Ebstein's anomaly is a congenital downward displacement of the tricuspid valve (located between the heart's upper and lower chambers on the right side) into the heart's right bottom chamber (or right ventricle). The major problem with this abnormality is that the tricuspid valve may be leaky or regurgitant.
If it is very leaky, blood goes backward instead of forward into the pulmonary artery every time the right ventricle contracts because the resistance in the right atrium is usually lower than the lungs. The amount of leakiness varies from minimal to very severe. Mild abnormalities with minimal leakiness may not ever require any intervention. With severe leakiness, intervention may be required soon after birth.
With severe Ebstein's anomaly, the leaky valve causes the right atrium to become very large. In fact, the right atrium may take up a large portion of the chest so that there is no room for the lungs. Sometimes, this improves with time. If not, surgery may be recommended.
Heart with Ebstein's Anomaly