Prenatal diagnoses of fetal heart conditions may not be as helpful in predicting the survival of newborns as once hoped, according to a new study at the University Prenatal Heart Clinic. While in utero diagnoses improve treatment and allow for family counseling and planning, researchers say that other risks factor significantly into the infant’s survival.
“We had thought that it would be helpful to know ahead of time if the infant had heart defects, but it doesn’t always pan out that way,” said Carlen Gomez, the study’s leading investigator and director of the University Prenatal Heart Clinic.
The study examined the survival rate of fetuses diagnosed in utero with Hypoplastic Left Heart Syndrome – a defect in which the heart’s left ventricle is too small to help pump blood through the body. Seventy-six infants at the University Prenatal Heart Clinic were involved in the study, conducted between June 1998 and December 2001.
The researchers’ findings concluded that only half of the risk factors could be identified through prenatal diagnoses. Even with early detection of HLHS, infants with at least one other risk factor – often undetectable until birth – had a significantly lower chance of survival.
The study identifies four such risk factors associated with a decreased survival rate – premature birth or low birth rate, obstruction of the pulmonary venous return, additional heart defects and other non-heart related abnormalities.
“Some defects just can’t be identified before the birth of the child,” Gomez said. “Premature birth, for example, cannot be detected in utero and is a significant factor in determining if the child survives.”
While 38 of the fetuses in the study had one or more risk factors, only 16 of them were identified as being at a high risk through prenatal detection. More than 50 percent of the fetuses with one risk factor, and 67 percent with two or more did not survive.
But researchers showed that 80 percent of the infants who had HLHS and no other risk factors survived through the first surgery.
Only 5 to 7 percent of children with congenital heart disease are diagnosed with HLHS, which is responsible for 25 percent of all cardiac related deaths within the first week after birth. This was only in cases where a three-phase surgery or a heart transplant was not performed.
The University Prenatal Heart Clinic diagnoses an estimated 50 fetuses with HLHS a year, Gomez said.
Based on their findings Gomez said the most important thing they can do is to inform families of the significance of these risk factors.
“When we counsel families with fetuses that have had prenatal diagnoses, it is important to give them a realistic picture of what we can and cannot predict,” she said.
In the future, Gomez said she hoped for the improvement of detection for these risk factors, as well as having the ability to intervene and correct problems in utero.
“There is the potential to intervene,” Gomez said, adding that only the Boston Children Center has performed several interventions. “I feel that intervention will be much more common in the future and hope that it will become a real option very soon.”
These findings from the University Congenital Heart Center’s Prenatal Cardiology Clinic will be presented this week at the 52nd annual Scientific Session of the American College of Cardiology in Chicago.
Another study presented yesterday at the conference indicates that ridding bars and restaurants of smoke quickly improves health for everyone. The study showed that the rate of heart attacks fell by more than half in Helena, Montana after voters passed a broad indoor smoking ban.
Other important research introduced at the conference indicated the drug hydroxyurea used to reduce the pain of sickle cell anemia can also significantly lower death rates.
The study of adult sickle cell patients showed that those who used hydroxyurea capsules at least periodically for nine years had a 40 percent lower mortality rate than those who never used the drug.
-The Associated Press contributed to this article.