Masen Slabaugh smiles big as he lies on a colorful blanket.Every day, Karlie Slabaugh looks at her baby, Masen, and thinks, “Wow, I can’t believe he’s healthy.”

Masen, now 5 months old, would likely have been stillborn if not for the discovery and successful treatment of a heart problem while he was in utero.

Slabaugh says the routine ultrasound she had 20 weeks into her pregnancy ultimately saved Masen’s life. This is when his racing heart rate—a potentially fatal arrhythmia known as fetal supraventricular tachycardia, or fetal SVT—was detected.

At 20 weeks of gestation the average fetal heart rate is 140 beats per minute. Masen’s was in the 240s to 250s. This raised a red flag that sent Slabaugh to the specialists at Spectrum Health Medical Group’s maternal-fetal medicine office for testing.

When doctors there found that the heart arrhythmia had caused a buildup of fluid in Masen’s developing body called fetal hydrops, “they thought they’d have to deliver him that day,” Slabaugh said.

The next step was critical: The maternal-fetal medicine team called in Jeffrey Schneider, MD, a pediatric cardiologist in the congenital heart center at Spectrum Health Helen DeVos Children’s Hospital.

A rare specialty

Dr. Schneider specializes in the prenatal diagnosis of congenital heart disease. In addition to heart rhythm problems like Masen’s, Dr. Schneider provides prenatal diagnosis of other heart problems, such as structural heart defects and infections of the heart.

Dr. Schneider was determined to get Masen’s heart rate under control in the womb by treating his mother with anti-arrhythmic medication. When Masen’s tachycardia didn’t respond to the first drug, Dr. Schneider tried a series of four medications, individually and in combination, before hitting on a successful pairing.

It was a harrowing process for the family, with Slabaugh spending about 30 days in the hospital, on and off, over the course of three months.

“We could see on the ultrasound that he was very swollen with fluid,” Dr. Schneider said. “That’s what makes Masen’s case one of the most rewarding for me personally—I know he wouldn’t have survived without treatment.”

Masen Slabaugh giggles as he sits in a 'monkey' chair.Masen’s tachycardia was unusually stubborn, but when the drugs finally took hold, the tachycardia converted to a normal rhythm, and the swelling gradually decreased.

“We’re very passionate about telling this story because the work of the maternal-fetal medicine team and Dr. Schneider’s practice; they were fantastic,” Slabaugh said. “They were very realistic throughout the whole process and there were no empty promises, but they were supportive and dedicated, and we felt like we were all a team.”

Although her pregnancy was in jeopardy a couple of times along the way, Slabaugh said Dr. Schneider and his colleague, Christopher Ratnasamy, MD, a pediatric electrophysiologist, “were adamant that delivery could wait, and they finally found a good regimen of medications and that took him all the way to 37 weeks.”

Masen was born small but healthy in October 2014. He came home after spending just three weeks in the neonatal intensive care unit at Helen DeVos Children’s Hospital. The doctors’ fears that he would have lung or liver failure were not realized, and they now expect him to be off the anti-arrhythmic medications well before he’s school age.

Meeting Masen was a victory for both the family and the medical team.

“After looking at the ultrasound images for so long, getting to meet him for the first time was really exciting,” Dr. Schneider said. “This baby is so beautiful.”

And although he’s still tiny, Masen is on track developmentally and meeting all his milestones.

Hope for other families

For parents who may find themselves in a similar situation, Slabaugh offers sage advice: Trust that the doctors are on your side. Establish a working relationship with them. Be very involved in your child’s care. Ask lots of questions and listen to the answers.

And don’t put too much stock in what you find online: “Everything we had read said that he was not going to survive. But our doctors were adamant that there’s a process here and we’re going to follow it.

“When you’re sitting there, you’re hopeless, but those doctors—they want to do everything they can to make sure that your child gets the chance they deserve. We’re very lucky.”

Not all prenatal heart problems can be treated in the womb like Masen’s.

“With modern surgery we can help most babies with structural heart defects after they’re born,” Dr. Schneider said, “but in utero surgery is still the next frontier.”

Yet there’s great value in prenatal diagnosis because of the planning that can be done for the baby’s birth, said Dr. Schneider, who coordinates with perinatologists, neonatologists and pediatric heart surgeons to ensure proper preparation.