Health & Medicine

Why fixing a common defect in preemies no longer requires cutting open tiny chests

UC Davis doctors repair leaky artery in preemie child

Doctors at UC Davis repair a leaky artery common to preemie babies with a non-surgical option using nano technology.
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Doctors at UC Davis repair a leaky artery common to preemie babies with a non-surgical option using nano technology.

Weighing little more than 3 pounds 7 ounces, tiny Marcellus Brown had a life-threatening problem with his blood flow, one that is common for preemies. To fix it, surgeons at most medical centers cut into these infants’ delicate chests and spread them open to work.

Dr. Frank Ing made just a needle prick to perform a procedure that repaired the problem.

“It is only in the last year or two where we were able to find a device that was small enough to get through the small vessels of the smallest babies, like (baby Marcellus’) size, and get to the heart and do this safely,” said Ing, a pioneering pediatric cardiologist at UC Davis Medical Center. “The technology of being able to miniaturize or nano-size the tools we use to get into the smaller vessels in the smaller hearts … is new.”

Marcellus spent just 24 weeks and six days in his mother’s womb, while most pregnancies last 37 to 40 weeks. When he was born, his development was at such an early stage that his body still depended on his mother for oxygen.

His lungs weren’t yet working, Ing said, explaining that fetuses have a blood vessel called the ductus arteriosus that diverts already-oxygenated blood around the lungs and into their bodies. Just before fetuses are born, he said, that blood vessel typically closes up, and the blood starts moving through their lungs.

Occasionally, even full-term babies are born before this blood vessel has closed, a condition known as patent ductus arteriosus, or PDA, Ing said, but it’s most common among premature infants and can be life-threatening.

“Imagine if you had a newspaper delivery business, and you have 100 kids. Every morning you put newspapers into the basket and you say, ‘OK, go deliver to the community,’” Ing said. “If you have some kids who are delinquent, who take the newspapers and just ride around the community and don’t deliver the newspapers, even if they come back to your warehouse, you can’t add any more newspapers to their baskets for delivery. Their basket is already full.”

If you get enough kids doing this, Ing said, few newspapers are delivered and the business dies. In this case, the newspapers are the oxygen, and the warehouse is the lungs. Oxygen-rich blood keeps flowing back to the lungs rather than to the body, Ing said, and the lungs fill with so much blood that the preemies can’t breathe very well.

Sometimes, neonatologists can use medications that encourage the blood vessel to close on its own, Ing said, but more often than not, surgery is done.

The idea of surgery was pretty scary for Marcellus’ mom, 27-year-old Alexandria Brown. Her son had been born at another regional hospital, and his condition had gone downhill after his birth. He started out breathing on his own, Brown said, but that all changed after he got an infection.

“At 5 o’clock in the morning, they’re calling me telling me that Marcellus pretty much stopped breathing on his own,” Brown said, “and he’s got a really bad infection. They gave me the option to transfer him to UC Davis and I took it.”

Brown said she loved being at UC Davis because they listened to her concerns and addressed them. It was at UCD that Brown learned that her son also would need treatment to close his ductus arteriosus, she said, and she was relieved that they presented a nonsurgical option.

Marcellus was still on a ventilator, she said, and fragile at that time, so she feared that cutting through the muscles in his chest and the resulting scar tissue would make it even harder for him to regain the ability to breathe on his own.

Over the last few years, Ing said, nano-sized tools have been developed that cardiologists like him use to treat preemies even half the size of Marcellus. They use the same catheterization technique as the one used to clear blockages from adult arteries.

Ing said he tunnels the catheter and ultra-thin wires through the femoral vein in the groin, then to the inferior vena cava into the right atrium, into the right ventricle, into the pulmonary arteries and then through the aorta to the ductus arteriosus. He places tiny plugs in the opening to close it up.

A preemie’s size and precarious health condition, however, add many more variables to this procedure, Ing said.

“It doesn’t take much for them to lose temperature or lose glucose,” he said. “Dealing with kids this size takes teamwork. It’s not just me doing this.”

In addition to the pediatric cardiologist, the team is composed of a neonatologist, an anesthesiologist, a catheter lab technician, the preemie’s bedside nurse, a pharmacist and sometimes a nurse practitioner or fellow. It’s not possible, Ing said, for one person to go off alone and perform this procedure.

“You have to have a team where you have expertise in managing babies this size. That’s the neonatologist,” he said. “Then you have to have somebody who’s a pediatric anesthesiologist who understands the physiology and knows how to give the ventilation and anesthesia for babies this size.”

The bedside nurse has been with that preemie regularly and knows nuances critical to the patient — how often mucous has to be suctioned, for instance. The pharmacist is present because the types of medicines and their dosages are different for an infant this size. Technicians place the equipment where everyone can see it, and they ensure that the bassinet remains at a temperature that will sustain the preemie’s life.

Over the years, Ing said, he’s developed a checklist that he follows to the letter. Once, he said, a battery that powered a warmer on a bassinet wasn’t charged well, and over the five minutes it took to transport the infant to the lab, he experienced a big drop in temperature.

Even fluids used to flush out veins must be kept at body temperature, Ing said, and they have to tightly control how much fluid is injected because even a teaspoon of it is a lot in babies as small as Marcellus was at the time of his surgery.

For these procedures, he said, you’ll see eight people pushing a bassinet with a 2-pound baby in it. There’s an oxygen tank and IV pole, Ing said, and everyone is moving pretty slowly because there’s a lot to monitor.

Most medical centers are not yet doing this procedure, Ing said, because they have not acquired the equipment to do so or don’t have a cardiologist and team trained in performing it.

“I always say the advance of medicine, with everything being equal, goes from more invasive to less invasive,” Ing said. “That makes sense. In the old days, when you had to get a shot for penicillin, those needles were huge. They’re much smaller now. So, again, that’s less invasive because it’s a smaller system.”

Brown said that she would recommend the procedure to any parent who has a preemie.

“As soon as Marcellus got that procedure, he actually took out the breathing tube himself and was breathing on his own,” Brown said. “I think he did that within five hours of the procedure. He was breathing on his own, and he gained weight almost immediately. He was a whole different baby.”

Marcellus is now 10 months old, and Ing said the healthy-looking baby boy looks nothing like the preemie on whom he operated. Brown said her son is developmentally performing at the age of a 4- or 5-month-old but that doctors have told her he will likely catch up to his peer group by the time he turns 2.

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