What is Ebstein's anomaly?

What is Ebstein's anomaly?

Ebstein's anomaly, also called Ebstein's malformation, is a rare, congenital (present at birth) heart defect.

In patients with Ebstein's anomaly, the valve between the chambers on the right side of the heart (the tricuspid valve) does not close correctly. The right side of the heart is where blood returns from the rest of the body and gets pumped out to the lungs to pick up oxygen again.

The tricuspid valve has three small flaps (leaflets). Normally, these leaflets open so that blood can flow from the right atrium (the top chamber of the heart) down into the right ventricle (the bottom chamber of the heart). The valve closes while the heart pumps so that blood cannot flow backwards. (See image of the heart's anatomy)

If you have Ebstein's anomaly, the flaps on the tricuspid valve are abnormally shaped, too large or adhered to the heart wall so they cannot move. It's not unusual for two of the valve flaps to be down in the ventricle where they don't belong. As a result of these abnormalities, the valve cannot open and close correctly, and blood can leak backwards into the atrium.

The misplaced valve flaps in the ventricle cause a section of the ventricle to become part of the right atrium. This creates an over-sized right atrium and also causes the right ventricle to expand as it pumps harder and harder to push the blood to the lungs. Over time, the enlarged right side of the heart weakens and heart failure develops.