Ebstein's anomaly is a rare congenital heart defect characterized by an abnormality of the tricuspid valve, which is one of the four valves in the heart. This valve separates the right atrium (upper heart chamber) from the right ventricle (lower heart chamber). In Ebstein's anomaly, the tricuspid valve is malformed and positioned lower than normal in the right ventricle.

Key features of Ebstein's anomaly include:

1. Abnormal Tricuspid Valve: The tricuspid valve in Ebstein's anomaly is not formed properly. Its leaflets are displaced downwards into the right ventricle, which can cause the valve to function poorly and lead to blood leaking back into the right atrium (tricuspid regurgitation).
2. Enlarged Right Atrium: Due to the regurgitation, the right atrium often becomes enlarged, and its function may be compromised.
3. Variability in Severity: The severity of Ebstein's anomaly can vary widely. Some individuals have a mild form and may remain asymptomatic for many years, while others have severe forms that cause significant heart problems from birth.
4. Associated Conditions: It is often associated with other cardiac abnormalities, such as atrial septal defects (holes in the wall between the left and right atria) or abnormal heart rhythms (arrhythmias).
5. Symptoms: Symptoms can include shortness of breath, fatigue, heart palpitations, and cyanosis (a bluish tint to the skin, lips, and fingernails), especially during exercise. However, symptoms vary based on the severity of the condition.
6. Diagnosis: Ebstein's anomaly is usually diagnosed with an echocardiogram (ultrasound of the heart), which can visualize the abnormal tricuspid valve and any associated heart defects.
7. Treatment: Treatment depends on the severity of the condition. It may include medications to manage heart failure or arrhythmias, oxygen therapy, and, in severe cases, surgery to repair or replace the tricuspid valve or to close an atrial septal defect.
8. Long-term Outlook: The long-term outlook for individuals with Ebstein's anomaly varies. Those with a mild form of the disease may live a normal life span with few complications. However, those with more severe forms may require ongoing medical management and possibly surgical interventions.

Management of Ebstein's anomaly often involves a multidisciplinary team approach, including cardiologists, cardiac surgeons, and other specialists, particularly when diagnosed in infancy or childhood. Regular follow-up and monitoring are important to manage this condition effectively.