Quail Eggs Paint Picture of Heart Defects in Fetal Alcohol Syndrome

Researchers seeking to better understand the causes of heart defects in babies born with fetal alcohol syndrome found that significant changes occur in an embryo’s heart function before the hallmark anomalies in cardiac structure emerge.

Prior to the formation of heart defects, the researchers found changes in cardiac blood flow in the embryos exposed to alcohol when compared with embryos without alcohol exposure.

“Our results indicated that ethanol-exposed embryos developed late-stage valvuloseptal defects,” the authors, led by Ganga Karunamuni of Case Western University, wrote. “At early stages, they exhibited increased regurgitant flow and developed smaller atrio-ventricular cardiac cushions, in comparison to controls (uninjected and saline-injected embryos). The embryos also exhibited abnormal flexion/torsion of the body.”

The research was conducted using quail embryos, which have heart development that is similar to humans. Using the imaging technique optical coherence tomography, the researchers compared embryos exposed to a single, large dose of alcohol with those that hadn't received alcohol.

“Our evidence suggests that ethanol-induced alterations in early cardiac function have the potential to contribute to late-stage valve and septal defects, thus demonstrating that functional parameters may serve as early and sensitive gauges of cardiac normalcy and abnormalities,” the authors wrote.

The researchers suggested that learning more about the functional changes in the early heart might allow for future interventions that redirect blood flow and prevent fetal alcohol syndrome–related heart defects before they form.

"With an average of 4 million U.S. pregnancies per year, there will be approximately 10,000 cases of alcohol-induced congenital heart defects," they wrote. "Continued study of the mechanisms involved in the development of alcohol-induced cardiac birth defects is warranted in order to implement effective treatments and/or prevention strategies."

Pertinent Points:
- Before the well-known cardiac anomalies of fetal alcohol syndrome emerge, there are significant changes in blood flow, according to recent research involving the study of quail embryos.
- Understanding the early functional changes of an embryo’s heart that has been exposed to large amounts of alcohol may provide a path for future prevention strategies or treatments in babies at risk for fetal alcohol syndrome.

References:

Karunamuni G, Gu S, Doughman YQ, et al. Ethanol exposure alters early cardiac function in the looping heart: a mechanism for congenital heart defects? Am J Physiol Heart Circ Physiol. 2013 Nov 22. [Epub ahead of print]