Congenital tricuspid valve displacement, also known as Ebstein's anomaly, is a rare congenital heart defect.
Pathological Anatomy
The primary abnormality in this condition is the malformation of the tricuspid valve leaflets and their attachment points. The downward displacement of the tricuspid valve divides the right ventricle into a smaller functional right ventricle (comprising the muscular portion and the outflow tract) and an atrialized portion of the right ventricle, which, together with the original right atrium, forms an enlarged atrial chamber.
Pathophysiology
The main pathophysiological feature is tricuspid regurgitation, leading to increased right atrial pressure. If an atrial septal defect is present, right-to-left shunting may occur, resulting in cyanosis.
Clinical Manifestations
Symptoms vary in severity and may include palpitations, dyspnea, fatigue, dizziness, and signs of right heart failure. Approximately 80% of patients present with cyanosis, and 20% have a history of paroxysmal atrioventricular reentrant tachycardia.
The most prominent physical findings include:
- Marked cardiac enlargement
- Weak precordial pulsations
- Auscultation revealing a quadruple rhythm
- A holosystolic murmur of tricuspid regurgitation heard at the lower left sternal border
- Jugular venous distension with pulsations and hepatomegaly with pulsation
Auxiliary Examinations
Electrocardiography (ECG)
Common findings include first-degree atrioventricular block, tall and peaked P waves, and right bundle branch block. About 25% of patients exhibit Wolff-Parkinson-White syndrome (right-sided atrioventricular accessory pathway).
Chest X-ray
A characteristic finding is a globular, massively enlarged cardiac silhouette.
Echocardiography
This is of major diagnostic value, showing a downward displacement of the tricuspid valve, an enlarged right atrium, an atrialized right ventricle, and a relatively small functional right ventricle. Atrial septal defects can also be visualized.
For patients being considered for surgical treatment, right heart catheterization is recommended.
Diagnosis and Differential Diagnosis
Diagnosis is based on clinical presentation and echocardiographic findings.
In cyanotic patients, differentiation from other cyanotic congenital heart diseases and tricuspid atresia is necessary. In non-cyanotic patients, differentiation from dilated cardiomyopathy and pericardial effusion is required.
Treatment
Patients with mild symptoms may not require surgery and should be monitored with regular follow-ups.
Patients with significant cardiac enlargement and severe symptoms should undergo surgical treatment.