Ebstein Syndrome

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.

Congenital Tricuspid Dysplasia; Ebstein Anomaly; Ebstein Malformation. (Do not confuse with Epstein Syndrome.)

First described in 1866 by the German physician Wilhelm Ebstein.

Accounts for approximately 0.5% of all congenital heart defects (1:20,000-50,000 live births). No sexual predilection has been reported.

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.

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.

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.

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 (up to 20% of patients may have an accessory pathway), and supraventricular tachycardia secondary to atrial distention. Tachydysrhythmias worsen cardiac function and result in decreased cardiac output and increased right atrial pressure and right-to-left shunting with marked cyanosis.

Obtain an electrocardiogram in presence of a history of dysrhythmias. Effectiveness of the current treatment must be assessed. A preoperative echocardiogram should be obtained to define right and left ventricular function, degree of tricuspid regurgitation and/or stenosis, and extent of right-to-left shunting. Also assess cardiac function clinically. Check preoperative saturation or better consider obtaining arterial blood gas analysis.

The goals during anesthesia are to avoid tachyarrhythmias (decrease the time for ventricular filling), maintain (or re-establish) appropriate filling pressures and myocardial contractility, minimize PVR (avoid acidosis, hypercapnia, and hypoxemia) in order to reduce regurgitation and support forward flow, and reduce right-to-left shunting. Appropriate premedication assists in controlling preoperative heart rate increases; however, deep sedation may result in increased PVR and should be avoided. Careful placement of central venous catheters is required to avoid triggering tachydysrhythmias. Treat intraoperative supraventricular tachycardias aggressively (e.g., adenosine, cardioversion) because they may start a vicious circle. Massive atrial enlargement has been reported and may prolong the onset of action of intravenous drugs. Paradoxical emboli may occur because of right-to-left shunting, so special attention should be paid to prevent air bubbles or clots from entering the circulation.

Continue antidysrhythmic medication perioperatively. Minimize use of anesthetic agents with myocardial depressant effects. Avoid drugs that may induce tachycardia and trigger tachydysrhythmia (e.g., atropine).