Inside the Tragic Health Battle of Jimmy Kimmel's Son Billy

On April 21, 2017, Jimmy Kimmel and his wife, Molly McNearney, welcomed their son William "Billy" Kimmel. But days after the baby was born, the doctors diagnosed him with a rare and potentially dangerous cardiac defect called Tetralogy of Fallot.

The father-of-four first opened up about his son's harrowing health battle in an emotional monologue on Jimmy Kimmel Live! in May 2017, confirming Billy was diagnosed with Tetralogy of Fallot with pulmonary atresia.

"The room started to fill up. More doctors, nurses, and equipment started coming in and they determined that he wasn’t getting enough oxygen into his blood," Jimmy told his viewers. "It’s a terrifying thing."

The medical staff reportedly took Billy to the neonatal intensive care unit after noticing he was a bit purple, and they later determined something was wrong with his heart.

Billy underwent an emergency open heart surgery when he was just three days old.

“Dr. Vaughn Starnes opened his chest and fixed one of the two defects in his heart. He went in there with a scalpel and did some kind of magic that I couldn’t even begin to explain,” Jimmy said at the time. “He opened the valve, and the operation was a success. It was the longest three hours of my life.”

Months later, Jimmy took to Instagram to give his followers an update.

"Billy is three months old today and doing great. Thanks for all your love & support and please remind your Congresspeople that every kid deserves the care Billy got," he captioned a photo of his son in July 2017.

At seven months old, Billy underwent his second operation. Jimmy took a week off from his show to be with his son, and the procedure was fortunately successful.

Meanwhile, Molly tweeted a plea to other parents amid the challenge.

"If your children are healthy, be thankful. And do something to help those whose children are not," said the matriarch on X.

Speaking with E! News in October 2022, the 56-year-old comedian shared an update while he was at the Children's Hospital Los Angeles.

"He's doing great. He's a very funny kid," Jimmy said at the time. "He loves Spiderman, jumping on my head and doing all the things we tell him not to do."

He added, "They fixed his heart. The heart is a super important part of the body...They fixed them up real good, so we're very grateful."

Still, Jimmy clarified Billy still needed one open-heart surgery despite his good prognosis. Although he tried to explain it to his son, Billy reportedly had almost no interest in learning about his health battle.

In April, Jimmy gave another update as he celebrated his son's birthday.

“Billy turns 7 today and is doing great thanks to the doctors, nurses, therapists and staff at @ChildrensLA & @CedarsSinai,” the former The Man Show co-host captioned his Instagram post. “Billy is asking friends ‘to give $7 because I’m seven to help kids in the hospital.’ (he also wants a spy kit) His goal is ‘to raise $100 to help sick kids.’ If you’d like to donate – thank you and link in bio.”

Years after undergoing his first and second open-heart surgery, Billy entered the operating room for his third and — hopefully — final procedure.

"We went into this experience with a lot of optimism and nearly as much fear and came out with a new valve inside a happy, healthy kid," Jimmy captioned the post.

After the procedure, Dr. Vaughn appeared on Good Morning America — with Jimmy's permission — and spoke with Matt Gutman regarding the Kimmel family's journey. He said Jimmy and Molly got caught by surprise by their son's heart condition.

"They thought Billy was going to be perfectly normal and was until two or three hours after delivery. That's when the nurse noted that the child was somewhat blue and sounded the alarms," he said. "[It] got to be the most scary, terrifying thing that a parent goes through."

Dr. Vaughn said Billy's Tetralogy of Fallot was the "very severe form" of the disease since the child's heart had no connection between its right ventricle.

Nevertheless, the procedure was an instant success.

Tetralogy of Fallot, named after French physician Étienne-Louis Arthur Fallot, occurs when two or more congenital heart defects are detected in a patient.

The American Heart Association explains that Tetralogy of Fallot features four problems: "a hole between the lower chambers of the heart, obstruction from the heart to the lungs, the muscle surrounding the lower right chamber becomes overly thickened and the aorta (blood vessel) lies over the hole in the lower chambers."

Per the National Institutes of Health, the condition affects about five of every 10,000 live births.