Former NICU neighbors overcome rare heart disease to become college roommates

Two neonatal intensive care unit patients who were once given a 40% chance of survival are now thriving years later.

Tate Lewis and Seth Rippentrop were born weeks apart in 2002. They were diagnosed in utero with hypoplastic heart syndrome, a congenital condition where the left side of the heart doesn't form properly, and treated at Children's Health.

Dr. Steve Leonard, a pediatric cardiothoracic surgeon at Children's Health, who treated Tate Lewis, said the diagnosis can be deadly if not treated immediately.

"It's a defect that is uniformly fatal if it's not taken care of within the first few days of life," Leonard told "Good Morning America."

Cheri Lewis, Tate's mother, recalled the moment she first heard about her son's diagnosis.

"We were terrified when we found out about Tate's diagnosis," she told "GMA."

Seth Rippentrop's mother, Kimberly Rippentrop, said she also remembers that moment over two decades ago.

"I would pray, just asking God to let him come home and sleep one night," she said.

The boys would need multiple surgeries and extensive treatment for their condition, which requires the reconstruction of the right side of the heart so it can do the job of a typical heart.

Their mothers met in the hospital NICU with their sons in side-by-side rooms.

Seth Rippentrop had to have three major surgeries and Tate Lewis, who also had a stroke that paralyzed one of his vocal chords, needed to have five surgeries.

Despite the odds, both boys survived and built a close bond together.

"I was just always very aware of the fact that I had half of a heart as a kid and I just always knew that there was something different," Seth Rippentrop said.

"What we've been through in the past, I feel like, gives us hope," he continued.

Today, the two close friends are both juniors in college and roommates at the University of Texas at Dallas, where Seth Rippentrop is a dean's list student and Tate Lewis is a member of the men's golf team.

Although they may have lifelong complications, both Seth Rippentrop and Tate Lewis say they feel positive about their future and know to never take life for granted.

"This was something we were born with and so we have to treat it with care but also we have to live life as well and set goals," Tate Lewis said.

Said Seth Rippentrop, "We've already defied so many odds and we've already gone against so many expectations of what our life was going to be like so it makes me really hopeful for the future."

Leonard added separately, "That's the most rewarding aspect of what we do is to see these patients reach adulthood and to be able to fulfill their dreams."