Jimmy Kimmel experienced one of the most difficult times of his life when nurses and doctors noticed his newborn child, Bill had a heart murmur and had a blue color to his skin. Nothing prepares an expectant parent for bad news. But that experience became part of a national discussion recently, with the news that Jimmy Kimmel’s son was diagnosed with a congenital heart defect called tetralogy of Fallot with pulmonary atresia.Jimmy Kimmel and son Billy

The talk show host shared his emotional story after his son Billy’s first surgery in April and a second one earlier this month. His monologues highlighted hot-button issues about health care but also gave a national spotlight to a rare heart condition.

Off the Charts is a series featuring expert answers to questions about heart and brain health. This week we explore tetralogy of Fallot with pulmonary atresia.

Q: So, just what is tetralogy of Fallot with pulmonary atresia?

A: Tetralogy (teh-TRAL-o-je) of Fallot (fah-LO) is named for French physician Étienne-Louis Arthur Fallot and is a serious heart condition that occurs in five of every 10,000 babies. The more severe form with pulmonary atresia occurs in about one out of every 10,000 babies, according to the Centers for Disease Control and Prevention.

In a normal heart, the left side pumps oxygenated, or pink blood, to the body. The right side pumps less oxygenated, or blue blood, to the lungs. But babies born with tetralogy of Fallot have a collection of heart defects disrupting that setup. As a result, not enough blood is able to reach the lungs, and oxygen-poor blood flows to the body. That’s why many children with the condition are blue.

In tetralogy of Fallot, there are four (“tetra”) defects.

The wall between the heart’s lower chambers, the left and right ventricles, has a hole. This is called a ventricular septal defect. The pathway leading from the heart to the lungs, called the pulmonary valve, is narrowed or obstructed. This is called pulmonary stenosis. The aorta, the main artery that is supposed to carry oxygen-rich blood from the heart to the body, is malformed and sits above the hole in the wall between the chambers. This is called an overriding aorta. In the fourth defect, the muscle surrounding the lower right heart chamber thickens from overwork. This is called right ventricular hypertrophy.

In pulmonary atresia, the valve from the heart to the lungs is completely obstructed. So blood has trouble flowing to the lungs to pick up oxygen.

In Billy Kimmel’s case, hours after birth, nurses and doctors noticed a heart murmur and his blue color. Tests confirmed tetralogy of Fallot with pulmonary atresia. The first surgery opened his pulmonary valve. The second closed the hole between the two chambers. A third, in the future, most likely will involve a new valve.

Doctors have been operating on tetralogy of Fallot patients since at least the 1960s, said Gerald Marx, M.D., an associate professor at Harvard School of Medicine. He points to success stories such as Olympic gold medal snowboarder Shaun White, who appeared on Kimmel’s talk show and talked about his tetralogy of Fallot.

“We have many patients who are older and had repairs and are doing very well,” said Marx, who has been practicing for 40 years and is senior associate of cardiology at Boston Children’s Hospital.

But the condition – especially with the rarer pulmonary atresia – has a wide range of severity, he said. Outcomes, surgeries and long-term prognosis all depend on the individual collection of defects and the child’s anatomy. Some children have more fragile and smaller pulmonary arteries.

“We’ve had a lot of important surgical and catheter interventions, to improve the outcomes for tetralogy of Fallot with pulmonary atresia,” Marx said. “In particular, catheter interventions can be performed to dilate and or stent the pulmonary arteries, especially when the vessels are small or obstructed.”

This past summer, at Cedars-Sinai Hospital in Los Angeles, a cardiologist implanted the first-of-its-kind pulmonary heart valve in a clinical trial. The device, which was placed in an adult, is a self-expanding, stent-like implant that can be delivered via a small incision in the leg. It potentially could spare some patients from multiple open-heart surgeries.

Cedars-Sinai is where Billy Kimmel was born and where nurses and doctors first diagnosed his heart defect. He had his surgery at Children’s Hospital of Los Angeles.

The experimental valve is the most recent example of how medicine has been making leaps in its treatment of congenital heart disease. But researchers have been hopeful for a few decades.

In 1994, a report in the Texas Heart Institute Journal looked at three centuries of advances in tetralogy of Fallot, which was first described in 1673. The article chronicled how the condition has been treated over the years, with advances in open-heart surgery and treatment of infants.

And it continued its hope of new directions for the next century.

“The challenge of the next 100 years,” researchers wrote, “lies in increased understanding of the molecular biology of the defect and in preserving the blend of humanism, scholarship, and skill that have graced the advances of the past 3 centuries.”