Ebstein's anomaly is a rare congenital heart defect affecting the right heart, characterized by apical displacement of one or more leaflets of the tricuspid valve, which are abnormally attached along the wall of the right ventricle. This condition leads to a partial “atrialization” of the right ventricle, dysfunction of the tricuspid valve with varying degrees of regurgitation, and a variable impairment of right heart contractile efficiency.
The estimated prevalence is about 1 in 200,000 live births, with marked phenotypic variability. In some patients, the defect is mild and remains undiagnosed until adulthood, while in others it may present during the neonatal period with severe heart failure and cyanosis. The anomaly is frequently associated with other congenital defects, such as atrial septal defects (about 50% of cases), atrioventricular accessory pathways (particularly in Wolff-Parkinson-White syndrome), and more rarely with complex congenital heart disease.
Clinical presentation depends on multiple factors: the degree of valvular displacement, the size of the “atrialized” portion of the ventricle, the severity of tricuspid regurgitation, the functional capacity of the remaining right ventricle, and the presence of atrial shunts. Disease progression can range from a long asymptomatic phase to acute arrhythmic events or congestive heart failure.
Ebstein’s anomaly results from a defect in the embryonic delamination of the tricuspid valve leaflets, occurring between the fourth and seventh weeks of gestation. Normally, the leaflets detach from the ventricular wall and position themselves at the tricuspid annulus. In the pathological form, the septal leaflet and often the posterior leaflet remain anchored lower in the right ventricular cavity.
This displacement leads to a functional malposition of the tricuspid valve, which appears “displaced” toward the ventricular apex. The proximal portion of the ventricle, located between the abnormally inserted valve and the anatomical annulus, loses its contractile function and becomes part of the right atrium, producing the classic picture of “atrialization of the right ventricle”.
Most cases are sporadic, but familial forms with autosomal dominant inheritance have been described, associated with mutations in the NKX2.5 gene, which is involved in the development of endocardial structures. Other molecular alterations, such as those involving MYH7, have been linked to complex phenotypes including valvular anomalies and cardiomyopathies.
In addition to direct causes, several risk factors have been identified that increase the likelihood of developing the anomaly:
From a pathogenetic standpoint, incomplete delamination of the valve leaflets results in an abnormal, incompetent tricuspid valve that allows systolic regurgitation. The remaining right ventricle, reduced in volume and subjected to pressure and volume overload, tends to dilate and develop early dysfunction.
The main pathophysiological alterations include:
Atrial dilation predisposes to the onset of atrial arrhythmias, including flutter and fibrillation, while the presence of accessory pathways may trigger atrioventricular reentrant tachycardias. In neonates with critical forms, impaired right heart function combined with intracardiac shunting can result in severe hypoxemia and hemodynamic collapse.
The clinical presentation of Ebstein’s anomaly is extremely heterogeneous and depends on multiple factors: degree of leaflet displacement, function of the remaining right ventricle, severity of tricuspid regurgitation, and presence of atrial shunts. The age of onset may vary from birth to adulthood, ranging from severe neonatal forms to late-onset asymptomatic or mildly symptomatic cases.
In neonates with critical forms, symptoms may appear within the first hours or days of life, with signs of reduced systemic perfusion and hypoxemia. The condition is often worsened by a large right-to-left shunt at the foramen ovale, allowing deoxygenated venous blood to enter the systemic circulation. Main clinical signs include:
In older children and adolescents, milder forms may present with subtle, progressive symptoms related to physical activity. The most common findings are:
In these patients, a right-to-left atrial shunt may cause mild or intermittent cyanosis, which worsens with physical effort. In chronic forms, this may be associated with digital clubbing. Atrial arrhythmogenicity increases over time due to progressive right atrial dilation, predisposing to flutter, atrial fibrillation, or reentrant tachycardias in the presence of accessory pathways.
On physical examination, the most common finding is a holosystolic murmur due to tricuspid regurgitation, best heard along the lower left sternal border and accentuated during inspiration (Carvallo's sign). With significant right atrial dilation, a sustained right parasternal impulse or epigastric systolic lift may be palpated. The second heart sound may be split or diminished in intensity.
Finally, in a minority of cases, Ebstein's anomaly is diagnosed incidentally during evaluation for a murmur or during arrhythmia screening, particularly in patients with documented ventricular pre-excitation on ECG. In such cases, the condition may be clinically silent despite significant morphological abnormalities.
The diagnosis of Ebstein’s anomaly is based on the integration of clinical presentation, physical examination, and cardiac imaging, with echocardiography as the first-line investigation. The suspicion arises in the presence of unexplained cyanosis, abnormal heart murmurs, signs of heart failure, or arrhythmias, both in the neonatal period and in young adults.
On auscultation, a typical finding is a holosystolic murmur due to tricuspid regurgitation, best heard along the lower left sternal border and accentuated during inspiration. A split second heart sound and a mid-systolic click from abnormal valvular opening may coexist. The presence of central cyanosis with a low-pitched systolic murmur should always raise suspicion of a valvular anomaly with an associated atrial shunt.
The electrocardiogram may show various abnormalities, including:
Chest X-ray may reveal right atrial enlargement, with a globular cardiac silhouette and prominence of the right heart border. In some cases, decreased pulmonary vascular markings may be seen, consistent with a right-to-left atrial shunt.
The key diagnostic tool is transthoracic echocardiography, which allows assessment of:
A commonly used echocardiographic diagnostic criterion is the measurement of the distance between the insertion of the septal leaflet of the tricuspid valve and that of the mitral valve on the apical four-chamber view. A value greater than 8 mm/m² of body surface area is suggestive of Ebstein’s anomaly.
In patients with limited acoustic windows or for more accurate volumetric assessment, cardiac magnetic resonance imaging (CMR) is indicated, providing detailed information on right ventricular morphology, regurgitant volume, and the extent of atrialization. In selected cases, computed tomography may also be useful, particularly when complex surgical planning is required.
In patients with documented or suspected arrhythmias, invasive electrophysiologic study is essential to locate and treat accessory pathways by catheter ablation, often required before or in conjunction with surgical correction.
Finally, cardiac catheterization may be indicated when precise hemodynamic evaluation is necessary, particularly to measure cardiac output, assess atrial shunting, or evaluate pulmonary pressures before surgery.
The management of Ebstein’s anomaly depends on several factors: patient’s age, severity of tricuspid regurgitation, function of the right ventricle, presence of atrial shunts, and arrhythmic complications. Treatment can be conservative, medical, interventional, or surgical, and must be tailored to the clinical course.
In asymptomatic patients with preserved biventricular function and mild tricuspid regurgitation, only periodic clinical and instrumental monitoring is indicated, without the need for active treatment.
Medical therapy is reserved for patients with signs of right-sided congestion or arrhythmias and may include diuretics to reduce volume overload and relieve venous congestion; beta-blockers or antiarrhythmic agents to control atrial or pre-excitation-related tachyarrhythmias; and anticoagulants in patients with atrial fibrillation or significant atrial dilation to prevent thromboembolic events.
In the presence of accessory pathways and reentrant tachycardias, catheter ablation is the treatment of choice, with high efficacy and low procedural risk. In case of arrhythmia recurrence, ablation may be repeated or combined with surgical correction.
Surgical treatment is indicated in symptomatic patients with severe tricuspid regurgitation, right ventricular dysfunction, or cyanosis due to significant atrial shunting. The procedure may consist of:
In more complex cases, with a severely hypoplastic or dysfunctional right ventricle, a palliative approach with cavopulmonary shunts (such as Glenn or Fontan procedures) may be required, or in end-stage cases, heart transplantation.
Prognosis depends on the anatomical and functional severity of the defect and the timeliness of intervention. Patients with mild, well-compensated forms and no significant arrhythmias have excellent long-term survival and a normal quality of life. Early intervention in moderate or severe cases can prevent progression to heart failure and improve arrhythmia-free survival.
However, even after surgical correction, residual right ventricular dysfunction, persistent tricuspid regurgitation, or arrhythmic recurrence may occur, necessitating long-term specialized cardiology follow-up.
Complications of Ebstein’s anomaly depend on the severity of the anatomical defect, the presence of atrial shunting, right ventricular function, and the management approach. In untreated mild forms, the risk is limited, but progressive tricuspid regurgitation or atrial dilation may lead to hemodynamic deterioration over time.
One of the most frequent complications is the development of atrial arrhythmias, particularly flutter, atrial fibrillation, and reentrant tachycardias associated with accessory pathways. Incidence increases with age and the degree of right atrial dilation, and may lead to syncope, palpitations, and—rarely—sudden death, especially in cases of untreated ventricular pre-excitation.
Cyanosis, when due to right-to-left atrial shunting, can result over time in polycythemia, digital clubbing, and increased risk of paradoxical embolism. Ischemic stroke or systemic embolism may occur even in patients in sinus rhythm, particularly if the atrial septal defect is persistent.
In patients who have undergone surgical correction, the most common complications include:
In some cases, despite technically successful surgery, progressive deterioration of right heart function may occur, leading to chronic congestive heart failure. In end-stage presentations, heart transplantation may become necessary.
In forms associated with genetic mutations or familial cardiomyopathies, progression to biventricular involvement or malignant ventricular arrhythmias may occur, requiring implantable cardioverter-defibrillator (ICD) placement in high-risk patients.
Long-term specialized follow-up is essential, with clinical, echocardiographic, and arrhythmia monitoring, to detect early structural or electrical complications and adapt the therapeutic strategy over time.