Ebsteins anomaly of the tricuspid valve overview

Ebstein’s anomaly is a congenital heart defect in which the opening of the tricuspid valve is displaced towards the apex of the right ventricle of the heart (congenital apical displacement of the tricuspid valve that typically causes significant tricuspid regurgitation).

Ebstein anomaly was named after Wilhelm Ebstein, who in 1866 first described it the heart of a 19 year old patient Joseph Prescher.

The pathophysiology of Ebstein’s anomaly depends on the morphology of tricuspid valve and the right ventricle. The annulus of the valve is in normal position. The valve leaflets however, are to a varying degree attached to the walls and septum of the right ventricle. There is subsequent atrialization of a portion of the morphologic right ventricle (which is then contiguous with the right atrium). This causes the right atrium to be large and the anatomic right ventricle to be small in size. 50% of cases involve an atrial shunt (either a PFO or an ASD). Mutations in MYH7, which a sarcomere gene encoding the cardiac beta-myosin heavy chain have been linked in the occurence of familial Ebstein anomaly. Commonly associated conditions include Aortic coarctation, Cleft anterior leaflet of the mitral valve, Coarctation of the aorta, corrected transposition of the great arteries, Hypoplastic pulmonary arteries, Left ventricular outflow obstruction etc.

Lithium ingestion in first trimester of pregnancy, Benzodiazepine use by the mother,varnishing substances exposure.

Disorders that Ebstein’s anomaly must be distinguished from include Accessory pathway-mediated WPW syndrome and SVT,Atrial septal defect (ASD), Cyanotic congenital heart diseases, Isolated, severe tricuspid regurgitation, L-transposition of the great vessels, Severe right heart failure with dilation of the anulus.

Ebstein’s anomaly is a rare congenital heart disease (observed in 5/100,000 newborns in the United States) with no gender predilection, but a higher incidence in Caucasians.

Administration of lithium carbonate or benzodiazepines during pregnancy is associated with a higher risk of Ebstein’s anomaly.

The symptoms of Ebstein’s anomaly vary in severity, with some patients experiencing either no symptoms or very mild symptoms and others experiencing symptoms that may worsen over time such as (cyanosis), heart failure, heart block, or other tachyarrhythmias or bradyarrhythmias. Paradoxical embolization, brain abscesses and pulmonary embolism may also occur.

The symptoms of Ebstein’s anomaly depend upon the degree of apical displacement of the tricuspid valve leaflet as well as the degree of dysfunction of the tricuspid valve. If the tricuspid valve is severely deformed, fetal hydrops may occur. If the valve is functioning, patients may remain symptom free for many years.

• Exertional dyspnea
• Failure to grow
• Fatigue and cyanosis
• Heart failure
• Murmur
• Palpitations may occur secondary to SVTs (supraventricular tachycardia) and WPW (Wolff-Parkinson-White syndrome).
• Paradoxical embolization may cause brain abscesses (right to left shunting due to interatrial communication)

Ebstein’s anomaly is characterized by tricuspid regurgitation and variable degrees a cyanosis depending upon the magnitude of right to left shunting. And elevation of the jugular venous pressure is often present.

The EKG is abnormal in 50 to 60% of patients, and will often show signs of right atrial enlargement, including “Himalayan” P waves which are P waves greater than 2.5 mm in height in leads 2, 3, and aVF. First-degree AV block, low QRS voltage, an atypical right bundle branch block, T wave inversions, and Wolff-Parkinson-White syndrome may also be present.

The chest x-ray in Ebstein’s anomaly of the tricuspid valve may demonstrate cardiomegaly, a dilated right atrium and a pruned pulmonary vasculature.

Computed tomography can be helpful as a diagnostic tool in conditions where the echocardiographic findings are inconclusive.

Magnetic resonance imaging can be helpful as a diagnostic tool in conditions where the echocardiographic findings are inconclusive.^[1]

Electrophysiologic testing may be done in Ebstein’s anomaly patients who have rhythm disturbances such as tachyarrhythmias, or Wolff-Parkinson-White syndrome. An electrophysiology study helps in identifying accessory pathways prior to an ablation procedure.

Medical management of patients with Ebstein’s anomaly consists of supportive care such as:

• Control of the heart rhythm with antiarrhythmic drugs
• Inotropic agents and diuretics for heart failure
• Anticoagulation in patients with atrial fibrillation and paradoxical embolization

Some Ebstein’s anomaly patients present with an (antidromic) AV nodal reentrant tachycardia with associated pre-excitation. Among these patients, the preferred pharmacological treatment agent is procainamide. Since AV-blockade may promote conduction over the accessory pathway, drugs such as beta blockers, calcium channel blockers and digoxin are contraindicated.

If there is atrial fibrillation with pre-excitation, treatment options include procainamide, flecainide, propafenone, dofetilide and ibutilide since these medications slow conduction in the accessory pathway causing the tachycardia and should be administered before considering electrical cardioversion. Intravenous amiodarone may also convert atrial fibrillation and/or slow the ventricular response.

Tricuspid valve repair is indicated in patients in which there is symptoms or deteriorating exercise capacity, cyanosis (oxygen saturation less than 90%), paradoxical embolism, progressive cardiomegaly on chest x-ray or progressive right ventricular dilation or reduction of right ventricular systolic function. When possible, repair is favored over replacement.

In so far as lithium and benzodiazepines have been associated with an increased risk of Ebstein’s anomaly, these drugs should be avoided if possible in the first trimester of pregnancy.

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