Rush Center for Congenital
and Structural Heart Disease

Definition

 

The tricuspid valve is normally slightly displaced apically when compared to the mitral valve.  If this displacement is exaggerated, it will result in abnormal function of the tricuspid valve resulting in regurgitation and stenosis (Ebstein malformation of tricuspid valve).  Tricuspid regurgitation may be severe, resulting in significant dilation of the right atrium.  The portion of the right ventricle situated above the apically displaced tricuspid valve becomes thin due to exposure to low pressures.  This change in the right ventricle is called atrialization.

 

Incidence

 

Ebsteinís anomaly occur in 0.3-0.8% of all congenital heart diseases in the first year of life, 1:20,000-50,000 live births. There is equal male to female occurrence. There are some findings that may suggest a familial occurrence of this disease. Ebstein malformation of the tricuspid valve may be associated with VSD, ASD, AV canal defect, corrected transposition of the great arteries, pulmonary stenosis and pulmonary atresia. It is seen in patients with Down syndrome, Marfanís syndrome, Ulrich-Noonan syndrome and Cornelia de Lange.

Maternal lithium ingestion has been strongly related to Ebsteinís malformation.

Natural history:

Mortality in children presenting in the neonatal period is 30-50%. Mortality at all ages is 12.5%.

Mortality is higher with severe right atrial enlargement, large atrialized right ventricular portion, distally tethered tricuspid valve leaflet and right ventricular dysplasia. It is also noted that the mortality rate is higher in patients with other associated congenital heart diseases, when presentation is in infancy and with severe cyanosis or congestive heart failure.

 
 

 

 

Embryology

 

The right ventricle enlarges by a process known as undermining in which the muscular tissue under the tricuspid valveís endocardial tissue is resorbed with fibroblast infiltration of leaflets and remnant attachments (chordae). The anterior leaflet of the tricuspid valve form at an earlier embryological stage than the posterior and septal leaflet. Papillary muscles are myocardial bands that are not resorbed nor infiltrated by fibroblasts. Therefore, it is possible that an abnormal process of undermining of the right ventricle occurs during embryologic development leading to abnormal septal and posterior tricuspid valve leaflet formation.

 

 

Pathology

 

There is adherence of the posterior and septal leaflets to the myocardium with apical displacement of effective orifice. Anterior leaflet becomes redundant and fenestrated. The portion of the right ventricle that becomes incorporated into the right atrium because of the apical displacement of the tricuspid valve orifice become atrialized and the annulus of the tricuspid valve become dilated.

Normally, there is some apical displacement of the affected tricuspid valve orifice which should be less than .8 cm/M2 of the body surface area. In mild cases the tricuspid valve leaflets are normal appearing with only mild apical displacement. In moderate to severe cases the leaflets are thick, nodular and focally muscularized and attached to the underlying muscular wall. The chordae of the tricuspid valves are either very few or absent. In most severe cases the whole right ventricular inlet portion is atrialized.

 
 

 

 

Pathophysiology

 

The anterior tricuspid valve leaflet forms a large sail-like structure with or without fenestration and with or without blood flow obstruction. When there is no fenestration of the tricuspid valve leaflet it will result in tricuspid stenosis. Rarely is the anterior leaflet atretic. Tricuspid valve annulus is in normal location but dilated. The tricuspid valve forms an incomplete fibrous ring resulting in Wolf-Parkinson-White syndrome. In severe cases the inferior right ventricular wall is thin and void of muscle cells thus forming an aneurysmal structure. The right ventricle is dilated and the interventricular septum bulges leftward. This may cause episodic left ventricular outflow tract obstruction. The right atrium is dilated secondary to tricuspid valve anomalies and tricuspid insufficiency. The patent foramen ovale is almost always patent and is sometimes associated with a secundum ASD. Surgical plication of the tricuspid valve may cause kinking of the right coronary artery leading to infarction of the right ventricle and the left ventricular wall. The construction of the tricuspid valve into a competent valve may still not cause right ventricular dilatation to regress secondary to irreversible RV wall changes.

Differential diagnosis:

Uhlís anomaly:

In this anomaly there is thinning of the right ventricular wall, however, the tricuspid valve is normal though often is incompetent.

Right ventricular dysplasia:

This also has a normal tricuspid valve with excessive infiltration of the right ventricle.

Tricuspid valve dysplasia:

This anomaly is associated with an abnormal tricuspid valve leaflet but the attachment and location of the leaflets are normal.

Unguarded tricuspid valve orifice:

In this pathology there is no tricuspid valve tissue and is usually associated with pulmonary atresia.

Hypoplasia of the right ventricle apex is typically associated with a normal tricuspid valve.

Ebsteinís malformation could affect the left sided valve. This occurs with cardiac situs inversus and mirror image of the heart or this may occur in L-Transposition of the great arteries with the morphologic right ventricle on the left side and since the atrioventricular valves follow the ventricles they are associated with the tricuspid valve and will be left sided in this kind of anomaly and this may be affected by Ebsteinís anomaly. In such situations the tricuspid valve disease is typically not as severe as in cases of AV concordance and Ebsteinís malformation. Rarely, mitral valve Ebstein malformation may be noted and even more rarely both tricuspid and mitral valves are affected.

 

 

 

Clinical Manifestations

 

Patients may present with cyanosis, syncope, congestive heart failure, palpitation, sudden death and/or paradoxical embolization. The severity of the symptoms do not necessarily correlate with the severity of the pathological changes of the tricuspid valve.

On examination the patients will have malar flush, not correlating with cyanosis or polycythemia. Cyanosis and clubbing are common. There is sometimes deformed chest wall secondary to cardiomegaly. The precordium usually is quiet despite cardiomegaly. Systolic thrill is sometimes appreciated. There are normal neck veins even with severe TR secondary to a large compliant right atrium. The most striking finding is triple or quadruple rhythm secondary to added sounds which may result from a split S1 due to the delay in tricuspid valve closure. S2 is widely and persistently split secondary to right bundle branch block and delayed right ventricular semilunar valve closure. Also, ventricular filling sounds are present.

When Ebsteinís malformation is presented in the neonatal period it may be due to severe tricuspid valve regurgitation with severely dilated right atrium similar to pulmonary atresia with intact ventricular septum. On the other hand, it could present in a fashion similar to tricuspid atresia due to obstruction of the tricuspid valve.

During fetal life the tricuspid insufficiency if it is severe enough will cause severe dilatation of the right atrium which would hamper the normal growth of the lungs causing hypoplasia of the lungs. On the other hand, if the Ebsteinís malformation is mild and the right atrium does not dilate significantly soon after birth due to a drop in the pulmonary vascular resistance the clinical situation may improve.

 

 

 

ECG

 

Characteristic ECG findings include:

A large P wave, some studies suggest that a large P wave correlates with decreased oxygen saturation, severe symptoms and increased risk of death with or without pre-excitation.

Eighty-seven to ninety-seven per cent (87-97%) of patients initially present in normal sinus rhythm.

PR interval is prolonged in 16-42% of cases.

Right axis deviation is common in frontal plane axis.

Complete or incomplete right bundle branch block is seen in 77-94% of cases.

QRS morphology is abnormal with slurring, notching and low voltage due to paucity of right ventricular tissue and displacement of the left ventricle by a large right atrium.

Absent Q wave in V6 due to ventricular displacement secondary to a dilated right atrium.

Pre-excitation in 6-26% of patients in (WPW). WPW is seen in other types of congenital heart disease but of all of the WPW cases with congenital heart disease, one-third of them have Ebsteinís malformation.

WPW is usually of type B (RV free wall bypass tract). This will present as a positive delta wave in lead V6 giving the appearance of left bundle branch block.

Pre-excitation may not be easy to spot because of large P waves and delayed conduction in atrium causing prolonged PR interval and therefore attention should be paid to the delta wave rather than a short PR interval.

24-Hour Holter monitor is valuable in assessing arrhythmias not spotted on a 12-lead ECG.

Exercise testing is usually done for assessing function severity but is also helpful with exercise induced arrhythmia.

Electrophysiology:

Before echocardiography, diagnosis was done by obtaining RV electrical recording with right atrial pressure tracing during cardiac catheterization. However, cardiac catheterization is risky as it may lead to arrhythmia and therefore should be done cautiously.

In reciprocating a tachycardia the RP distance on surface ECG is prolonged due to delayed atrial conduction in almost all patients. Almost all bypass pathways are on the right side (free wall or septa), however, it is to the left side with corrected TGA in situs inversus with Ebsteinís malformation. Most supraventricular tachycardias are orthodromic. Electrophysiology study is indicated in patients with Ebsteinís malformation and arrhythmias.

Sudden death is encountered in 3-10% of patients and this is thought to be secondary to SVT leading to ventricular tachycardia or fast conduction of atrial fibrillation or flutter. Ebsteinís malformation cause 6% of all cases of sudden death with congenital heart disease which is a large percentage for such a rare anomaly.

Sudden death percentage increases after tricuspid valve annuloplasty.

 

  

 

 

CXR

 

The size of the heart varies and maybe anywhere from normal to severe cardiomegaly. Right atrial enlargement is the main cause of cardiomegaly and this may cause displacement of the left ventricle posteriorly. Pulmonary blood flow is decreased or within normal limits. If increased pulmonary blood flow is noted on an x-ray than this makes the diagnosis doubtful.

 

 

Echocardiography

 

This could assess the functional severity by the following observations:

The amount of right-to-left shunting at the atrial level.

Degree of tricuspid insufficiency (width of jet at origin and whether it goes to the hepatic veins).

Right and left ventricular dysfunction.

In addition, echocardiography can assess the potential response to surgery by assessing anatomy:

Displacement of septal leaflet.

Tethering of anterior leaflet.

Fenestration of anterior leaflet.

Leaflet dysplasia.

RV enlargement, aneurysm of right ventricular outflow tract.

When repairing tricuspid valve in Ebstein malformation it is important to have intraoperative echocardiography to assess success of such procedure. Residual insufficiency, RV function and tricuspid insufficiency through prosthetic valve if one is placed in could be assessed.

Right ventricular and left ventricular function should be monitored postoperatively in patients with plication of the tricuspid valve since right coronary artery may be kinked in the process of plication. Postoperative pericardial effusion is poorly tolerated in these patients and consequently should be closely monitored.

 
 

 

 

Cardiac Catheterization

 

Typically not required.  

 

 

Treatment

 

Surgical treatment of Ebsteinís malformation:

Valvuloplasty and RV reduction with ASD closure could be performed.

Tricuspid valve replacement with prosthesis would eliminate tricuspid insufficiency.

Preop electrophysiology for bypass pathways is necessary in order to perform intraop ablation.

Management of arrhythmias:

Since there is an increased rate of dysrhythmia preoperatively (SVT in 21% of the cases, ventricular tachycardia and ventricular fibrillation in 13% of cases, sinus bradycardia and pause in 23% of cases). Therefore, prophylactic Lidocaine intravenously for two days followed by treatment with Procainamide for three months may be helpful. However, effectiveness of such treatment is questionable.

Chronic atrial flutter is best treated with Digoxin in Class 1-A or Class 1-C patients. Digoxin should be started first since Class 1-A drugs are vagolytic and may cause 1:1 conduction of atrial flutter.

For refractory atrial flutter Class 3 treatment such as Amiodarone may be necessary. Some beta blockers are not effective.

In treating WPW beta blockers 1-A or 1-C agents could be utilized.

Ventricular arrhythmias could be treated with 1-A, 1-B or 3 (Amiodarone) could be used.

With decreased heart rate pacemaker is used.

Patients who require ventricular pacing should be done through epicardial leads rather intravenously since the tricuspid valve function is already compromised.

Ablating bypass pathways when repairing tricuspid valve is effective. Temporary postop atrioventricular wires are helpful in diagnosis and management.

 
 

 

 

Course and Prognosis

 

   

 

 

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