NPR logo

Stitch In Time: Fixing A Heart Defect Before Birth

  • Download
  • <iframe src="https://www.npr.org/player/embed/131968225/132019840" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
  • Transcript
Stitch In Time: Fixing A Heart Defect Before Birth

Health

Stitch In Time: Fixing A Heart Defect Before Birth

Stitch In Time: Fixing A Heart Defect Before Birth

  • Download
  • <iframe src="https://www.npr.org/player/embed/131968225/132019840" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
  • Transcript

Kim Wells was 23 weeks pregnant when doctors told her there was a problem with her unborn daughter's heart. Two days later, the Iowa woman found herself in a Boston operating room, surrounded by doctors.

"They told me that they would go directly through my stomach with a needle into my uterine wall, directly into her heart," Wells says.

Wells is one of 200 or so women who have undergone an incredibly delicate operation that can actually prevent their babies from being born with a fatal heart defect called hypoplastic left heart syndrome, or HLHS.

Without this operation, these babies are born with half a heart. But if it works, fetal surgery enables them to develop almost normally.

Avoiding A Devastating Condition

About 17,000 U.S. babies are born every year with a serious heart defect. Nobody knows how many might benefit from the kind of fetal surgery Wells had.

But few are as lucky as she and her daughter. Either their heart problems go undiscovered, or they're diagnosed too late, or the diagnosing physician isn't aware that doctors in a few centers are doing fetal surgery to prevent HLHS.

The root cause of HLHS, much of the time, is a partially blocked valve that regulates blood flow from the heart's main pumping chamber, the left ventricle, to the aorta, which carries blood to the entire body.

Article continues after sponsorship

When the aortic valve doesn't open fully, the fetus's left ventricle gets exhausted from pumping against the pressure of the stuck valve. Over crucial weeks of prenatal heart development, the left ventricle shrivels (that's what "hypoplastic" means) and becomes useless.

The defect is fatal unless surgeons do a heroic re-plumbing operation that allows the weaker right ventricle, which normally pumps blood to the lungs, to serve the whole body. Even when it's successful, patients live a limited life.

Precision Surgery

The goal of fetal heart surgery is "to open the aortic valve at a point when the left ventricle is not quite beyond irreparable damage," says Dr. Wayne Tworetzky, a cardiologist at Children's Hospital in Boston.

Doing that requires considerable skill. In Kim Wells' case, Dr. Louise Wilkins-Haug, a specialist in maternal-fetal medicine, pushed a long needle through Wells' swollen belly, through the muscle of her uterine wall, and into the beating heart of the fetus within.

At 23 weeks, that heart was only three-quarters of an inch long. "It's about the size of a grape," Tworetzky says.

The real target — the faulty aortic valve — was even tinier, "probably the size of the tip of a ballpoint pen," he says.

Once the needle was aimed precisely at the teensy valve, another doctor, cardiologist Audrey Marshall, pushed a guide wire through the needle. A miniature balloon slipped over the wire.

The aim was to thread that wire, and then the balloon, through the blocked aortic valve, then inflate the balloon — gently dilating the stuck valve.

'Golf Ball In A Snowstorm'

It wasn't easy. For one thing, it's hard to maneuver the balloon into the right place. In Wells' case, it took several tries. First it went into the wrong valve, then the wire bumped into the interior wall of the fetus's heart and curled over.

Even with state-of-the-art ultrasound images displayed on a big screen, it's hard for the doctors to see exactly where the balloon is. "It's like trying to find a golf ball in a snowstorm," Tworetzky says. His job is to help interpret the ultrasound image for the other doctors.

Then there's the time factor. "We really have to get this done within seconds or at most several minutes from when the needle is first placed inside the [fetal] heart," Tworetzky says.

Otherwise, the fetus's heart may slow down, a condition called bradycardia. And in fact, as the team was inflating the fetal valve in Kim Wells' case, the tiny heart did slow down.

"If the heart slows down or even stops, there's a chance we may lose the fetus," Tworetzky says.

In Wells' case, he detected another ominous sign — fluid around the heart.

"We are sticking a needle into the heart, and not surprisingly, there can be bleeding," he explains. "That can compress the heart." And that too can be fatal.

So Dr. James Lock made the decision to stop the operation. As chief of cardiology at Children's Hospital, he is sort of the leader of the orchestra.

"Bring everything out of the body, everything out of the body," Lock called out. Quickly, the others pulled out the guide wire, the balloon and the long needle.

The team thought they had successfully opened up this fetus's stuck valve. But at that point, nobody could be sure whether the operation was a success.

Few So Fortunate

As Kim Wells' pregnancy continued, ultrasound scans showed things were looking good. And when she had her baby 15 weeks later, the newborn's heart had developed normally.

Now that little girl, Hannah, is a lively, inquisitive 4-year-old. "She runs circles around our oldest daughter, who is completely healthy," Kim Wells laughs. "Yeah, she's a real ball of energy."

Hannah did require two heart procedures — one as a newborn to dilate her aortic valve a little more, and another open-heart operation at age 3 to repair a tear in one of the valve's three leaflets. And she'll probably need some more down the road.

But her father, John Wells, says that's nothing. "She has four chambers of her heart that are functioning," he says. "So that is the success story of the fetal intervention."

But few are as fortunate as Hannah Wells. At least half the time, serious heart defects — a broad category that includes aortic valve problems but many other disorders — aren't detected during pregnancy, Tworetzky says.

He says more parents should ask their obstetricians or ultrasound technicians to take a close look at the developing fetal heart to make sure there are four pumping chambers, and four valves. "They shouldn't be shy to ask their doctor, 'Did you see this?' " Tworetzky says. Because sometimes, at birth or even before, something can be done about it.