A pea-sized device used to seal tiny but potentially deadly holes in the hearts of premature infants has been approved by U.S. regulators, making it one of the smallest complex medical devices ever invented and cleared for sale.

Abbott Laboratories’ Amplatzer Piccolo Occluder is one of the first treatments to become available for a common congenital defect that can become dangerous for premature infants. The device can be used in babies weighing as little as two pounds in cases where a hole in the heart used to deliver oxygen-rich blood in the womb doesn’t close after birth.

The Piccolo is threaded into the heart using a catheter that runs through the femoral vein in the thigh. That avoids a taxing surgery for the undersized patients, who are often on ventilators, said Evan Zahn, director of the congenital heart program at Cedars-Sinai Smidt Heart Institute in Los Angeles.

“We’ve never had anything like this, a device from a major medical manufacturer that was specifically designed with these tiny, really at risk, very fragile babies in mind,” said Zahn, the lead investigator of the study that led to the device’s approval by the U.S. Food and Drug Administration Monday. “We’re talking about babies the size of the typical water bottle we all drink out of. They are incredibly frail, fragile and at risk for terrible morbidity and mortality.”

The Piccolo is not expected to be a major sales driver for the Abbott Park, Illinois-based company. Instead, it represents a significant technological advance as medical-device manufacturers work to make their products ever smaller and easier to place in the body without taxing surgeries.

Everyone is born with a small hole in their heart, a condition called patent ductus arteriosus. In the womb, the hole allows a fetus’s blood to bypass the lungs and get oxygenated blood directly from the mother.

Usually, the hole closes a few days after delivery. In some premature newborns, however, it never does, making breathing difficult and leading to a host of potential complications. They include developmental delays, damage to the brain and bowel because they aren’t receiving the blood they need and injuries to the lungs that are flooded with fluid.

For years doctors performed open-heart surgery to close the hole, a procedure now thought to do more harm than good to the smallest patients, Zahn said. Other treatments include medicine to ease the symptoms and encourage closure, though in most cases doctors, patients and families simply wait and hope the hole eventually seals.

“We know it’s there and we know it’s bad, but we have to bite the bullet and hope the kids pull through,” Zahn said of existing medical practice.

The company hasn’t yet announced a price for the Piccolo.