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Congenital tricuspid valve anomaly (deformation and
improper placement between the right atrium and right ventricle) resulting
in tricuspid insufficiency, which may present in the neonatal period as a
cyanotic heart disease but also may remain asymptomatic throughout life.
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Congenital Tricuspid Dysplasia; Ebstein Anomaly; Ebstein
Malformation. (Do not confuse with Epstein Syndrome.)
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First described in 1866 by the German physician Wilhelm
Ebstein.
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Accounts for approximately 0.5% of all congenital
heart defects (1:20,000-50,000 live births). No sexual predilection has
been reported.
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Sporadic in most cases. Lithium ingestion
during pregnancy has been strongly related to Ebstein syndrome. A few
familial cases with a possible autosomal recessive transmission have been
reported.
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The tricuspid annulus is displaced downward into
the right ventricle such that part of the right ventricle becomes
“atrialized” (i.e., lies above the valve). The anterior and septal valve
leaflets are affected the most and may be severely dysplastic, resulting in
tricuspid regurgitation. The distal ends of the valve leaflets may be fused,
resulting in a variant degree of tricuspid stenosis. The anterior leaflet may
obstruct the right ventricular outflow tract. Atrial septal defect (ASD) or enlarged patent foramen
ovale (PFO) is present in almost all cases. Most often, the tricuspid lesion
results in tricuspid insufficiency, but stenosis also is possible. Tricuspid
regurgitation causes distention of the atrium and the atrialized ventricular
portion, which is usually thin-walled with paradoxical movement during
ventricular systole. Even distention may be seen during atrial systole.
Because part of the right ventricle is atrialized, the functional right
ventricle is smaller than normal, and secondary dilatation may result in
thinning of the wall, predisposing to right ventricular failure. Forward
flow of blood is also affected by the fact that, during atrial contraction,
part of the blood from the right atrium is pumped into the atrialized
portion of the right ventricle causing its dilatation, whereas during
ventricular contraction the blood in the atrialized part is pushed back into
the (dilated) atrium. Right-to-left shunting occurs across the ASD or PFO,
leading to a variable degree of cyanosis. Cyanosis is thus a common feature
of this anomaly occurring in more than 50% of patients.
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Based on the clinical findings of cyanosis associated
with signs of tricuspid regurgitation. The chest radiograph shows
cardiomegaly with diminished pulmonary markings. A history of paroxysmal
supraventricular tachycardia is possible. The final diagnosis is confirmed
by echocardiography or magnetic resonance imaging.
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Neonates may often present with cyanosis, heart
failure, tricuspid regurgitation (with cannon v waves and pulsatile liver),
and right ventricular failure. These symptoms may improve once the initially
high pulmonary vascular resistance (PVR) decreases. Not uncommonly, cyanosis
recurs or exacerbates later in childhood secondary to right heart failure
with dilatation of the right heart. The clinical findings may include
episodic cyanosis, decreased exercise tolerance, and dysrhythmias in
combination with signs of tricuspid regurgitation. Electrocardiographic
findings include right bundle branch block, Wolff-Parkinson-White
syndrome-like pattern ...