That life-altering moment for the late-night comic has spurred a heated national debate about the ongoing Republican campaign to repeal the Affordable Care Act. On his show Tuesday night, Kimmel blasted one Republican senator in particular -- Louisiana's Bill Cassidy -- for having "lied right to my face."
Kimmel was referring to Cassidy's vow earlier this year to only support a health care legislation if it passed a "Jimmy Kimmel test" -- that a child born with a congenital heart disease like Billy Kimmel would "be able to get everything she or he would need in that first year of life," the senator said on CNN in May.
But the Graham-Cassidy Obamacare repeal bill, Kimmel argued this week, doesn't even come close to fulfilling that promise of protecting people with pre-existing conditions.
"Not only did Bill Cassidy fail the Jimmy Kimmel test, he failed the Bill Cassidy test," Kimmel said in a lengthy monologue Tuesday night. "He failed his own test."
Both Cassidy and Sen. Lindsey Graham, the bill's co-sponsor, have forcefully pushed back. "I am sorry he does not understand," Cassidy said on CNN Wednesday morning. He insisted that under his bill, "more people will have coverage and we protect those with pre-existing conditions."
Here's what would be at stake for Billy Kimmel and others with serious health conditions if Graham-Cassidy became law:
Billy Kimmel's heart condition
Tetralogy of Fallot with pulmonary atresia
, the condition that Billy Kimmel has, is a congenital heart defect in which there is a hole in the wall between the heart's left and right chambers. Without a valve connecting the right ventricle to the lungs, not enough blood reaches the lungs.
Those born with the condition are usually diagnosed as infants or young children, according to the American Heart Association, with visible symptoms that include skin that is bluish in color. (Kimmel said a nurse happened to notice that Billy's skin appeared to have a purple tint).
How is it treated and how much does it cost?
The life-long condition typically requires multiple procedures, including open-heart surgeries to reconstruct the connection between the heart and lungs and catheterization to help enlarge arteries. Even after the children get older, they will need constant monitoring and sometimes follow-up operations as adults.
Needless to say, it is an expensive condition to treat.
According to Dr. Roger Breitbart, the chief of Boston Children's Hospital's inpatient cardiology division, open heart surgery and hospitalization can easily cost upwards of hundreds of thousands of dollars, while catheterization procedures can be multiple tens of thousand of dollars each. The total lifetime cost could easily surpass $1 million, he said.
Breitbart has treated many children with the condition and said some of his patients who are now teenagers "wouldn't be alive if they had not had the series of treatments. They may have had three or four open heart operations and as many as a dozen heart catheterization procedures in the first six to eight years of life."
How does someone like Billy Kimmel fare under Obamacare?
Prior to Obamacare, Billy Kimmel could have found himself branded uninsurable for life.
Insurance companies routinely turned people with pre-existing conditions away or charged them sky-high premiums if they applied for coverage on the individual market. More than a quarter of non-elderly adults have health conditions that would have made them ineligible for coverage in this market, according to the Kaiser Family Foundation.
Plus, they often limited how much they'd be willing to cover annually or over one's life. Kids like Billy Kimmel would likely blow through the cap pretty quickly.
Those with employer policies fared better, but even there, it was possible to get hit. Health care bills were one of the leading causes of bankruptcy.
The Affordable Care Act changed all that. Insurers are no longer allowed to turn people away, nor charge them more, because of pre-existing conditions. And they must offer comprehensive policies that cover a wide array of treatments and medication. Plus, insurers cannot impose annual or lifetime limits on coverage of those essential health benefits.
What about the Graham-Cassidy bill?
It would depend on where Billy Kimmel lives. The bill would allow states to set up their own rules for coverage, an idea that Republicans generally favor because they say it lets each address its unique needs. For example, one state might keep many of Obamacare's protections, while another could loosen the rules considerably.
Graham-Cassidy would not let insurers turn away those with pre-existing conditions anywhere. But states could opt to once again allow carriers to raise premiums because of people's medical histories and to sell skimpier policies that don't cover Obamacare's 10 essential health benefits.
Also, insurers would be able to cap the amount they would pay for treatment outside what their states deems an essential health benefit.
"Families with young children with conditions such as this are likely worried most immediately about the pre-existing condition issue," Breitbart said about the Republican proposal. As for the lifetime cap, "one has to wonder what are such families going to do after we have saved their lives quite literally as children and then can't provide ongoing care."
All these changes are particularly troubling for those in the individual market since employers generally offer better coverage. And they are among the reasons why multiple patient advocacy groups, including the American Heart Foundation, have come out against the bill.
Kimmel: Not everyone is as fortunate as he is
The ABC late night host has made one thing clear as he has spoken about his son's diagnosis: His family is incredibly fortunate.
He has health insurance and the means to pay for his son's care. As much as he has used his son's diagnosis to draw public attention to the impact of various GOP proposals to gut Obamacare, Kimmel can at least rest easy knowing that his family can afford to pay for Billy's treatments.
It's a luxury that many other families don't have.
"If your baby is going to die and it doesn't have to, it shouldn't matter how much money you make," Kimmel said in May. "No parent should ever have to decide if they can afford to save their child's life. It just shouldn't happen. Not here."