Ebstein’s Anomaly: From Fetus to Adult-Literature Review and Pathway for Patient Care.
Ramcharan TKW, Goff DA, Greenleaf CE, Shebani SO, Salazar JD, Corno AF.Pediatr Cardiol. 2022 Apr 23. doi: 10.1007/s00246-022-02908-x. Online ahead of print.PMID: 35460366 Review.
This review article aims to cover the pathophysiology of Ebstein’s anomaly including the varying severity and the associated structural, electrical and functional issues with thorough discussion of management. Throughout the article, sections are divided into fetal, neonatal, older children, adolescents and adults.
Commentary by Dr. Helen Parry (Leeds, UK), section editor of ACHD Journal Watch:
Introduction:
This section sets out the aim of the review
Anatomical definition:
The authors clearly state the hallmark of Ebstein’s anomaly is inferior displacement of the hinge-points of the septal and mural leaflets of the tricuspid valve into the right ventricle. This is due to failure of delamination of the leaflets and they usually form a combined leaflet. The valve annulus and functional orifice are rotationally displaced inferiorly to a varying extent.
Epidemiology and Etiology:
- 0.3-0.5% of congenital heart defects
- 40% of all tricuspid valve abnormalities
Associated abnormalities
Structural Cardiac Abnormalities
- Pulmonary stenosis, up to and including pulmonary atresia
- Interatrial communication in >90%, +/- associated cyanosis
- Prominent Eustachian valve
- Tetralogy of Fallot
- Isolated ventricular septal defect
- Congenitally corrected transposition of the great arteries
- Abnormal left ventricle up to 39% (abnormal myocardial function, septal motion, non-compaction)
- RV fibrosis
- Mitral valve abnormalities
Arrhythmia
SVT, usually AVRT, accounts for 75% and is caused by a combination of discontinuity between the central fibrous body and septal atrioventricular ring and dilatation of the RA.
There is a higher incidence of ventricular arrhythmia following surgery, possible due to ventriculotomy scar.
Extracardiac associations
These are mainly due to the space taken up by the dilated right heart and hypoperfusion of other organs
Genetics
Very few cases of Ebstein’s anomaly are inherited.
Presentation
Fetal
Detection depends on severity
The most severe forms are associated with early in utero death
Neonatal
Only the more severe forms present this early, generally developing cyanosis and heart failure in the first few days of life. Whilst the PDA is open and pulmonary vascular pressures are high, the small RV may not be able to generate high enough pressures to open the pulmonary valve, creating functional pulmonary atresia. Closure of the PDA can both improve and worsen symptoms
Adolescent/ Adult
Presentations include:
Incidental murmur
- Palpitations (40% from adolescence)
- Chest X ray done for another reason
- Cyanosis, particularly on exercise
Older adults may present with cyanosis due to increased stiffness of the RV and bi-directional shunting across the ASD. They may also present with heart failure.
Older patients with Ebstein’s anomaly may struggle during exercise due to:
- Inability to increase the RV output
- Further dilatation of the right heart due to increased systemic venous return, further displacing the septum and reducing LV function
- Increased right to left shunt
Natural History
Neonatal presentation 18% babies die in the first 28 days of life, 30% die before age 10 years and median mortality is 20 years
Late effects include right heart failure, LV dysfunction, arrhythmia, endocarditis
Diagnostic Investigations
The mainstay of fetal investigation is fetal echocardiography
Post natally (some of these investigations are obviously only appropriate in older children and adults):
- ECG
- CXR
- TTE
- TOE
- Holter monitor
- +/- cardiac catheter
- Cardiac MRI
- CPET
- EPS
Particular focus is given to the degree of apical displacement of the septal leaflet. >=15mm in children and >=20mm in adults is diagnostic. The Great Ormond Street Equation based on RA to LV+LA+RV ratio is also referred to but the clinical significance is not clear
Similarly, the Carpentier classification is detailed
Holter monitors may be particularly useful in picking up pre-excitation. The 70 year risk of sudden cardiac death is 15%.
MRI may be useful in patients with poor echo windows and is the gold standard for right heart volumes.
Management
Indications for surgery include
- Critically ill symptomatic neonates despite intensive medical management
- Severe or progressive cyanosis
- Progressive right heart dilatation
- Congestive heart failure
- Deteriorating systolic function
- RV outflow tract obstruction
- Decreasing or severe limitation (NYHA 3-4)
- Paradoxical embolus
- Recurrent or intractable life-threatening arrhythmia
Specific comments about different age groups:
Fetal-
Some institutions advocate increased surveillance after 32 weeks
Neonates-
Generally improve as pulmonary vascular resistance drops
Surgical management has higher mortality in neonates than any other age group. Careful assessment for univentricular or biventricular repair should attempt biventricular repair if possible
Infancy-
Anti-arrhythmic dugs as needed
Surgical approach (see below)
Adolescence and adults-
Anti-arrhythmic therapy, consideration of ICD
Cardiac catheterisation may be beneficial for evaluation of pulmonary vascular resistance pre operatively, or for device closure of the ASD
Surgery in adolescents and adults:
Guidance suggests indicated for more than moderate TR and symptoms, including deterioration in CPET performance, asymptomatic but progressive RV dilatation, dysfunction or progressive cardiomegaly on chest radiograph.
Cardiac transplantation should be considered where there is no other good surgical option or severely impaired LV function.
Surgical techniques:
- Detailed discussion of techniques including more historical approaches is given. However, most centres would veer towards cone repair. The anterior and posterior leaflets are delaminated and the posterior leaflet free edge is rotated clockwise and sutured to the anterior leaflet free edge to create a new annulus. The atrialised RV was plicated and the new annulus constructed at the true morphological level. It is believed that this reduces the recurrence of TR.
- Outcomes of the cone repair show significant reduction in regurgitation, reduction in |RV size and lower mortality but with deterioration in RV function, due to the haemodynamics involved rather than deterioration being caused by the cone procedure.
- ASD closure is advocated but a fenestrated closure is favoured with small RV cavity/ poor RV function and high PVR.
- Glenn procedures may also be done at the time of repair to reduce preload on the poorly contracting RV allowing an aggressive repair strategy. This is described as a “one and a half” ventricle repair.
- Univentricular repair by over-sewing the tricuspid valve (Starnes) is not generally done outside the neonatal period.
Surgical ablation of accessory pathways and medical management of arrhythmia/ prevention of post op arrhythmia is also discussed.
Pregnancy
This section is short, mentioning fetal growth restriction in cyanosed women with up to 6% offspring having a form of congenital heart disease. Otherwise, pregnancy is well tolerated.
Conclusion
This is more a brief summing up statement than a conclusion
Positive aspects:
The section on associated cardiac abnormalities is excellent, particularly comprehensive.
The article usefully highlights the risk of sudden cardiac death due to arrhythmia
Less positive aspects
There is a clear description of classification systems used to assess severity but no detail of how this guides us clinically (See GOS equation and Carpentier grading)
The cone repair is explained without the use of diagrams, making it extremely difficult to visualise
The difficulty of assessing RV function when it is flattered by TR is not highlighted
