Flow restrictors, like the one pictured, are showing promise for helping patients with hypoplastic left heart syndrome.
Babies born with hypoplastic left heart syndrome, in which the left side of the heart doesn’t fully develop and thus can’t pump blood very well, typically require open-heart surgery soon after birth or a hybrid surgical approach combining stenting and open surgery to establish systemic blood flow and control pulmonary blood flow. Given the already fragile state of the infant, however, neither approach is optimal, and both have high mortality rates.
Doctors at Children’s of Alabama are helping these children by using an internal pulmonary flow restrictor created by modifying a microvascular plug. They form the device by cutting a tiny hole in the Gore-Tex covering of the microvascular plug originally designed to close blood vessels in children and adults. With this use of this device, they are able to postpone surgery for months until the infant is bigger and stronger while still controlling pulmonary blood flow in a completely non-invasive manner.
“The problem we’re addressing is over-circulation of blood to the lungs,” explained pediatric cardiologist Mark Law, M.D. “Traditionally, it requires open-heart surgery to place a band around the pulmonary artery to reduce blood flow. However, this surgery is invasive and can be very stressful for the baby.”
Now, Law and his team are able to treat the infant in the cath lab rather than an operating room. There, they thread the plug through the femoral or internal jugular vein into the pulmonary artery to partially restrict excessive blood flow to the lungs. “It’s a far less invasive procedure and the recovery is faster,” he said. It also allows the surgeons to operate without scar tissue from a previous surgical procedure.
This procedure enables babies who are too fragile for surgery to safely grow stronger before undergoing their first operation. In one study, 10 out of 13 infants treated with this technique survived to their next surgery, typically performed within two to six months of the catheter procedure. When compared to historical data from similar high-risk patients who underwent traditional procedures, the new technique was associated with significantly better six-month survival rates after adjusting for other risk factors.[1]
Importantly, the baby’s pulmonary arteries grow over that time, which is crucial for their long-term outcomes. In addition, the devices can be easily removed during subsequent surgical procedures.
Law and his team have presented a series of five cases in which they used the technique on babies who were too medically fragile for surgery. All survived and all were later able to undergo the needed open surgery. “We’re confident some of these babies wouldn’t have made it otherwise,” he said. “But because they’re older, bigger, stronger, and breathing on their own,” the procedure was much less risky.
Still, challenges remain. The device must be customized for each patient, and its small size limits its use to very young infants.
Nonetheless, pediatric cardiologists across the country are adopting the procedure, Law said. “We’re all learning from each other and sharing data to refine the technique.”
“This technique represents a shift in how we think about treating congenital heart defects,” Law said. “The ability to delay surgery and avoid scar tissue is a game changer.”
[1] Sperotto F, et al. Circ Cardiovasc Interv. 2023;16:e013383. DOI: 10.1161/CIRCINTERVENTIONS.123.013383
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