Surviving a Broken Heart

By putting up the money to advance stem cell research, Proposition 71 also puts the scientific scrutiny of the world on California.

by Katie Sweeney

At birth, the baby is pink and squirming, with a loud cry and the requisite 10 fingers and 10 toes. But this healthy appearance is deceiving. In fact, the left side of the baby’s heart is severely underdeveloped. In just a few days, open-heart surgery will be needed to repair the defect.

In decades past, a baby born with only half of its heart working would have a slim chance of survival. But today, a child born with this kind of severe congenital heart defect has a good chance of survival—and of a normal life.

“In the ’60s and ’70s, many of the complex forms of heart disease were fatal in infancy,” says Roberta Williams, M.D., vice president for pediatrics and academic affairs at Childrens Hospital Los Angeles and chair of the Department of Pediatrics at the Keck School of Medicine of USC. “Now, the vast majority are reaching adult life, and most of them are quite healthy.”

That is good news because congenital heart defects are the most common birth defect, occurring in about eight of every 1,000 live births. While many heart defects are relatively mild, the more severe ones often are fatal without surgical intervention during the first days and weeks of life.

Although heart transplants are done in some cases, they are not the norm, due to the lack of available donors and the potential for rejection throughout the child’s life. The solution lies in a combination of earlier diagnosis, surgical advances and improved care, all of which may allow surgeons to repair an infant’s tiny heart, which is usually no bigger than a walnut.

Growing a heart

In most cases, there is no known reason why a heart defect occurs, although genetic errors are presumed to be the cause. But considering the complexity of the heart’s development, it seems amazing that it ever turns out right.

The fetal heart begins beating at about three weeks, making it the first organ to function. Initially, it is a tiny, pulsing tube, but over the next dozen or so weeks, that tube grows quickly, looping around and folding on itself to create four chambers—two atria and two ventricles—as well as four valves and the circulatory, coronary, electrical and lymphatic systems. All during this intricate process, the heart sustains the fetus’ life.

If all goes well, the newborn baby will have a healthy heart, a tireless workhorse that pumps blood continuously throughout the circulatory system. The right ventricle will pump blood to the lungs to get fresh oxygen, while the left ventricle will pump the oxygen-rich blood out to the body to nourish its tissues and organs. The valves will open and close to let blood flow in only one direction.

Occasionally, though, something goes wrong during the heart’s development, resulting in a defect. These defects can range from small “holes” between the chambers of the heart to major malformations, such as missing or underdeveloped chambers or vessels attached to the wrong places.

“There’s a wide range of things that can happen to the development of the heart and arteries during the embryology of a developing child,” says Vaughn A. Starnes, M.D., Hastings Professor, chair of the Department of Cardiothoracic Surgery at the Keck School of Medicine and director of the Heart Institute at Childrens Hospital Los Angeles, one of the largest pediatric heart centers in the United States.

According to Starnes, heart problems vary so much that no two children have the exact same problem; nor is there a typical surgery that is performed. For example, he says, at the Heart Institute, surgeons perform a constellation of 20 to 30 different surgeries on a routine basis, operating on more than 800 children a year.

Many of the surgeries are extremely complex, requiring not just skilled and experienced surgeons, but a team of specially trained nurses, physicians and therapists to care for children before and after surgery. For this reason, the delicate operations are performed at specialized pediatric heart centers such as the Heart Institute at Childrens Hospital.

Repairing a heart

One of the most complex surgical repairs is for hypoplastic left heart syndrome, a condition where the left side of the heart is underdeveloped, leaving a baby with a two-chambered heart instead of the usual four chambers. While surgeons are unable to use tissue to build two new chambers, Starnes explains, they can reconstruct the heart to function using only the two working chambers.

The reconstruction is done through a series of three open-heart surgeries. The first, performed shortly after birth, enlarges the baby’s too-small aorta with homograft tissue, usually an adult artery that has been donated. The surgeon connects the baby’s pulmonary artery to the reconstructed aorta using a synthetic tube. The right ventricle is then able to pump blood to both the lungs and the body.

The second surgery is performed when the baby is about 6 months of age, and the third is done around age 3. Each operation progressively improves the child’s circulation so that blood can flow to and from the lungs and bypass the defective left side of the heart.

Lifelong follow-up care is needed. Patients usually have to take heart medicines and are at risk of developing problems such as arrhythmias, which are irregular heart rhythms. Still, even with these conditions, many lead fairly normal lives.

“Around 70 percent of these kids will be able to do the things that their peers do, like play soccer and T-ball and go to school,” says Childrens Hospital cardiothoracic surgeon Winfield Wells, M.D., associate professor of cardiothoracic surgery at the Keck School.

Other defects can be corrected with just one surgery, for example, when the main arteries—the aorta and pulmonary artery—are connected to the wrong chambers. This means that most of the blood returning from the heart to the body is pumped back out without first going to the lungs to get oxygen. A baby with this condition is often called a “blue baby” because of the blue tinge of color to the skin, indicating a lack of oxygen in the bloodstream.

To correct this defect, surgeons perform an arterial switch operation in the baby’s first days of life, in effect “re-wiring” or redirecting the arteries to the proper ventricles.

For still other problems, surgery is unnecessary. Minor defects often resolve on their own, Wells says, while some defects can now be corrected using catheter-based interventions. Just as adult hearts are repaired using catheters, a pediatric cardiologist can guide tiny devices through catheters to various places within the heart to open valves and close vessels and openings in the heart.

Many procedures that used to require open-heart surgery are now performed using catheters, Wells says, so children may enter and leave the hospital in the same day.

Discovering heart defects

Ironically, many babies with serious heart defects appear healthy at birth and may even be sent home. That is because the heart’s circulation is different in the womb, where the baby gets its oxygen from the mother’s placenta. The trouble often begins a few days after birth, when a passageway between the left and right sides of the heart closes, as it normally should in all infants. But a baby with a faulty heart will start to struggle.

In the past, it was common for surgeons to perform only palliative cardiac procedures on infants, and then perform the total repair when the child was older. But that approach meant the baby’s heart continued to develop abnormally.

“We think intervening earlier is better,” says Michael J. Silka, M.D., professor of pediatrics at the Keck School and chief of the division of cardiology at Childrens Hospital. “For the first year of life, the heart has a lot of ability to adapt and remodel.”

Heart defects also are being diagnosed earlier, often before birth. Since the heart develops early in pregnancy, problems can be detected by the time the fetus reaches 18 to 22 weeks, and sometimes as early as 10 to 14 weeks, says Mark Sklansky, M.D., associate professor of pediatrics at the Keck School and director of fetal cardiology at Childrens Hospital.

If an obstetrician spots an abnormality in the fetal heart during a routine pregnancy ultrasound exam, the mother is referred to a specialist for a fetal echocardiogram. This targeted, high-resolution ultrasound study provides a detailed picture of the fetal heart, so specific defects can be identified, parents can be counseled and appropriate delivery plans can be arranged.

Sklansky also is involved in research looking at 3-D and 4-D images of the fetal heart. With this technology, a specialist can acquire a complete volume of the fetal heart in just two seconds, interactively visualize the heart from all viewpoints, including “surgeon’s eye” views, and then continue to evaluate the fetal heart after the patient has gone home.

Prenatal diagnosis helps parents emotionally prepare for having a seriously ill baby and gives them time to evaluate options and make important decisions about treatment, Sklansky says.

But fetal screening is not perfect, he adds: “While more obstetricians are looking closely at all aspects of the fetal heart during routine exams, many defects continue to be missed or are nearly impossible to pick up prenatally.”

Finding better fixes

Although researchers and physicians have made huge leaps in treating congenital heart disease, there is still room for improvement. One problem that remains is finding better heart valve substitutes for children.

Currently, when a child needs a new heart valve, surgeons insert one made from donated human tissue. The problem is that the valve does not grow with the child. So a child must endure major surgery every few years to put in bigger replacement valves.

“If you put one of these valves in someone over age 60, it’ll last a lifetime,” Wells explains. “Put that same valve in a 10-year-old, and you have to replace it in two years.”

To solve this problem, researchers at Childrens Hospital and USC are studying how to grow heart valves using the patient’s own cells. The valve would then grow with the child and potentially last a lifetime.

Also, as an alternative to myriad invasive surgeries, researchers in Europe have started to deliver heart valve replacements via catheters. And there is ongoing research into the genetics of congenital heart disease, with a few defects already linked to a particular chromosome.

“There’s probably a genetic marker for all of these defects,” Wells speculates. “Somewhere in the code, there’s a typographical error, but the relationships are complex. I think we will eventually find them, but it’s going to be in the distant future.”

Reaching beyond childhood

The success in treating children with congenital heart disease has created a new problem: What happens when these children reach adulthood?

Children born with complex heart defects often continue to need specialized care as adults, and that can be hard to find, says Starnes. To fill this need, he and his Keck School colleagues started a clinic especially for adults with congenital heart disease. The new program will follow, evaluate and treat patients if they develop arrhythmias or other heart problems.

“Oftentimes, these patients go to a community hospital, and rather than being seen as horses, they’re seen as zebras,” Starnes says. “If a physician is not accustomed to seeing these conditions, it’s difficult to make heads or tails of them. Now patients don’t have to give up the specialized care they have been receiving since birth.” ?

Katie Sweeney is a freelance writer based in Los Angeles.

For more information about treatment of children with congenital heart disease, or to learn more about The Doctors of USC, call 1-800-USC-CARE.