Ebstein's Anomaly

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1. Morphology
A. Anatomical characterisitics
· The septal and posterior leaflets of the tricuspic valve are displaced inferiorly towards the RV apex
· The anterior leaflet is large and sail-like with abnormally numbered and placed chordal attachments
· The area of right ventricle between the true tricuspid annulus and the displaced attachment of the septal and posterior leaflets is thinned and dilated (atrialized)
· The remainder of the right ventricular cavity is small
· The valve leaflets may be adherent to the right ventricular wall
· The RV infundibulum can be obstructed by the anterior leaflet and/or its chordal attachments
· The conduction system follows its normal course
· The anomaly can be right or left-sided
· Left-sided lesions are usually in the setting of corrected TGA and have a morphologic right-sided valve

B. Carpentier's classification
· Type A = RV volume is adequate
· Type B = large atrialized segment of RV; mobile anterior leaflet
· Type C = restricted movement of anterior leaflet; may cause infundibulum obstruction
· Type D = near-complete atrialization of the RV (Uhl's syndrome)

C. Associated cardiac anomalies
· PFO or ASD most common
· Right ventricular outflow tract obstruction
· Wolfe-Parkinson-White syndrome

2. Clinical Presentation
A. Contributing factors
· Severity of tricuspid incompetence
· Presence of associated atrial septal defect
· Right ventricle impairment
· Other cardiac anomalies
· There is a broad range of symptom severity and age of presentation

B. Neonatal Presentation
· Worst deformity of valve and RV
· Tricuspid incompetence accentuated by normal elevated pulmonary resistance
· Associated pulmonary stenosis or atresia
· Pulmonary hypoplasia correlated with tricuspid valve incompetence

C. Other Features
· Right ventricular dysfunction
· Cardiomegaly, hepatomegaly, ascites, fluid retention
· Tricuspid valve incompetence
· Cyanosis
· Atrial level R to L shunt, polycythemia
· Paroxysmal tachycardia
· Wolff-Parkinson-White Syndrome
· Paradoxical embolus
· Cerebral abscess

D. Natural History
· Prognosis is poor with presentation during the first week of life
· Prognosis improved with presentation after infancy and with mild symptoms
· Exercise tolerance often reduced
· Failure to thrive
· CHF, sudden death, and paradoxical emboli are the three most common causes of death

3. Diagnosis
· Cyanosis indicates significant right-to-left shunting
· Palpitations are common
· Chest X-ray characteristically shows a globular heart from the enlarged right atrium
· MRI becoming more useful for calculating RV size and function
· 2-D echocardiography is diagnostic and accurately evaluates the following:

a) RA size

b) tricuspid annulus size

c) function of the valve leaflets

d) evidence of RVOTO

e) presence of PFO or ASD

f) degree of valve incompetence

4. Medical Management
· PGE for the neonate in extremis
· General supportive care of cyanotic infants
· All patients eventually show progressive deterioration and will become possible candidates for surgery

5. Indications for Operation
· Significant tricuspid valve incompetence
· Moderate to severe cyanosis with compensatory polycythemia
· Congestive heart failure (NYHA class III or IV)
· Extreme cardiomegaly
· Arrhythmias

6. Operative Technique
· Tricuspid valve repair is preferred and more likely when repaired early
· Replace the valve if unable to repair
· Plicate the atrialized right ventricle
· Close any associated ASD
· Consider Maze procedure for atrial arrythmias
· Interrupt accessory conduction pathways if present

7. Operative Modifications
A. Repair with tricuspid valve replacement
· Atrial plication
· The original operation replaced the tricuspid valve with a prosthetic ball valve
· Current valve replacement is usually done with a mechanical prosthetic valve

B. The Mayo (Danielson) annuloplasty
· Pledgets placed in ventricle and woven up to level of annulus
· Sutures tightened to eliminate atrialized portion and form a competent valve

C. Ring annuloplasty
· Remodels the shape of the annulus to improve valve competence

D. The Carpentier repair
· Mobilize behind the anterior leaflet and repair any fenestrations or perforations

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· Vertically plicate of the atrialized portion

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· This approach has less tension and reduces the diameter of the tricuspid annulus
· Advance the anterior leaflet across the plicated area to cover the orifice

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· Placement of an annular ring supports the repair

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E. The Quaegebeur repair
· Similar to Carpentier repair; annuloplasty ring is omitted

F. The Starnes operation
· Neonates in extremis may require urgent intervention
· The ASD is enlarged by excising all of the septum primum
· The tricuspid valve is closed with a pericardial patch
· The right atrium is plicated
· A systemic-pulmonary shunt is created
· If right ventricular function is inadequate, a Fontan operation may be necessary

8. Results
· Early (hospital) mortality is about 5%
· Acute heart failure is the principal cause of early mortality
· Late death is uncommon
· Consider bidirectional Glenn shunt in paitents with decreased RV function
· The tricuspid valve is usually competent or has mild incompetence long-term, with a low rate of reoperation (3-5%)
· Heart block is uncommon
· W-P-W cured with surgical interruption
· NYHA class is I or II in the majority of patients
· Exercise tolerance and oxygen uptake are improved on maximal exercise testing