A tumor filled 80% of this 12-day-old baby’s chest. How he survived.

Jayden Mirville-Beamon’s mother watched her 12-day-old baby’s curious eyes scan the hospital hallway last June as nurses took him toward the operating room.

His family sobbed inside the Minneapolis hospital. Jayden’s mother said she believed the baby was communicating to them with those brown eyes, which he had rarely opened.

“I’m gonna be back in a second,” his eyes seemed to say. “Like, it’s not that big of a deal.”

Left untreated, Jayden would’ve died.

A tumor had invaded 80% of the baby’s chest, sticking to his largest artery and shifting his heart to the right, preventing his lungs from inflating properly.

Jayden’s cardiology team at M Health Fairview Masonic Children’s Hospital had prepared using a novel virtual-reality technology that would map the tumor and help surgeons plan their approach in advance.

A weekslong process of grief and guilt was building to a conclusion for parents Somya Mirville and Eddie Beamon. The two had only held Jayden once before the surgery.

“I try not to think the worst or manifest it,” Mirville said in an interview this month. But she couldn’t stop thinking: “What if this is the only time I get to hold him?”

On April 29, Mirville woke up and Jayden wasn’t kicking around in her belly like usual.

She continued on, heading to the mall and then the movies, where she reclined and chowed on Milk Duds, sour Skittles and popcorn to try to get him moving.

“I’m trying to watch a movie and the whole time just thinking, ‘Oh, my God,’” Mirville said. As soon as the film ended, her instincts told her to zoom to the Hennepin County Medical Center, where she works as a patient service coordinator in the pediatric unit.

She spent the night in the hospital, wondering what was wrong with her baby as staff paged cardiologists again and again.

The next morning, a doctor made a diagnosis: Jayden had a rare pericardial teratoma, a type of tumor doctors say randomly occurs. All Mirville saw on the ultrasound image was a super-swollen baby.

Dr. Murfad Peer, a pediatric heart surgeon, said the tumor rapidly increased in size as delivery approached.

Beamon, 24, thought to himself, “How do I even process this?”

Mirville moved to the M Health Fairview hospital to receive care from specialists, but there were no easy answers.

An idea was floated: She could fly to Cincinnati, where doctors handled a similar case. But the staff feared Jayden might not survive the trip.

The doctors also seemed to offer the option of palliative care once the baby was born because the chances he would die were so high that proceeding with painful life saving measures at that point was questionable.

Mirville, 23, was offered the comfort care: stopping treatment to reduce Jayden’s pain. This broke her heart, she said, but she’d approve it if necessary.

She had tried so hard to be healthy during the pregnancy, but she wondered if the complications could be her fault. “I felt guilty,” she said. She canceled the baby shower.

“I also kind of felt grief,” she said, “because I didn’t really know what was going to happen, and seeing everyone kind of freak out and not have seen it before — it was just a lot."

Jayden’s swelling started going down as doctors drained the fluid trapped around his heart through two procedures before he was even born. Hospital staff wanted to take Jayden out right at 32 weeks, Mirville said. The baby got the memo, it seemed.

Mirville’s water broke roughly five days after the 32-week mark.

After just an hour and a half at the M Health Fairview Children’s Hospital, Mirville went in for a C-section. Doctors walked her through every scenario.

Jayden might not breathe. He might immediately need a heart-lung bypass machine to stay alive. He might die while they tried to hook him up to the machine.

Peer came in as backup.

“I didn’t think that the baby would even survive the delivery,“ Peer said, “because the tumor was so huge.”

Instead, Jayden came out crying. That was a good thing, but he still had the tumor.

Mirville didn’t get to hold him. She watched as doctors attached tubes and wires to the 4-pound, 15-ounce newborn.

“My poor baby,” she said.

Mirville wondered what Jayden was feeling: Was he sad? She felt lonely, despite the massive team of doctors buzzing around her trying to figure out what to do. The tumor would soon need to come out.

Dr. Shanti Narasimhan, a pediatric cardiologist at M Health Fairview, said the team included maternal fetal medicine doctors, neonatologists, cardiologists, cardiothoracic surgeons, pediatric surgeons, radiologists and others.

“Nervousness is understatement,” Narasimhan recalls thinking. Removing the massive tumor would require thoughtful coordination, she said.

Ahead of the surgery, Narasimhan tried something she had never attempted: building a virtual-reality model of Jayden’s chest. She used a software program called Elucis, which spliced together CT scans of the baby to produce a digital clone of his anatomy.

On a recent Friday, she demonstrated the technology in an M Health Fairview conference room, strapping on a Meta virtual-reality headset. To an outsider, it looked like she was playing an over-the-top video game. Swinging joysticks around in midair, the doctor could manipulate a virtual bust of Jayden’s organs and tumor hovering in the middle of a dark, 360-degree void.

Peer said the model allowed him to see Jayden’s organs before he ever made an incision. “It’s basically a clone of the patient,” he said.

As a surgeon, Peer said, “You don’t want to be surprised.” The more imaging, the better, he added.

Mirville said she didn’t receive survivability statistics for the tumor removal before Jayden was wheeled into the operating room.

All she knew: The tumor had gobbled up 80% of Jayden’s chest. She sat in the waiting room with Beamon for eight hours.

Inside the OR, a staff of at least 10 watched as Peer cut down the middle of Jayden’s chest. All he could see was tumor. He needed to extend the incision to Jayden’s left side because it was so large, roughly larger than a tennis ball.

The quarter-pound mass was clasped to the baby’s aorta, so they couldn’t move it around without the vital artery stretching taut and lowering his blood pressure. They hooked him up to the heart-lung machine to make it easier to remove the tumor without risking the baby’s life.

Peer, his crew and pediatric tumor surgeon Dr. Bradley Segura carefully made an incision into Jayden’s body to remove the entire tumor and a bit of extra tissue around it in one careful piece. They didn’t chip away at the tumor piece-by-piece to make certain invasive tissue didn’t shed into Jayden’s body and increase the probability of recurrence.

Jayden’s heart quickly shifted back to its correct spot, and he has been tumor-free since the surgery. There’s a slight chance it could come back, as it was an immature tumor.

Peer felt humbled and hopeful. Exceptional teamwork and meticulous planning was key, he said.

Beamon called himself a “happy man.”

Mirville thought to herself, “Is this actually happening?”

Jayden — now a “chunky” baby boy of over 17 pounds with a fluffy mohawk and a scar down the middle of his potbelly stomach — sat in his Brooklyn Center apartment on a recent Tuesday, trying to yank at his mother’s hair.

Their apartment is full of baby gear such as a crib received during a baby shower Mirville’s co-workers at the HCMC pediatric unit later threw for the family.

Beamon said the baby, who was dressed in an “ALWAYS be HAPPY” T-shirt, loves to play and bite. He’s learning how to spit and getting close to sitting up on his own.

The parents say he’s quickly catching up in development.

Aside from an infection sending Jayden back to the hospital for a few weeks, recovery — consisting of care such as speech therapy — is continuing smoothly.

Watching his baby biting down on his fingers and drooling, the father said it “feels like victory.”

Mirville said it’s easy for mothers to blame themselves. She tried to.

With her smiley son, whose favorite nursery song is “I Love You, You Love Me,” in her arms, though, she reflected: Had she not hustled to the hospital after the movie, Jayden wouldn’t have made it.

“He did it,” she said. ”My baby boy did it."