(CNN) The surgeon starts to tear up as he describes taking the baby off life support.
He'd lost patients before; that's the reality when you operate on tiny, malfunctioning hearts.
But this death was different, the surgeon says.
This baby didn't have to die.
The surgeon spoke on the condition of anonymity because he doesn't have permission from his employer to speak about the baby's case.
The infant had been transferred to his hospital after having surgery at St. Mary's Medical Center in West Palm Beach, Florida. He and his team tried to save her.
"We were called in late to fix a problem caused by someone else," the surgeon says.
"It makes you angry when you have to fix someone else's lethal mistakes."
After a CNN investigation into the deaths of babies after heart surgery at St. Mary's, the hospital shut down its program in August.
At least nine babies died after heart surgeries there over the course of 3½ years, from the end of 2011, when the program started, and June 2015. Another infant, Layla McCarthy, was paralyzed after heart surgery at St. Mary's and was transferred to a different hospital for treatment, and survived. Jashnide Desamours, a newborn, went into cardiac arrest and was put on life support after heart surgeries at St. Mary's. Her mother asked for her to be transferred to a different hospital, where she had surgery and survived.
The program at St. Mary's is closed, but surgeons who study the issue say there are other programs still operating on children's hearts that aren't very good at it.
The surgeons say those children are sent to them in dire condition.
"I've seen botched surgeries. I've seen cases where they did the wrong surgery," says Dr. Edward Bove, chief of the department of cardiac surgery at the University of Michigan Health System.
Dr. Joseph Forbess, director of cardiac surgery at Children's Medical Center Dallas, says he's seen the same.
"By the time they send them to us, the child is dying," he says. "It's very difficult for us because you know you could probably have done it better. You keep your emotions in check, but in some ways you're ticked off and sad at the same time."
Now some doctors are saying enough is enough.
On the heels of CNN's report about babies' deaths at St. Mary's, a team of researchers has proposed that policy makers consider telling some hospitals to stop doing complex heart surgeries on children.
"[CNN's] investigation has stimulated a long overdue discussion," Dr. Sara Pasquali, associate professor of pediatric cardiology at the University of Michigan wrote recently in the Journal of the American Medical Association.
Consider a surgery called the Norwood. Surgeons essentially have to replumb a newborn's heart, which is about the size of a strawberry. The risks are high: Out of more than 100 operations that surgeons do on children's hearts, the Norwood has the third-highest death rate, according to a ranking by the Society of Thoracic Surgeons.
Some hospitals are better at performing Norwoods than others. At the most successful programs, one out of 10 babies dies after getting a Norwood. At the least successful, four out of 10 will die, according to Pasquali's article.
And it's not just the Norwood. A study of 73 hospitals that looked at more than 58,000 congenital heart operations found that for the most complicated type of pediatric heart surgeries, hospitals' performance varied wildly. Some hospitals had mortality rates as low as 6.5%, but others were as high as 38.4% -- that's more than a six-fold difference.
"The quality of care is not the same at all hospitals that provide pediatric cardiac surgery," says Dr. Jeffrey Jacobs, chairman of the Society of Thoracic Surgeon's National Database Workforce.
But as CNN has reported, parents usually have no way of knowing whether their child is at one of the successful hospitals, or one of the unsuccessful hospitals.
"It makes me sad and frustrated and at some levels incensed," says Dr. Charles Fraser, the head of the pediatric heart surgery program at Texas Children's Hospital in Houston.
A few private insurance companies have started to actively encourage parents to send their children to hospitals with low death rates.
But not Medicaid. The government program has mortality rate data -- it insures 40% of all children with congenital heart defects -- but it won't tell parents which hospitals are the best, or the deadliest.
Doctors who care for children note that the federal Center for Medicare and Medicaid Services reveals death rates for many adult surgeries, yet it remains silent about heart surgeries on vulnerable babies.
"It's puzzling that they don't ask some basic questions about quality," says Fraser. "They pay, but they don't know what they're paying for."
When CNN asked Aaron Albright, a spokesman for the Centers for Medicare and Medicaid Services, about this issue, he wrote in an email, "let me see if CMS has a roll [sic] in this," and didn't send any further response.
There are many reasons why one hospital might be better than another at operating on tiny hearts, but this is a major one: practice.
Simply put, when a surgical team gets more practice fixing complicated heart defects, the team gets better at it.
And it's not just practice in the operating room. Bove, the University of Michigan surgeon, says many times he's seen experienced nurses save children's lives by picking up on subtle changes after the surgery, changes they've learned to notice through years of experience.
Statistics bear this out.
According to a study cited in Pasquali's report, when babies had the Norwood at an experienced center, the death rate was 16.9%, but when babies had the operation at a less experienced center, the death rate was 36.5%.
Pediatric cardiac surgery and pediatric cardiac care require mastery of multiple critical, volume-related skills," notes Jacobs, a professor of surgery at Johns Hopkins who has extensively studied death rates at pediatric heart surgery programs.
"The more operations you do, the better you perform."
Many hospitals don't get much practice. According to Society of Thoracic Surgeons data obtained by CNN, 32 out of 113 hospitals are considered low volume, meaning on average they perform fewer than 100 congenital heart procedures a year.
Some hospitals are extremely low volume. St. Mary's performed 23 operations in 2013, according to a review done for the state of Florida.
With just 23 cases a year, "It would be easy to make a total mess with newborn babies," says Dr. Roger Mee, the former chief of pediatric heart surgery at the Cleveland Clinic.
A spokeswoman for Tenet Healthcare, which owns St. Mary's, did not return emails from CNN requesting comment for this story.
Smaller programs like St. Mary's often hire only one pediatric heart surgeon.
"What if that one surgeon is on vacation when a child takes a turn for the worse?" says Fraser, the surgeon at Texas Children's Hospital, which has six pediatric heart surgeons. "The margins of error can be so narrow with some children. I know I've rescued some of my colleagues' patients when they were on vacation or maybe just in the operating room with another case, and they've rescued mine."
"It just mystifies me how a program can have only one surgeon," he adds. "It just mystifies me."
CNN reached out to several relatively low-volume hospitals that have only one surgeon. Most did not respond, but some that did say they arrange to have a surgeon from a larger center be on call and also perform the more complicated surgeries.
Telling low-performing hospitals to stop doing complicated surgeries might sound extreme, but there is some precedent.
In Britain, the National Health Service closed poorly performing pediatric heart surgery programs after dozens of babies died in the 1990s.
But surgeons fought tooth and nail to keep their programs alive, says Dr. Martin Elliott, a cardiac surgeon at the Great Ormond Street Hospital for Children in London who's written extensively about the closures.
Elliott says surgeons in the overwhelmingly male and very macho specialty of operating on children's hearts didn't want to admit they weren't adept at performing technically difficult operations.
"It's how they weigh their cojones!" Elliott wrote in a lecture last year. "Surgeons are very competitive."
Experts say it would be even harder to close poorly performing programs in the United States.
First, the United States doesn't have a central governmental authority comparable to the National Health Service.
Second, the United States is much larger geographically, and so families would likely have to travel farther if centers were closed.
Third, as in Britain, surgeons would fight to keep their programs open for reasons of ego and prestige.
But in the United States, these experts say, they would also do so because of money.
According to a study by researchers at Emory University, one Norwood procedure can bring a hospital more than half a million dollars.
Over the course of a year, a single child with a heart defect can ring up charges of more than $5 million, according to Optum, a health services firm that works with insurance giants like UnitedHealthcare.
"Doctors are under pressure from the administrators at their hospitals not to let these money-winning patients out of the hospital," says Mee, the former Cleveland Clinic surgeon who is now retired.
Hospitals with the poorest performance often make the most money per child. According to Optum, hospitals with the highest mortality rates for pediatric heart surgery are more than twice as likely to charge over $1 million per case compared to hospitals with lower death rates, because children tend to have longer hospital stays at the poorer performing hospitals.
Ten years ago, after seeing high death rates and high expenditures at poorly performing hospitals, Optum started to encourage families to use one of 20 "centers of excellence" around the country that have lower death rates.
They say it has worked. The death rate for patients treated at "centers of excellence" is 55% lower than for those treated at hospitals that are not centers of excellence, based on Optum's analysis of 2,570 cases and deaths up to one year after discharge, according to Dr. Jon Friedman, chief medical officer for the Optum's complex medical conditions program.
If families don't live near one of the designated hospitals, their insurance company pays for airfare and hotel for both parents. Another insurance giant, Aetna, has a similar program.
Friedman points out that the children who died at St. Mary's could have had their surgeries at one of Optum's centers of excellence, Nicklaus Children's Hospital in Miami, which is a 90 minute drive from St. Mary's and has a lower death rate than the national average, according to data on the hospital's website.
"We believe these were disasters that could have been avoided," Friedman says.
"I want to send your kid for heart surgery where I would send my kid. And I would send my kid to a center of excellence."
Pasquali, the author of the recent Journal of the American Medical Association report, says she feels the same way.
"It's time to re-examine how we deliver care to these vulnerable children," she says. "We would never have designed the system to look like this."
CNN's John Bonifield contributed to this report.