Ebstein Anomaly/Tricuspid Dysplasia

Ebstein Anomaly:

• Failure of delamination and adherence of leaflets to underlying RV myocardium
• Less than 1% of congenital heart disease cases
• Males: females=1:1
• Associated with trisomy 13, 18 and 21
• If Ebstein anomaly is identified, karyotyping should be performed
• Frequently diagnosed in utero because of the associated cardiomegaly, hydrops and SVT

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Anatomy:

• Congenital malformation causing the posterior and septal leaflets to be displaced inferior towards the right ventricle inlet region
• Most commonly the septal leaflet is displaced
• Causes "Atrialization" of the right ventricle - a portion of the RV is now included with the RA because of the inferior displacement of the valve leaflets; large RA with a small RV inferior to the displaced leaflets
• The septal and posterior leaflets of the tricuspid valve are rudimentary and tethered
• Anterior leaflet of the tricuspid valve is normally placed and appears large and sail-like with shortened chordae
• The anterior leaflet usually delaminates completely and maintains its annular hinge at the normal atrioventricular junction
• Maternal lithium exposure is associated with Ebstein anomaly (lithium used to treat manic depressive psychosis)
• Atrial septal defect occurs in most Ebstein cases (right to left shunting=degree of cyanosis after birth)
• Functional right ventricular outflow obstruction (infundibular stenosis) is the most commonly associated type of pulmonary stenosis
• Functional pulmonary atresia is demonstrated due to the reduced force of contraction of the right ventricle, true pulmonary atresia can be seen also
• Prone to developing an arrhythmia, most commonly supraventricular tachycardia
• WPW syndrome is also common
• Associated with severe tricuspid regurgitation, severe right atrial enlargement, small right ventricle
• High velocity, holosystolic TR jet that typically originates from the middle of the right ventricle
• Right atrial dilation leads to hypoplastic lung
• Usually results in severe cardiomegaly, hydrops and tachyarrhythmias
• Can be mistaken for Uhl anomaly: right ventricle is very thin and has no myocytes, and cannot contract at all
• An imperforate tricuspid valve is present in a small number of cases of Ebstein anomaly; no flow detected across the TV with color or spectral Doppler; most severe form of the abnormality called imperforate Ebstein anomaly
• Prognosis is usually poor when diagnosed in utero

Associated with:

• ASD
• Right ventricular outflow obstruction
• VSD
• TOF
• Corrected transposition of the great arteries (left sided Ebstein)
• Left sided lesions - subaortic stenosis due to compression by the right ventricle, bicuspid AV, COA

Physiology:

• Right ventricle does not pump properly due to decreased flow through the tricuspid valve which causes functional pulmonary atresia
• The ductus arteriosus sends blood flow to the pulmonary artery
• Severe tricuspid regurgitation with right to left shunting across the atrial septal defect
• Cardiac output is maintained
• Restrictive interatrial shunting through the foramen ovale leads to fetal hydrops and demise
• Celermajer index: the ratio of the area of the right atrium and the atrialized right ventricle to the area of the functional right ventricle and the left ventricle = greater than 1.5 indicates poor prognosis after birth
  

Fetal Echo Findings:

• nlarged right atrium
• Measure the distance between the insertion point of the anterior leaflet of the mitral valve and the insertion point of the septal leaflet of the tricuspid valve
• Cardiothoracic ratio is increased (>0.45)
• Hallmark characteristic: tricuspid valves are dysplastic and tethered, resulting in right atrial dilatation and valve incompetence
• To-and-fro flow through the normal annular location at the level of the AV groove
• Dysplasia of the leaflets is best seen on the subcostal 4 chamber view
• Assess location of the origin of the tricuspid regurgitation and use PW Doppler to assess severity
• Tricuspid regurgitation is nearly always present and originates from mid right ventricle
• Severe levocardia is also common because of the enlarged right atrium
• Strong association with pulmonary stenosis or atresia
• May see bowing of the ventricular septum and compression of the left ventricle
• Atrial septal defect: right to left shunt (normal in fetal circulation)
• Ductus arteriosus: left to right (abnormal in fetal circulation)
• Increased A-wave reversal in IVC, ductus venosus and umbilical vein pulsatility
• Progressive cardiomegaly is a common complication with valvular regurgitation
• Serial measurement of: TV annulus, TR peak velocity, flow across pulmonary valve, pulmonary regurgitation, evaluation of LV function
• Serial exams are performed to detect signs of progressive heart failure and the development of hydrops
• TR velocity, umbilical artery flow and MCA flow should be evaluated with spectral Doppler on serial exams to assess for hemodynamic changes (CHF) that can indicate poor postnatal outcomes
• If CHF develops, blood flow to the brain can be impacted and is demonstrated on serial MCA evaluations
• Poor cardiac function can impact placental blood flow and fetal oxygenation which can be demonstrated on serial umbilical artery evaluations

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Tricuspid Dysplasia:

• Normally placed (no displacement) tricuspid valve leaflets with redundant and nodular leaflets
• Differentiated from Ebstein anomaly by the location of the TV leaflet insertion points, origin point of the TR jet, lack of atrialized RV
• Dysplastic tricuspid valves increase right ventricular pressure and lead to poor right ventricular function
• NO atrialized right ventricle, right ventricular dilatation, severe right atrial enlargement
• Right ventricular outflow tract obstruction is common in the form of the pulmonary stenosis or atresia
• Cardiothoracic ratio is increased (>0.5=50-60%)
• Exhibit severe tricuspid regurgitation that originates from the level of the TV annulus (used to differentiate from Ebstein anomaly)

The questions below are reading comprehension questions intended to help evaluate your retention of the material presented on the page. To access our registry exam practice questions or the CME post test, please refer to your login instructions for information on accessing the dedicated testing site (if your subscription included exam access).

Test Question 1
What three complications of Ebstein anomaly increase the likelihood of diagnosis on fetal echo?

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Test Question 2
Which of the following correctly describes the tricuspid valve leaflets in Ebstein anomaly?

1. posterior leaflet located more superior in the right atrium
2. anterior leaflet is shortened and dysplastic
3. septal leaflet is displaced inferiorly toward the apex
4. all three leaflets are in abnormal locations in the right ventricle

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Test Question 3
What type of pulmonary stenosis is most commonly seen with Ebstein anomaly?

1. Valvular
2. Branch artery
3. Functional infundibular
4. Atherosclerotic

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Test Question 4
Define and describe the Celermajer index.

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Test Question 5
Which of the following correctly describes how to document Ebstein anomaly on fetal echo?

1. Obtain a 4 chamber view and document the distance between the insertion points of the MV and TV leaflets
2. Measure and calculate the C/T ratio
3. Document the origin of the tricuspid regurgitation and severity
4. All the above

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Test Question 6
What three Doppler findings should be evaluated on serial exams of a patient with Ebstein anomaly?

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Test Question 7
Why are serial exams performed on fetuses with Ebstein anomaly?

1. to detect progressing cardiomyopathy
2. to detect progressing congestive heart failure
3. to detect clot formation in the small RV
4. to detect growth restriction

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Test Question 8
How can Ebstein anomaly and tricuspid dysplasia be differentiated on fetal echo?

1. document valve leaflet motion
2. document valve leaflet number
3. document valve leaflet insertion points
4. document RV function

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