Ebstein's anomaly

What is Ebstein’s anomaly?

First described by Wilhelm Ebstein in 1866, Ebstein’s anomaly is a malformation of the tricuspid valve and right ventricle characterised by:¹

• Adherence of the septal and posterior leaflets to the underlying myocardium.

• Downward (apical) displacement of the functional annulus.

• Dilation of the 'atrialised' portion of the right ventricle, with various degrees of hypertrophy and thinning of the wall.

• Redundancy, fenestrations and tethering of the anterior leaflet.

• Dilation of the right atrioventricular junction.

Prenatal diagnosis of the Ebstein malformation has allowed for improvements in immediate postnatal management.²

How common is Ebstein’s anomaly? (Epidemiology)

Ebstein's anomaly is rare, with an incidence of approximately 1 in 20,000.³

Risk factors

Most cases are sporadic. Studies have shown both genetic and environmental risk factors:¹

• The anomaly is more common in twins and in those with a family history of congenital heart disease.

• Environmental factors found in studies include maternal exposure to benzodiazepines. Maternal lithium therapy can (rarely) lead to Ebstein's anomaly in the baby.

Symptoms of Ebstein’s anomaly (presentation)^{4 5}

Ebstein's anomaly presents with a spectrum of congenital abnormalities of the tricuspid valve and the right ventricle. The very variable anatomy determines the clinical presentation ranging from asymptomatic to very severe.

• The abnormality of the tricuspid valve leads to tricuspid regurgitation. The degree of tricuspid regurgitation is variable, ranging from mild to severe regurgitation.

• Presentation is often between the ages of 10 and 30 years but it can present at various stages of life:
  

  • Fetal life: diagnosed incidentally by echocardiography.

  • Neonatal life and infancy: presents with cyanosis and/or severe heart failure. Symptoms presenting in infancy often improve as the pulmonary vascular resistance decreases.

  • Adult life: fatigue, exertional dyspnoea, cyanosis, tricuspid regurgitation and/or right heart failure and palpitations (arrhythmias are common).

• Additional associated anomalies include bicuspid aortic valves, pulmonary atresia or hypoplastic pulmonary artery, subaortic stenosis, coarctation of the aorta, mitral valve prolapse, accessory mitral valve tissue or muscle bands of the left ventricle, ventricular septal defects and pulmonary stenosis.¹

Symptoms

• Cyanosis: common and often due to associated atrial right-to-left shunt and/or severe heart failure. Cyanosis is often transient in neonatal life with recurrence in adult life but may appear for the first time in adult life. In adult life, cyanosis progressively worsens and may be transiently increased due to paroxysmal arrhythmias.

• Fatigue and dyspnoea: due to right ventricular failure and decreased left ventricular ejection fraction.

• Palpitations and sudden cardiac death: due to paroxysmal supraventricular tachycardia or fatal ventricular arrhythmias.

Signs

Signs are variable depending on the extent of the anomaly.

• Cyanosis and clubbing: variable degrees of cyanosis, and transient worsening with arrhythmias.

• Precordial asymmetry: usually left parasternal prominence and occasionally right parasternal prominence.

• Jugular venous pressure (JVP): may be normal due to a large, thin-walled right atrium, which can absorb the volume and pressure transmitted from the right ventricle through an incompetent tricuspid valve.

• Signs of right heart failure: ankle oedema, hepatomegaly and ascites. Large A and V waves in the JVP.

• Heart sounds: the first heart sound is widely split with a loud tricuspid component. The second sound is usually normal but may be widely split. The third and fourth heart sounds are often present, even in the absence of congestive heart failure.

• The pansystolic murmur of tricuspid regurgitation is best heard at the lower left parasternal area and sometimes at the apex.

Differential diagnosis

• Accessory pathway-mediated Wolff-Parkinson-White syndrome and supraventricular tachycardia (SVT).

• Cyanotic congenital heart diseases.

• Tricuspid valve dysplasia and prolapse.

• Arrhythmogenic right ventricular cardiomyopathy.

• Atrial septal defect.

• Cases of severe right heart failure.

• Transposition of the great vessels.

Investigations³

• CXR: may be normal or demonstrate cardiomegaly, decreased pulmonary vasculature, large right atrium.

• The ECG is abnormal in most patients with Ebstein's anomaly. There may be tall and broad P waves (right atrial enlargement) and complete or incomplete right bundle-branch block. The R waves in leads V1 and V2 are small. Bizarre abnormalities of the terminal QRS pattern may also be present.

• Echocardiogram: allows definitive diagnosis.

• Cardiac magnetic resonance imaging with gadolinium quantifies right ventricular volumes and tricuspid regurgitation.

• Electrophysiology studies: can delineate accessory conduction pathways. Right-sided pathways are more common and 50% of patients have multiple pathways.

Treatment and management of Ebstein’s anomaly

Medical management and observation is often recommended for asymptomatic patients and may be successful for many years. Tricuspid valve repair is the goal of operative intervention. Repair also typically includes RV plication, right atrial reduction, and atrial septal closure or subtotal closure. Postoperative functional assessments generally demonstrate an improvement or relative stability related to degree of RV enlargement, RV dysfunction, RV fractional area change, and tricuspid valve regurgitation.³

Medical

Non-surgical management of Ebstein's anomaly includes:

• Prevention of infective endocarditis.

• Management of heart failure.

• Treatment of arrhythmias.

Surgical

Increasingly the trend is for operative intervention early in the development of heart failure.⁶ Complete repair of Ebstein's anomaly in symptomatic neonates has been shown to be possible, with good survival and excellent functional status.⁷

In patients over 50 years of age with Ebstein's anomaly, surgery is associated with good long-term survival and improved functional status, although long-term survival might be improved by performing surgery earlier.⁸

• Tricuspid valve repair is preferred over valve replacement. Bioprosthetic valves are preferred over mechanical prosthetic valves.

• Both the atrialised portion of the right ventricle and the very dilated, thin-walled right atrium can be resected.

• Associated heart abnormalities:
  

  • Correction of any associated intra-cardiac defects.

  • Associated septal defects may be closed.

  • Surgical treatment of associated arrhythmias.

• Palliative procedures: are usually reserved for severely ill infants with an otherwise poor prognosis. These include:
  

  • Creation of atrial septal defect.

  • Closure of tricuspid valve with plication of the right atrium.

  • Maintenance of pulmonary blood flow through an aorto-pulmonary shunt.

• Heart transplantation is appropriate in selected patients.

Complications of Ebstein’s anomaly

• Right heart failure.

• Infective endocarditis.

• Paradoxical embolism (passage of thrombus from venous system to arterial system via a septal heart defect); stroke and transient ischaemic attacks.

• Brain abscess due to right-to-left shunt.

• Sudden cardiac death.

Prognosis

• The prognosis depends on severity of the anomaly, degree of tricuspid regurgitation, degree of heart failure, associated anatomical defects and associated arrhythmias. People who survive into adulthood usually have milder forms of the anomaly with a better prognosis. Fewer than 5% of patients survive beyond the age of 50 years without surgery.⁹

• Fetal and neonatal presentation in Ebstein's anomaly is predicted to have a poor overall prognosis as the age at presentation is dependent on the severity of anatomical and haemodynamic derangements.¹⁰

• In utero presentation with fetal hydrops and neonates with cardiomegaly, congestive heart failure and cyanosis have a particularly poor outcome.¹⁰

• However, the overall prognosis for neonatal Ebstein's anomaly has improved with modern surgical techniques.^{11 12}

• Pregnancy is usually well tolerated in patients with Ebstein's anomaly.¹³

• In rare cases, patients with Ebstein's anomaly have lived for more than 70 years.¹