Ebstein Anomaly

A congenital malformation of the tricuspid valve in which the septal and posterior leaflets are displaced toward the apex and are partly fused to the myocardium, creating an "atrialised" portion of the right ventricle, with a large, sail like anterior leaflet and tricuspid regurgitation. The right atrium is dilated. About 1% of congenital heart disease, roughly 1 per 200,000 live births.

• Displacement of the septal leaflet by 8 mm/m2 body surface area or more defines the anomaly. A patent foramen ovale or secundum atrial septal defect is present in 80 to 90%, allowing right to left shunting and cyanosis. Pulmonary stenosis or atresia, ventricular septal defect, and left ventricular non-compaction may coexist.
• Accessory atrioventricular pathways (Wolff-Parkinson-White syndrome) occur in about 15 to 30%, often multiple and right sided. Maternal lithium exposure has been linked to a small absolute increase in risk.
• Severity ranges from fetal hydrops and neonatal death to an incidental finding in adults. Neonates with severe disease have functional pulmonary atresia, because the right ventricle cannot open the pulmonary valve against high pulmonary resistance, and this often improves as resistance falls over the first weeks of life.
• Presenting early with severe disease carries high mortality; those who reach adulthood often have a good outlook with timely surgery.

• Neonates: cyanosis, a massively enlarged heart on chest X-ray, tricuspid regurgitation murmur, respiratory distress from lung compression, with improvement as pulmonary vascular resistance falls.
• Children and adults: exertional dyspnoea, fatigue, cyanosis (from right to left shunt across the atrial communication), palpitations from supraventricular tachycardia, atrial flutter or fibrillation, syncope, right heart failure, paradoxical embolism with stroke or brain abscess.
• Signs: widely split first heart sound with a loud tricuspid component ("sail sound"), triple or quadruple gallop, pansystolic murmur of tricuspid regurgitation, wide splitting of the second heart sound, prominent jugular venous pulse, hepatomegaly, clubbing.
• Differential diagnosis: pulmonary atresia with intact septum, tricuspid atresia, tricuspid regurgitation from other causes (rheumatic, carcinoid, endocarditis, trauma), right ventricular cardiomyopathy (including arrhythmogenic cardiomyopathy), Uhl anomaly, atrial septal defect, tetralogy of Fallot, and pericardial effusion.
• Complications: supraventricular and ventricular arrhythmias, sudden death (about 3 to 4%), right heart failure, paradoxical embolism, brain abscess, endocarditis, atrial thrombus, and cyanosis with polycythaemia.

• ECG: tall and broad P waves, prolonged PR interval, right bundle branch block with low voltage in the right precordial leads, and a delta wave with a short PR interval if an accessory pathway is present (a left bundle branch block pattern of pre-excitation suggests a right sided pathway).
• Chest X-ray: a globular "box shaped" heart in severe cases (cardiothoracic ratio greater than 0.65), oligaemic lungs.
• Echocardiography: apical displacement of the septal leaflet by 8 mm/m2 or more, sail like anterior leaflet, atrialised right ventricle, tricuspid regurgitation grade, right atrial size, atrial septal communication and shunt direction, pulmonary outflow, left ventricular function and compression. In neonates, a severity ratio of the combined area of the right atrium and atrialised right ventricle to the area of the functional right ventricle plus left heart: a ratio greater than about 1.5 predicts poor outcome.
• Cardiac MRI: right ventricular volume and function. Holter monitoring and electrophysiology testing for arrhythmia, and exercise testing with saturation for symptoms.
• Pulse oximetry at rest and on exercise (a fall of 5% or more is significant). Haemoglobin and iron indices.

• Neonatal management:
  • Prostaglandin E1 (alprostadil) 0.01 to 0.05 micrograms/kg/min IV for the ductus dependent pulmonary circulation until pulmonary vascular resistance falls (usually days to a few weeks), with ventilation if needed.
  • Lower pulmonary vascular resistance with inhaled nitric oxide 20 ppm, oxygen, and mild hyperventilation to help forward flow; avoid inotropes that raise resistance.
  • Severe disease unresponsive to medical measures: surgery in the neonatal period. Options: a Starnes procedure (patch closure of the tricuspid valve, enlargement of the atrial septal defect, and systemic to pulmonary shunt) followed by single ventricle palliation; or neonatal tricuspid valve repair.
• Indications for intervention in children and adults:
  • Symptoms (heart failure, exercise intolerance, functional class III or IV (breathless on minimal exertion)), cyanosis with resting oxygen saturation less than 90%, paradoxical embolism, progressive right ventricular dilatation or dysfunction, cardiothoracic ratio greater than 0.65, and atrial arrhythmia.
• Surgery:
  • Tricuspid valve repair (cone reconstruction, which re-attaches the leaflets at the annulus) is the preferred technique when the anterior leaflet is mobile. Valve replacement with a bioprosthesis is used when repair is not possible.
  • Concomitant atrial septal defect closure is done when the right ventricle is able to cope; leave a fenestration (or partial closure) when right ventricular function is poor, to decompress the right side. One and a half ventricle repair (a bidirectional cavopulmonary shunt added to repair) for poor right ventricular function.
  • Surgical ablation (right sided maze) and accessory pathway division at surgery.
  • Operative mortality about 2 to 6% in experienced centres; reoperation is needed in 10 to 20% over 10 to 20 years.
• Arrhythmia management:
  • Supraventricular tachycardia with a regular narrow complex: vagal manoeuvres, then adenosine 6 mg rapid IV push, then 12 mg (adult); 0.1 mg/kg in children, maximum first dose 6 mg.
  • Atrial fibrillation or flutter with pre-excitation: avoid AV nodal blocking drugs (adenosine, verapamil, digoxin, beta blockers), since they can speed conduction through the accessory pathway; if unstable, give synchronised cardioversion at 100 to 200 J biphasic; if stable, give procainamide 15 to 17 mg/kg IV at 20 to 50 mg/min with blood pressure monitoring.
  • Catheter ablation of accessory pathways before surgery or when symptomatic, in a specialist centre (multiple pathways and difficult anatomy mean recurrence of about 10 to 20%).
  • Long term rate control in patients without pre-excitation: bisoprolol 2.5 to 10 mg daily, or digoxin 0.0625 to 0.25 mg daily. Rhythm control with sotalol 80 to 160 mg twice daily or amiodarone 200 mg daily after a loading period.
  • Anticoagulation for atrial fibrillation, flutter, or paradoxical embolism: warfarin to INR 2.0 to 3.0, or apixaban 5 mg twice daily (2.5 mg twice daily if two of age 80 or more, weight 60 kg or less, creatinine 133 micromol/L or more).
• Heart failure: furosemide 20 to 80 mg daily, spironolactone 25 to 50 mg daily; avoid vasodilators that lower systemic pressure and increase right to left shunting.
• Endocarditis prophylaxis after valve replacement or repair with prosthetic material, or for previous endocarditis or unrepaired cyanotic disease: amoxicillin 2 g orally (50 mg/kg in children) 30 to 60 minutes before dental procedures; azithromycin or clarithromycin 500 mg (15 mg/kg in children) if allergic to penicillin (clindamycin is no longer recommended).
• Special groups:
  • Pregnancy: usually tolerated if mild, with no cyanosis, normal right ventricular function and no arrhythmia; cyanosis (saturation less than 85%), heart failure or arrhythmia raise maternal and fetal risk (miscarriage, preterm birth, low birth weight); stop lithium in women planning pregnancy where mental health allows.
  • Children: observe mild disease; neonatal intervention only for severe cyanosis or duct dependent circulation; avoid contact sports with arrhythmia.
  • Cyanotic adults: avoid dehydration, use air filters on IV lines, and treat iron deficiency.
• Red flags: syncope, palpitations with wide complex tachycardia, rapid atrial fibrillation with pre-excitation, stroke or transient ischaemic attack, fever with murmur, worsening cyanosis.
• Follow up: every 6 to 12 months in mild disease with ECG, echocardiography, and Holter monitoring; every 3 to 6 months after surgery in the first year, then yearly, with lifelong specialist follow up.