What is an Ebstein 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 right atrial enlargement. 1, 2

Definition and Epidemiology

• Ebstein's anomaly is defined as a congenital malformation of the tricuspid valve and right ventricle characterized by downward (apical) displacement of the functional annulus, usually involving the septal and inferior (posterior) leaflets 3
• It accounts for approximately 0.5-1% of all congenital heart defects, with a birth prevalence of about 0.005% (1 in 20,000 live births) 1, 4
• Maternal exposure to lithium or benzodiazepines during pregnancy has been associated with increased risk of Ebstein's anomaly 5

Anatomical Features

• Key anatomical abnormalities include:
  • Apical displacement of the septal and posterior leaflets of the tricuspid valve below the atrioventricular junction 2
  • Adherence of the tricuspid valve leaflets to the underlying myocardium (failure of delamination) 2
  • Atrialization and dilation of the inflow portion of the right ventricle 1, 2
  • Redundancy, tethering, and fenestrations of the anterior tricuspid valve leaflet 2
  • Varying degrees of tricuspid regurgitation (rarely stenosis) 2, 6
  • Enlargement of the right atrium 2

Associated Cardiac Abnormalities

• More than 50% of patients have a shunt at the atrial level (patent foramen ovale or secundum atrial septal defect), resulting in varying degrees of cyanosis 2
• Approximately 25% of patients have one or more accessory conduction pathways, increasing the risk of atrial tachycardias 2
• Other common associated abnormalities include:
  • Ventricular septal defects 2
  • Varying degrees of right ventricular outflow tract obstruction 2
  • Mitral valve prolapse 2
  • Abnormalities of left ventricular morphology and function 2

Clinical Presentation

• The clinical presentation varies widely in severity depending on the anatomical abnormalities 1, 2:
  • Neonates may present with cardiomegaly, congestive heart failure, and cyanosis 1
  • Children and adults commonly present with:
    • Exercise intolerance and dyspnea 2
    • Fatigue 2
    • Symptomatic arrhythmias 2
    • Right-sided heart failure 2
    • Cyanosis (when atrial shunt is present) 2
    • Risk of paradoxical embolism resulting in transient ischemic attack, stroke, or cerebral abscess 2
  • Some patients may remain asymptomatic into adulthood 1, 7

Diagnostic Evaluation

• Electrocardiogram findings include tall peaked P waves ("Himalayan P waves"), QR pattern in lead V1, and prolonged "splintered" QRS with right bundle-branch block pattern 2
• Chest X-ray may show severe cardiac enlargement with right atrial prominence, "globular" cardiac contour, and clear lung fields 2
• Echocardiography is the primary diagnostic tool to confirm diagnosis 2
• Cardiovascular magnetic resonance (CMR) is useful for determining anatomy, right ventricular dimensions, and systolic function 1, 2
• Transesophageal echocardiography (TEE) is useful for surgical planning when transthoracic images are inadequate 2
• Electrophysiological study is recommended before surgical intervention, particularly with ventricular preexcitation 2

Management

• Surgical repair or reoperation is recommended for Ebstein's anomaly with significant tricuspid regurgitation when the following are present 1, 2:
  • Heart failure symptoms
  • Objective evidence of worsening exercise capacity
  • Progressive right ventricular systolic dysfunction
  • Progressive right ventricular enlargement
  • Systemic desaturation from right-to-left atrial shunt
  • Paradoxical embolism
  • Atrial tachyarrhythmias
• Electrophysiological interventions, such as catheter ablation, are recommended for patients with high-risk pathway conduction or multiple accessory pathways 1, 2

Prognosis

• Prognosis varies widely based on severity of the defect 1
• Poor prognostic factors include 1:
  • NYHA class III/IV symptoms
  • Cardiothoracic ratio >65%
  • Atrial fibrillation
• Ten-year survival is approximately 61% in patients presenting in the perinatal period 1

Follow-up and Monitoring

• All patients with Ebstein's anomaly should have regular follow-up at centers with expertise in adult congenital heart disease 1, 2
• Frequency of follow-up depends on disease severity 2:
  • Mild disease: cardiology visits every 12-24 months
  • Moderate disease: every 12 months
  • Severe disease: every 6-12 months
  • End-stage disease: every 3-6 months
• Follow-up should include ECG, echocardiography, CMR, exercise testing, and pulse oximetry as appropriate 1