Ebstein anomaly is a rare congenital cardiac defect that consists of variable apical displacement from the annulus and dysplasia of the septal and inferior leaflets of the tricuspid valve. The anterior leaflet always has a normal annular insertion, but is often dysplastic with abnormal distal attachments. This anomaly results in a portion of the right ventricle functioning as an atrium, with resulting decrease in the functional right ventricular volume. A wide variety of adverse hemodynamic sequelae may occur related to tricuspid valve dysfunction, right ventricular failure, cyanosis due to atrial shunting, and arrhythmias. There is a wide spectrum of manifestations depending on the age at presentation. Diagnosis is with ECG and imaging. Treatment is with medications and surgery, and sometimes with interventional catheterization.
(See also Overview of Congenital Cardiovascular Anomalies.)
Pathophysiology of Ebstein Anomaly
congenitally corrected transposition of the great arteries.
Ebstein anomaly is associated with abnormalities that commonly include severe dysplasia and variable dysfunction of the tricuspid valve leaflets, atrial septal defect, pulmonic stenosis, and Wolff-Parkinson-White syndrome. Multiple factors may lead to enlargement of the right atrium and elevated right atrial pressure, such as "atrialized ventricle," tricuspid regurgitation and/or stenosis, abnormal diastolic function, and limited capacity of the effective right ventricle distal to the tricuspid valve origin. Right atrial pressure will often exceed pressure in the left atrium and lead to right-to-left shunting through a patent foramen ovale or atrial septal defect and subsequent cyanosis. In very severe forms of the anomaly, during the newborn period, the right ventricle might not be able to generate a systolic pressure greater than the elevated pulmonary artery pressure, leading to "functional pulmonary atresia" (failure of a normal pulmonary valve to open in systole).
Symptoms and Signs of Ebstein Anomaly
There is a remarkably wide spectrum of manifestations, ranging from severe cyanosis in neonates, cardiomegaly, mild cyanosis in childhood, exercise intolerance in adolescents, to atrial arrhythmias or paroxysmal supraventricular tachycardia in a previously asymptomatic adult.
The onset of symptoms depends on the degree of tricuspid valve anatomic and functional derangement and presence of accessory pathways (eg, Wolff-Parkinson-White syndrome).
Clinical signs include a widely split first heart sound (S1) due to delayed closure of the anterior leaflet of the tricuspid valve producing a "sail sound" (a complex closing sound which includes a sudden stopping sound after the anterior and/or other tricuspid leaflets balloon out at systole). Multiple other auscultatory findings are often present, such as a systolic murmur due to tricuspid regurgitation, a diastolic murmur due to tricuspid stenosis, and third or fourth heart sounds due to abnormal right ventricular diastolic compliance. Patients may have elevated jugular venous pressure, chronic cyanosis, and clubbing.
Diagnosis of Ebstein Anomaly
Chest x-ray and ECG
Echocardiography
MRI
The ECG is usually abnormal with right axis deviation, low voltage right bundle branch block, and first-degree atrioventricular block. Wolff-Parkinson-White (WPW) syndrome is present in 20% of patients.
Chest x-ray findings include a variable degree of cardiomegaly with prominent right atrial borders. A subset of infants with severe Ebstein anomaly have massive cardiomegaly, referred to as a wall-to-wall heart shadow.
Echocardiography clearly delineates the anatomic and functional abnormalities of the tricuspid valve and any associated defects.
MRI provides valuable additional detail regarding the tricuspid valve, which is helpful in planning surgical intervention.
Treatment of Ebstein Anomaly
Medications
Surgery
Interventional catheterization
Medications play a role in managing neonates who are severely cyanotic and have inadequate pulmonary blood flow. Maintaining ductal patency with prostaglandins allows time for the pulmonary vascular resistance to drop. The decrease in pulmonary artery pressure allows the compromised right ventricle to provide adequate pulmonary blood flow. Some neonates with very severe Ebstein anomaly and functional compromise of the right ventricle require more prolonged palliation with a Blalock–Thomas–Taussig (BTT) shunt or other complex surgical interventions.
After the first several months of age, surgical repair of the tricuspid valve should be considered when any symptoms are present or there is evidence of progressive tricuspid valve dysfunction or enlargement of the right heart chambers. Surgical treatment of this anomaly has evolved over the years with developments such as the cone procedure (1). This approach to repair of the tricuspid vale involves delamination and mobilization of the tricuspid valve leaflets, plicating the atrialized portion of the right ventricle and the annulus and reattaching newly created "leaflet cone" to the true tricuspid annulus. These advances have greatly enhanced the surgeon's ability to achieve an excellent functional repair of even the most deformed tricuspid valves. Any atrial defect is closed at the same time.
Interventional catheterization techniques may be used to close an atrial communication when cyanosis is present, but the tricuspid valve dysfunction is only modest.
Treatment reference
1. da Silva JP, Baumgratz JF, da Fonseca L, et al: The cone reconstruction of the tricuspid valve in Ebstein's anomaly. The operation: early and midterm results. J Thorac Cardiovasc Surg133(1):215–223, 2007. doi:10.1016/j.jtcvs.2006.09.018
More Information
The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
American Heart Association: Common Heart Defects: Provides overview of common congenital heart defects for parents and caregivers
American Heart Association: Infective Endocarditis: Provides an overview of infective endocarditis, including summarizing prophylactic antibiotic use, for patients and caregivers
