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, varying degrees of tricuspid regurgitation, and right atrial enlargement. 1

Anatomical Features

• Apical displacement of the septal and posterior leaflets of the tricuspid valve below the atrioventricular junction is the key defining feature 1
• Adherence of the tricuspid valve leaflets to the underlying myocardium (failure of delamination) is characteristic 1
• Atrialization and dilation of the inflow portion of the right ventricle occurs to varying degrees 1
• Redundancy, tethering, and fenestrations of the anterior tricuspid valve leaflet are often present 1
• Varying degrees of tricuspid regurgitation (rarely stenosis) are hallmarks of the condition 1
• Enlargement of the right atrium is a characteristic feature 1

Epidemiology

• Occurs in approximately 0.005% of live births (1 in 20,000) 1
• Accounts for about 0.5-1% of all congenital heart defects 2
• More common in mothers exposed to lithium or benzodiazepines during pregnancy 3

Associated 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 1
• Approximately 25% have one or more accessory conduction pathways, increasing the risk of atrial tachycardias 1
• Ventricular septal defects are common associated abnormalities 1
• Varying degrees of right ventricular outflow tract obstruction are often present 1
• Mitral valve prolapse and other left ventricular abnormalities may be present 1

Clinical Presentation

• Presentation varies widely in severity from asymptomatic adults to severely affected neonates 1
• Adults commonly present with: 1, 4
  • Exercise intolerance
  • Dyspnea
  • Fatigue
  • Symptomatic arrhythmias
  • Right-sided heart failure
  • Cyanosis (when atrial shunt is present)
• Risk of paradoxical embolism resulting in transient ischemic attack, stroke, or cerebral abscess 1

Diagnostic Evaluation

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

Management

• All patients should have regular follow-up in a center for congenital cardiology 1
• Frequency of follow-up depends on disease severity: 1
  • Physiological Stage A (mild): cardiology visits every 12-24 months
  • Physiological Stage B (moderate): every 12 months
  • Physiological Stage C (severe): every 6-12 months
  • Physiological Stage D (end-stage): every 3-6 months

Surgical Indications

• Surgical repair or reoperation is recommended when one or more of the following are present: 1
  • 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
• Catheter ablation is recommended for patients with high-risk pathway conduction or multiple accessory pathways 1

Prognosis

• Prognosis varies widely based on severity of the defect 4
• Poor prognostic factors include NYHA class III/IV symptoms, cardiothoracic ratio >65%, and atrial fibrillation 4
• 10-year survival is approximately 61% in patients presenting in the perinatal period 4

Special Considerations

• Pre-pregnancy evaluation should be considered in all patients 5
• For cyanotic patients, surgical correction must be considered before pregnancy due to maternal and fetal risks 5
• Most acyanotic patients can tolerate pregnancy with manageable or no complications 5
• Patients with mild anomalies and no right heart dilation can participate in sports, whereas those with severe anomalies are discouraged from competitive sports 5