Approach Considerations
Routine laboratory study results in patients with Ebstein anomaly may be in the reference range. In symptomatic neonates, acidosis may lead to metabolic and electrolyte derangements. Arterial blood gas (ABG) levels determine the severity of cyanosis and indicate the amount of right-to-left shunting at the atrial septal defect.
Electrocardiographic (ECG) findings are almost always abnormal. Right-axis deviation and right bundle-branch block are common. P-wave morphology usually indicates right atrial enlargement, and the PR interval is often prolonged. Because both atrial arrhythmias and ventricular arrhythmias are common, obtain the results of a 24-hour Holter monitor in any patient with a history of arrhythmia or palpitation.
Electrophysiologic studies should be performed in patients with a history of ventricular preexcitation, wide-complex arrhythmia, or syncope. Approximately 30% of patients with Ebstein anomaly will have accessory pathways. [25]
See also the Guidelines section for the 2018 American Heart Association/American College of Cardiology (AHA/ACC) recommendations for the management of adults with Ebstein anomaly.
Imaging Studies
Chest radiography
The heart shadow may be normal or marked by massive cardiomegaly. Typically, the shadow of the great vessels is narrow because of a small aorta and main pulmonary artery. Right atrial and right ventricular enlargement produces a heart shadow with a globular shape. The apical region of the left ventricle may be elevated from the diaphragm, as seen in right ventricular enlargement (see the image below).
Characteristic chest radiograph of a neonate with Ebstein anomaly. The heart shadow demonstrates cardiomegaly, with evidence of severe right atrial enlargement.
Pulmonary vascularity findings may range from normal to significantly decreased depending on the severity of the defect and the amount of pulmonary blood flow.
A cardiothoracic ratio greater than 0.65 is a predictor of sudden death; some physicians consider this finding an indication for surgery. [15]
Echocardiography
Echocardiography has evolved as the primary diagnostic tool to aid in diagnosing Ebstein anomaly in patients. A well-documented correlation is noted between echocardiography findings and operation or autopsy findings.
Echocardiography can define the morphology of the tricuspid valve as well as specific abnormalities of the leaflets. In addition, the function, thickness, and size of the right and left ventricles can be assessed. Coexisting cardiac lesions can also be identified.
Color flow Doppler allows for better assessment of tricuspid valve incompetence and degree of shunting at the atrial level.
Two systems that classify disease severity have been developed based on echocardiographic findings. The classification of Carpentier is based on tricuspid valve morphology, whereas the classification of Celermajer is based on cardiac chamber size. [9, 26] More recently, real-time 3-dimensional transthoracic echocardiography has provided a more comprehensive assessment of the anatomic and morphologic features in patients with Ebstein anomaly. [27]
If echocardiography is inadequate or indeterminate, cine computed tomography (CT) scanning and magnetic resonance imaging (MRI) are also useful for diagnostic purposes.
Cardiac catheterization
Prior to recent advances in echocardiography, cardiac catheterization was the definitive diagnostic study for patients with Ebstein anomaly. Early studies demonstrated that cardiac catheterization in patients with Ebstein anomaly was associated with an increased risk of arrhythmia and significant mortality. [4] Currently, cardiac catheterization is reserved for patients with associated cardiac defects, previous shunt placements, or possible pulmonary artery stenosis.
During cardiac catheterization, hemodynamic findings usually demonstrate elevated right atrial pressures with a pulse wave contour showing a dominant v wave and a steep y descent. For patients with severe right atrial enlargement, the right atrial pulse wave may be normal despite the presence of severe tricuspid regurgitation.
Right ventricular pressure may be normal or mildly elevated. Significantly elevated right ventricular pressure may be found in patients with right ventricular outflow tract obstruction or elevated pulmonary artery pressures. The demonstration of right atrial pressure in the proximal right ventricle strongly indicates the presence of Ebstein anomaly.
Angiography
Contrast angiography demonstrates right atrial enlargement and displacement of the septal and posterior tricuspid valve leaflets below the true tricuspid annulus. In most studies, the origin of the displaced septal and posterior leaflets can be seen on the right ventricular wall.
If the tricuspid valve is incompetent, contrast often moves back and forth between the right atrium and the right ventricle. Right-to-left shunting of contrast is seen across any atrial septal defect.
In most patients, blood flow through the right side of the heart and pulmonary arteries is slower than normal.
Magnetic resonance imaging
Cine MRI is available in some centers to assess the function of the tricuspid valve and right ventricle. This imaging technique provides more in-depth detail of the exact anomaly.
-
Anatomic features of Ebstein anomaly. Note the atrialized portion of the right ventricle and displacement of the tricuspid valve. AV = atrioventricular.
-
Characteristic chest radiograph of a neonate with Ebstein anomaly. The heart shadow demonstrates cardiomegaly, with evidence of severe right atrial enlargement.
-
Surgical repair of Ebstein anomaly as described by Danielson. (A) The right atrium is incised and reduced, and the atrial septal defect is closed with a patch. The arrow identifies the large anterior leaflet. (B) Mattress sutures with felt pledgets are used to pull the tricuspid annulus and valve together in a horizontal plane, obliterating the atrialized right ventricle. (C) Sutures are tied after all have been inserted. The arrow identifies the septal leaflet. (D) A posterior annuloplasty is used to narrow the orifice of the tricuspid annulus. (E) Completed repair, resulting in a competent tricuspid valve.
-
Surgical repair of Ebstein anomaly as described by Carpentier. The anterior and posterior leaflets are detached from the tricuspid annulus. In type D lesions, fenestrations are used to create interchordal spaces for the passage of blood into the right ventricle outflow tract (insert). Mattress sutures with pledgets are placed in a vertical plane to plicate the atrialized portion of the right ventricle (top right). The anterior leaflet is reattached at the level of the true annulus with a continuous running suture (bottom left). An annuloplasty ring is inserted to reinforce the repair (bottom right).
-
Surgical repair of Ebstein anomaly in the neonate as described by Starnes. The atrial septal defect is enlarged by excising the remaining septum. The tricuspid valve orifice is closed with a Gore-Tex patch, effectively creating tricuspid atresia. A Gore-Tex shunt (not shown) is then placed to connect the innominate artery to the right pulmonary artery. PTFE = polytetrafluoroethylene.
-
Surgical replacement of the tricuspid valve in Ebstein anomaly. (A) The atrialized right ventricle is plicated in a horizontal plane. (B) Sutures are placed on the atrial side of the coronary sinus and atrioventricular node to avoid injury to the conduction system. (C) Sutures are tied with the heart beating and perfused to ensure the conduction system is intact.
-
Surgical replacement of the tricuspid valve using a pericardial patch to avoid injury to the conduction system. The valve insertion is begun anterior to the coronary sinus using a continuous running suture. A glutaraldehyde-treated pericardial patch is sutured to the septal portion of the prosthetic valve sewing annulus. The free margin of the patch is then sutured to the atrial tissue beyond the area of the conduction tissue. AV = atrioventricular.
-
Operative steps for Ebstein anomaly repair. (A) Opened right atrium showing displacement of the tricuspid valve. ASD = atrial septal defect, CS = coronary sinus, TTA = true tricuspid annulus. (B) Detached part of the anterior and posterior leaflet as a single piece. (C) Clockwise rotation of the posterior leaflet edge to be sutured to the anterior leaflet septal edge and plication of the true tricuspid annulus to bring the valve to a uniform level. (D) Completion of valve attachment to the true tricuspid annulus and closure of the atrial septal defect. Used with permission from Elsevier (Fig 1 from Da Silva JP, Baumgratz JF, da Fonseca L, et al. The cone reconstruction of the tricuspid valve in Ebstein's anomaly. The operation: early and midterm results. J Thorac Cadiovasc Surg. 2007 Jan;133(1):215-23).
-
The cardiac silhouette is usually enlarged in Ebstein anomaly. A chest radiograph will usually show an enormous shadow of the right atrium.
-
Pathology of Ebstein anomaly: Dilated right atrium (RA) with inferior displacement of an abnormal tricuspid valve (TV) septal leaflet, which results in a small right ventricle (RV) that is atrialized. ASD = atrial septal defect, LA = left atrium, LV = left ventricle, PA = pulmonary artery, R-L = right to left.
