;quickly returning to his normal, happy, smiley self. "He's doing amazing," Hilla says. "It is such a relief. Every day now I wake up happy. We are so grateful and appreciative that we were offered this option."

Dr. Berman stresses that bringing breakthrough technology to patients at Children's Hospital Los Angeles is a team effort across the entire Heart Institute, led by Co-Directors Vaughn Starnes, MD, and Paul Kantor, MBBCh, MSc, FRCPC. That effort also involves the entire Cardiac Catheterization Lab team-;including interventional cardiologists, cardiovascular technicians, cardiac nurses and dedicated cardiac anesthesiologists.

"This was a momentous procedure and a tremendous collaboration," Dr. Berman says. "We're very excited to be leading this study and to help advance new technology for the youngest children with complex heart defects."