What is Ebstein's anomaly?

Ebstein's Anomaly

Ebstein's anomaly is a rare congenital heart defect characterized by apical displacement of the tricuspid valve leaflets into the right ventricle, resulting in atrialization of the right ventricle, tricuspid regurgitation, and varying degrees of right ventricular dysfunction. 1

Anatomical Features

• Displacement of the tricuspid valve leaflets (particularly septal and posterior) toward the apex of the right ventricle 1
• Adherence of the tricuspid valve leaflets to the underlying myocardium (failure of delamination) 1
• Atrialization and dilation of the inflow portion of the right ventricle 1
• Redundancy, tethering, and fenestrations of the anterior tricuspid valve leaflet 1
• Varying degrees of tricuspid regurgitation 1
• Enlargement of the right atrium 1

Epidemiology

• Occurs in approximately 0.005% of live births (1 in 20,000) 1, 2
• Accounts for about 0.5-1% of all congenital heart defects 2
• May be associated with maternal lithium exposure during pregnancy 3

Associated Abnormalities

• Atrial septal defect or patent foramen ovale (>50% of patients) 1
• Accessory conduction pathways (approximately 25% of patients) 1
• Ventricular septal defect 1
• Right ventricular outflow tract obstruction 1
• Mitral valve prolapse 1
• Abnormalities of left ventricular morphology and function 1

Clinical Presentation

The clinical presentation varies widely depending on severity:

• Neonates: May present with cardiomegaly, congestive heart failure, and cyanosis; 20-40% will not survive beyond 1 month 1
• Children: May have progressive right-sided heart failure, but most reach adolescence and adulthood 1
• Adults: May be asymptomatic or present with exercise intolerance, dyspnea, fatigue, arrhythmias, and right-sided heart failure 1

Common Symptoms and Signs

• Exercise intolerance with dyspnea 1
• Fatigue 1
• Symptomatic arrhythmias 1
• Right-sided heart failure 1
• Cyanosis (if right-to-left shunting through ASD/PFO) 1
• Risk of paradoxical embolism (stroke, TIA, cerebral abscess) 1
• Holosystolic murmur at lower left sternal border that increases with inspiration 1
• Loud first heart sound and possible systolic clicks 1

Diagnostic Evaluation

Electrocardiogram

• Tall, peaked P waves ("Himalayan P waves") 1
• QR pattern in lead V1 (may extend to V4) 1
• Prolonged QRS duration with right bundle-branch block pattern 1
• Preexcitation (Wolff-Parkinson-White syndrome) may be present 1

Chest X-ray

• May be nearly normal in mild cases 1
• Right atrial enlargement with "globular" cardiac contour 1
• Clear lung fields 1
• Small great arteries 1

Echocardiography

• Primary diagnostic modality 1
• Transthoracic echocardiography (TTE) to evaluate tricuspid valve morphology and function 1
• Transesophageal echocardiography (TEE) useful for surgical planning if TTE images are inadequate 1

Cardiac Magnetic Resonance (CMR)

• Useful for determining anatomy, right ventricular dimensions, and systolic function 1
• Correlates well with intraoperative findings 1
• Recommended for baseline assessment with periodic follow-up 1

Electrophysiological Study

• Recommended before surgical intervention on the tricuspid valve 1
• Useful in evaluation of patients with ventricular preexcitation 1

Management

Indications for Surgical Intervention

Surgical repair or reoperation for Ebstein's anomaly with significant tricuspid regurgitation is recommended when one or more of the following are present:

• Heart failure symptoms 1
• Objective evidence of worsening exercise capacity 1
• Progressive right ventricular systolic dysfunction 1
• Progressive right ventricular enlargement 1
• Systemic desaturation from right-to-left atrial shunt 1
• Paradoxical embolism 1
• Atrial tachyarrhythmias 1

Electrophysiological Interventions

• Catheter ablation is recommended for patients with high-risk pathway conduction or multiple accessory pathways 1
• Electrophysiological study with or without catheter ablation is reasonable before surgical intervention 1

Surgical Approaches

• Tricuspid valve repair is preferred when feasible 4
• Bidirectional superior cavopulmonary (Glenn) anastomosis may be considered at time of repair when severe right ventricular dilation or dysfunction is present 1
• Bioprosthetic valve replacement if repair is not possible 4
• Heart transplantation for patients with associated left ventricular dysfunction 4

Follow-up and Monitoring

Regular follow-up at centers with expertise in adult congenital heart disease is essential, with frequency based on disease severity:

• Outpatient cardiology visits: Every 3-24 months depending on severity 1
• ECG: Every 12-24 months 1
• Echocardiography: Every 12-24 months 1
• CMR: Every 12-60 months depending on severity 1
• Exercise testing: Every 12-36 months 1
• Pulse oximetry: Every visit for symptomatic patients 1

Prognosis

• Varies widely based on severity 1
• Poor prognostic factors include NYHA class III/IV symptoms, cardiothoracic ratio >65%, and atrial fibrillation 1
• In patients presenting in the perinatal period, 10-year survival is approximately 61% 1
• Patients who reach adolescence and adulthood often have excellent outcomes 1

Special Considerations

• Pregnancy: Pre-pregnancy evaluation recommended; cyanotic patients may require surgical correction before pregnancy 5
• Exercise: Patients with mild anomalies and no right heart dilation can participate in sports; those with severe anomalies should avoid competitive sports 5
• Surgery: Evaluation by adult congenital heart specialists prior to cardiac or non-cardiac surgery 5