Background
Ebstein anomaly is a congenital malformation of the heart that is characterized by apical displacement of the septal and posterior tricuspid valve leaflets, leading to atrialization of the right ventricle with a variable degree of malformation and displacement of the anterior leaflet.
Wilhelm Ebstein first described a patient with cardiac defects typical of Ebstein anomaly in 1866. In 1927, Alfred Arnstein suggested the name Ebstein's anomaly for these defects. In 1937, Yates and Shapiro described the first case of the anomaly with associated radiographic and electrocardiographic data.
Pathophysiology
The embryological development of tricuspid valve leaflets and chordae involves undermining of the right ventricular free wall. This process continues to the level of the atrioventricular (AV) junction. In Ebstein anomaly, this process of undermining is incomplete and falls short of reaching the level of the AV junction. In addition, the apical portions of the valve tissue, which normally undergo resorption, fail to resorb completely. This results in distortion and displacement of the tricuspid valve leaflets, and a part of the right ventricle becomes atrialized. In one study involving 50 hearts with the anomaly, the entire right ventricle was found to be morphologically abnormal.[1]
Ebstein anomaly is commonly associated with other congenital, structural, or conduction system disease, including intracardiac shunts, valvular lesions, and accessory conduction pathways (eg, Wolff-Parkinson-White [WPW] syndrome).
The hemodynamic consequences of Ebstein anomaly result from displaced and malformed tricuspid leaflets and atrialization of the right ventricle. The leaflet anomaly leads to tricuspid regurgitation. The severity of regurgitation depends on the extent of leaflet displacement, ranging from mild regurgitation with minimally displaced tricuspid leaflets to severe regurgitation with extreme displacement.
The atrialized portion of the right ventricle, although anatomically part of the right atrium, contracts and relaxes with the right ventricle. This discordant contraction leads to stagnation of blood in the right atrium. During ventricular systole, the atrialized part of the right ventricle contracts with the rest of the right ventricle, which causes a backward flow of blood into the right atrium, accentuating the effects of tricuspid regurgitation.
Epidemiology
Frequency
United States
True prevalence is unknown because mild forms frequently are undiagnosed. Currently, with wide application of echocardiography, more cases are being diagnosed. Ebstein anomaly probably accounts for 0.5% of cases of congenital heart diseases.
Mortality/Morbidity
The natural course of the disease varies according to the severity of tricuspid valve displacement.
- Patients presenting in infancy generally have severe disease and unfavorable prognosis.[2, 3]
- Mean age of presentation is in the middle teenage years. According to older observational data, approximately 5% of these patients survive beyond age 50 years. The oldest recorded patient lived to age 85 years.
Race
Ebstein anomaly is more common in children of white females.
Sex
No specific sex predominance exists.
Age
Ebstein anomaly can present at various stages of life.
- Fetal life: Ebstein anomaly is usually diagnosed incidentally by echocardiography.
- Neonatal life and infancy: Ebstein anomaly presents with cyanosis and/or severe heart failure; typically, symptoms present in infancy improve as pulmonary vascular resistance decreases.
- Adult life: Ebstein anomaly presents with fatigue, exertional dyspnea, cyanosis, tricuspid regurgitation and/or right heart failure, and palpitations; arrhythmias are common.
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