Ebstein anomaly is a rare congenital malformation of the heart that occurs in approximately 1 per 200,000 live births, which accounts for about 0.5% of all cases of congenital heart disease. In this condition, the tricuspid valve is located lower than normal, so the upper part of the right ventricle becomes incorporated into the right atrium making the right ventricle too small and the right atrium too large. Besides that, leaflets that make up the tricuspid valve opening are malformed allowing blood to leak back into the atrium after it has flowed into the ventricle. This backward flow of blood also contributes to the size anomaly of the atrium and the ventricle. The cardinal symptoms in Ebstein's anomaly are cyanosis, right-sided heart failure, arrhythmias, and sudden cardiac death. Newborns with this condition usually appear blue at birth, have difficulties in breathing, feeding, and may require immediate surgical treatment in infancy. Most adults with this condition only have mild symptoms and may have a normal life expectancy. Ebstein's anomaly is commonly associated with other heart problems including atrial septal defect, arrhythmias, pulmonary stenosis, and arrhythmias.
The causes of this condition are still uncertain, but genetic and environmental factors are both thought to play a role. For example, it is found that women who ingest lithium during the first trimester of pregnancy are at higher risk for having children with this condition. Also, risk is higher in whites than in other races.