Ebstein’s anomaly is a rare heart defect that involves a deformed and misplaced tricuspid valve and usually occurs along with other heart defects. In a normal heart, the tricuspid valve is located between the right upper chamber (atrium) and the right lower chamber (ventricle). It opens and closes at precise intervals, allowing blood to travel from the right atrium to the right ventricle, which then pumps the blood to the lungs to pick up oxygen.

In Ebstein’s anomaly, however, the tricuspid valve droops into the right ventricle and cannot close properly. Alternatively, the condition may be associated with malformations in the shape of the right ventricle or right atrium. Any of these conditions means that the blood flow between the right atrium and right ventricle is irregular. Instead of flowing in only one direction, blood is allowed to flow backward from the right ventricle into the right atrium through the tricuspid valve. This is known as tricuspid regurgitation. Ebstein's anomaly is the most important cause of tricuspid regurgitation.

In addition to problems with the right-heart anatomy, patients with Ebstein’s anomaly also tend to have associated heart defects, including a patent foramen ovale or an atrial septal defect (ASD). The ASD is the more serious of the two. An ASD is a hole between the left and right atria that allows oxygen-poor blood from the right atrium to mix with oxygen-rich blood in the left atrium. Additionally, about 10 percent of patients also experience abnormal heart rhythms (arrhythmias).

As a result of the various abnormalities, less blood receives fresh oxygen, which leads to cyanosis – a bluish tint to the skin because the body is not receiving enough oxygen-rich blood (a condition often called blue baby in infants).

The range of problems associated with Ebstein’s anomaly depends on the severity of the condition. Severe Ebstein’s anomaly is a life-threatening condition that can progress to heart failure or death and must be treated immediately. A person with mild Ebstein’s anomaly might show no symptoms until adulthood, and then show only mild symptoms.

Treatment for Ebstein’s anomaly depends on the severity of the symptoms and the extent of anatomical abnormalities. Mild Ebstein’s may be treated with medication to relieve the symptoms. More serious Ebstein’s will usually require open-heart surgery, usually early in life. After surgery, lifelong medical follow-up and close medical management will be necessary. For example, patients will need to take antibiotics before any dental, medical or surgical procedure to prevent a potentially life-threatening infection called endocarditis.

However, in most adults with Ebstein’s anomaly the condition is mild and does not require surgery, according to the American Heart Association.