Fetal Surgery May Treat Heart Defect
TUESDAY Sept. 29, 2009 -- Infants born with a rare heart defect may have better outcomes when surgery to repair the heart is done while the infant is still in the womb, Harvard University researchers say.
The condition, hypoplastic left heart syndrome, occurs when the fetus's left ventricle is underdeveloped and the heart cannot pump enough blood to sustain life. It affects about 1 in 10,000 newborns, and without open-heart surgery within a week of birth, these infants face death. Even with the heart repair, the children lead restricted lives and need at least one heart transplant, researchers say.
"Using the new procedure, in about 30 percent of the fetuses [with technically successful operations], there was an outcome of a two-ventricle circulation after birth," said Dr. Doff B. McElhinney, an assistant professor of pediatrics at Harvard Medical School and an associate in cardiology at Children's Hospital Boston.
The findings appear online Sept. 28 in Circulation.
How well the infants in the study will fare over the long term isn't known, but the researchers intend to follow them as they grow up, McElhinney said.
In fetuses, aortic stenosis usually progresses to hypoplastic left heart syndrome, the study explains. Prenatal intervention could reduce the total number of surgeries required over a lifetime, eliminate the need for a heart transplant and possibly improve the children's quality of life, he said.
According to the study, 51 of 68 procedures were considered technically successful, and 17 infants (33 percent of the 51) were born with a fully functioning heart.
The operation involves threading a catheter through the mother's abdomen into the fetus's heart. A balloon at the end of the catheter enlarges the aortic valve that controls blood flow from the left ventricle into the aorta and then into the body, McElhinney explained.
Over seven years, the researchers were able to establish criteria to determine which infants were likely to benefit from the procedure, which would not and when the operation would be most likely to succeed, McElhinney said. "This enables us to focus it more, and expose fewer mothers and fetuses to the risks of the procedure," he said.
The window for performing the procedure is narrow -- at around 20 to 21 weeks of pregnancy, McElhinney said. With time, experience and better technology, the success rate will get better, he added.
McElhinney is cautious about the impact of the new procedure and doesn't want to oversell its benefits.
"By no means is this revolutionizing the care for all fetuses with hypoplastic left heart syndrome," he said. "It's applicable only in a small subset of those with this disease, and it's working in a relatively small percentage of those in whom we attempt it," he said. And even infants who had a successful procedure needed additional procedures after birth, he noted.
Still, while not a "ringing success," he said it reinforces the belief that prenatal intervention can be used to change the development of serious forms of heart disease.
Dr. Steven E. Lipshultz, chairman of pediatrics at the Leonard M. Miller School of Medicine at the University of Miami, said that the study points the way to better treatment and outcomes for youngsters with this heart problem.
"This is a landmark study," Lipshultz said. Without this procedure, "every one of these kids would have needed open heart surgery in the first few days after birth," he said. Additional surgeries and multiple heart transplants are almost always necessary, he added.
Parents whose doctors think their baby might have hypoplastic left heart syndrome should act fast to find a program that will consider their child for a fetal operation, he said.
Dr. Ruben A. Quintero, professor and director of maternal-fetal medicine at the Miller School of Medicine, said he thinks that much more needs to be done to improve the procedure and increase the success rate before embracing the operation.
"What needs to happen now is that other centers use the experience of the Boston group to share their outcomes and try to improve on the limitations that the Boston group has outlined," he said. "This has happened in other areas of fetal therapy."
Once the surgical technique is ironed out, clinical trials should compare the outcomes of those undergoing the procedure with those who don't have it, Quintero said.
The American Heart Association has more on hypoplastic left heart syndrome.
Posted: September 2009
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