Ebstein's anomaly is an abnormality in the tricuspid valve. The tricuspid valve separates the right atrium (the chamber that receives blood from the body) from the right ventricle (the chamber that pumps blood to the lungs).
In Ebstein's anomaly, two leaflets of the tricuspid valve are displaced downward into the pumping chamber. The third leaflet is elongated and may be tethered to the wall of the chamber. Rarely, the valve is so deformed that it will not allow blood to flow easily in the normal direction (right atrium to right ventricle).
More commonly, these abnormalities cause the tricuspid valve to leak blood backwards into the right atrium when the right ventricle contracts. As a result, the right atrium becomes enlarged. If the tricuspid regurgitation (leak) is severe enough, congestive heart failure can result. If there is excessive backflow into the right atrium, the pressure within the right atrium becomes very high.
Normally, a fetus has a communication or hole between the right atrium and left atrium known as the foramen ovale or PFO. The PFO usually closes after birth. In Ebstein’s Anomaly, the high pressure in the right atrium keeps the PFO open. This connection allows unoxygenated ("blue") blood to flow from the right atrium, bypassing the lungs and going directly to the body. This will result in lower oxygen levels in the blood. This is why children with Ebstein’s anomaly may be blue or “cyanotic”, and have low oxygen saturation.
Ebstein's anomaly may occur with other heart lesions, such as:
In addition, many patients with Ebstein's anomaly have an extra conduction pathway in the heart (Wolff-Parkinson-White syndrome) leading to episodes of abnormal fast heart rate (supraventricular tachycardia.)
Ebstein's anomaly can range from very mild to very severe. Many patients with milder forms of Ebstein's anomaly do not have symptoms and are diagnosed due to the presence of a heart murmur. Abnormal or extra heart sounds may also be present on the physical examination.
Some babies and children have bluish discoloration to their lips and nail beds (cyanosis), due to the flow of blood from the right atrium to the left atrium. Children may complain that their heart races, skips a beat, “beats funny” or "hiccups". They may tire more easily than other children or become short of breath, particularly during play. In adolescents and young adults, the sensation of "heart skipping" (palpitations) or fast heart rate, shortness of breath, and chest pain may be the first symptoms. Growth and development are usually normal in patients with Ebstein's anomaly.
Severely affected babies are often critically ill at birth, with low oxygen saturations (cyanosis) and heart failure requiring intensive care.
A chest X-ray will be taken to judge the size of the heart, which may be quite enlarged. An echocardiogram is used to definitively diagnose Ebstein's anomaly and identify any accompanying heart defects. This test allows the pediatric cardiologist to determine the degree of valve displacement, the severity of valve leakage (insufficiency) or valve narrowing (stenosis), the size of the heart chambers, and if a patent (open) foramen ovale is present.
An electrocardiogram (ECG) records the heart's rhythm. If the child has complained about a racing heart and the answer is not found in this initial test, he/she may go home with a recorder which is used to try to capture the episodes of tachycardia (rapid heart rate). Your child may also have an exercise stress test performed to better assess his/her heart function during activity.
Certain patients with Ebstein's anomaly may require cardiac catheterization to fully define their cardiac anatomy and function.
Mild defects may require no specific treatment, only prophylaxis for bacterial endocarditis. Medical treatment is used to help children with congestive heart failure or abnormal heart rhythms. Surgery may be indicated, depending on a child's specific circumstances. Surgical repair or replacement of the tricuspid valve and closure of the formamen ovale or atrial septal defect may be recommended.
Abnormal accessory conduction pathways that allow fast heart rates (supraventricular tachycardia) to develop may be ablated (removed) using procedures in the catheterization laboratory.
Medical therapy for heart failure or arrhythmias is typically used in conjunction with planned surgical intervention. In very severe forms of Ebstein's anomaly, an operation may be required in the newborn period and the treatment strategy is more like that for children with single ventricle cardiac anomalies.
Without any treatment, the prognosis for Ebstein’s anomaly is poor. A 1971 study reported that only 50% of patients survived to 13 years of age. However, children treated only with medicines have excellent results and few complications. Children who have surgery also generally do well.