Ebstein's anomaly is a rare congenital heart defect where the tricuspid valve does not form properly, causing the lower right chamber of the heart (right ventricle) to function poorly. Key features include downward displacement of the tricuspid valve into the right ventricle, an enlarged upper right chamber (right atrium), and a small, non-functional portion of the right ventricle. Presentation varies from no symptoms to heart failure in infancy. Complications include arrhythmias, paradoxical embolism, and sudden cardiac death. Diagnosis is made based on echocardiogram findings and symptoms. Treatment involves medication, surgery, or heart transplant depending on severity.