Heart Abnormality May Be a Cause of SIDS

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A new cause of sudden infant death syndrome (SIDS) may have been discovered by scientists at the University of Strasbourg, who say they have identified a heart abnormality in some victims of SIDS. The anomaly affects the regulation of the heartbeat and causes the heart to slow down and to then stop.

According to the American Sudden Infant Death Institute, the rate of SIDS has fallen by more than 50 percent since 1983, due largely to educating parents and caretakers about the importance of babies sleeping on their backs. Yet more than 2,500 infants still die each year in the United States from this disorder, and thousands more around the world.

However, SIDS still remains the number one cause of death in children between one month and one year old in developed countries. Most SIDS deaths occur when babies are between two and four months of age. Other risk factors for SIDS include premature or low birth weight, exposure to tobacco smoke, and being black or Native American.

In the new study, French scientists say they have found that a chemical called acetylcholine, which is produced by the cardiac nerve and which controls the heart rate, is absorbed in great amounts by the heart in some infants who have died of SIDS. This chemical then causes the heart to eventually stop.

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The Strasbourg team made their discovery when they examined the heart or blood samples from 18 victims of SIDS and 19 children who died a violent or sudden death that was not related to any heart condition or abnormality. All the infants were between one and nine months old.

When the investigators examined heart tissue samples taken from nine of the SIDS victims and eight from the control group, all but one of the nine SIDS victims showed high levels of acetylcholine and an increased number of acetylcholine receptors in the heart. This caused the scientists to believe that the cardiac nerve in such infants may become overly active and slow down the heart too much. This idea was supported by finding an enzyme in the white blood cells in six of 10 blood samples taken from the remaining SIDS victims and control group.

The research team is hoping to find signs of the heart abnormality in humans so it can be identified through a routine blood test administered to newborns. Professor Pascal Bousquet, of the Faculty of Medicine at Strasbourg University Hospital noted that “We have found the marker in white blood cells and if it exists in humans we will be able to identify children at risk of SIDS.”

If the researchers are able to identify which infants are at risk of SIDS, then medications can be used to control the heart rate and block the receptors in the heart.

The discovery of a heart abnormality that may be a cause of SIDS is an important one. The Foundation for the Study of Infant Deaths noted that “This research may help to explain why some infants are particularly vulnerable.” Additional research is needed to further understand this heart abnormality and how it can be treated to prevent SIDS in vulnerable children.

SOURCES:
American Sudden Infant Death Institute
Foundation for the Study of Infant Deaths
Guardian, Mar. 5, 2010

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