Ebstein Anomaly Surgery

Ebstein anomaly is a rare congenital cardiac defect/malformation. The primary pathologic finding is abnormal development of the tricuspid valve marked by a downward displacement of the annular attachments of the septal and posterior leaflets of the tricuspid valve into the inlet portion of the right ventricle (see the image below). This downward displacement of the leaflets reduces the distal chamber of the right ventricle, leaving part of the ventricle above the valve as an extension of the right atrium. The entire wall of the right ventricle, both above and below the tricuspid valve, is often thin, dilated, and dysfunctional. In most patients, annular dilatation and malformation of the leaflets result in moderate-to-severe insufficiency of the tricuspid valve. Most patients have an atrial septal defect or a patent foramen ovale, which allows predominant right-to-left shunting at the atrial level. A high incidence of atrial and ventricular arrhythmia, including an association with Wolff-Parkinson-White Syndrome, occurs in these patients.

 

Ebstein anomaly is characterized by remarkable morphologic variability and a broad spectrum of clinical presentations. Consequently, the diagnosis of Ebstein anomaly may be made in symptomatic newborn infants, young adults, or middle-aged adults, depending on the severity of the defect and clinical manifestations.

This defect accounts for less than 1% of all congenital heart disease.[1] Geographic variation in the prevalence of this defect, inside or outside the United States, has not been documented. Although no increase in prevalence has been documented, an improvement in diagnostic techniques has led to earlier diagnosis. The anomaly occurs in both sexes with equal frequency.

History of the surgical procedure

In 1866, Wilhelm Ebstein, a young physician in Breslau, Poland, reported findings from a postmortem examination performed 2 years earlier.[2]  The patient was a 19-year-old laborer who presented with dyspnea and palpitations and was noted to be profoundly cyanotic. In his report, Ebstein described in great detail the morphology and clinical correlations of the congenital cardiac malformation that bears his name. His report provided a strong basis for the subsequent development of surgical techniques for the treatment of this anomaly 100 years later.[3]

Early surgical attempts to treat Ebstein anomaly using palliative shunts resulted in extremely high mortality rates.[4]  In 1958, Hunter and Lillihei described a technique of surgical repair that involved plication of the atrialized right ventricle, closure of the atrial septal defect, and tricuspid valve annuloplasty.[5]  In 1964, Hardy reported the first successful repair of Ebstein anomaly using this technique.[6]

During the 1960s, most attempts to repair the tricuspid valve were unsuccessful, and prosthetic valve replacement became the preferred approach. In 1962, Christian Barnard described the first successful tricuspid valve replacement in a patient with Ebstein anomaly using a mechanical valve.[7]  In the early 1970s, interest once again focused on tricuspid valve repair with a successful technique described by Danielson and colleagues at the Mayo Clinic.[8]  Several modifications of tricuspid valve repair have been described recently, and early results have been successful.[9, 10, 11, 12]

The characteristic finding of Ebstein anomaly is a downward displacement of the attachments of the septal and posterior leaflets of the tricuspid valve below the true tricuspid annulus. These valve leaflets are often hypoplastic and adherent to the endocardial surface of the right ventricle. The commissure between these 2 leaflets is usually the point of maximal displacement. The anterior leaflet is typically larger than normal and sail-like in appearance. The anterior leaflet may be thin and fenestrated, and it may also adhere to the endocardial surface of the right ventricle. Rarely, a leaflet can divide, resulting in a double-orifice valve.[13]

The individual valve leaflets may be larger or smaller than expected. The chordae tendineae and papillary muscles are often abnormal in their number, development, and location. In rare instances, the anterior leaflet may attach to the apical region of the right ventricle and obstruct blood flow through the right ventricular outflow tract. Additionally, the tricuspid annulus is usually enlarged to 2-4 times the normal size.

Anatomic features of Ebstein anomaly are presented in the image below.

The displacement of the septal and posterior leaflets of the tricuspid valve into the right ventricle leaves a portion of the right ventricular wall between the leaflet attachments and the true annulus in continuity with the right atria. This atrialized right ventricle is usually very thin and dilated with a decrease in the actual number of myocardial fibers. The functional right ventricle below the valve may also be thin and dilated with decreased contractile function.

The anatomy of the conduction system is normal; the atrioventricular node is located at the apex of the triangle of Koch, and the sinoatrial node is located at the junction of the superior vena cava and the right atrium. The location of the bundle of His is normal, but abnormalities of the right bundle branch have been described. Accessory atrioventricular connections are present in as many as 20% of patients and are associated with Wolff-Parkinson-White syndrome.[14, 15]

The right atrium is enlarged and may reach enormous size. An atrial septal defect is usually present and ranges from a patent foramen ovale to a large secundum defect. The coronary arteries are normal in distribution, and the right coronary artery is often displaced by the enlarged right atrium and atrialized right ventricle. Associated cardiac anomalies include pulmonary stenosis or atresia, ventricular septal defect, patent ductus arteriosus, tetralogy of Fallot, and coarctation of the aorta.[4, 16] In patients with Wolff-Parkinson-White syndrome, accessory pathways are typically the atrioventricular type and are localized to the right ventricular free wall or to the posterior interventricular septum (bundles of Kent).

Ebstein anomaly of the left atrioventricular valve occurs in up to 75% of patients with L-transposition of the great arteries or corrected transposition of the great arteries. In these patients, displacement of the septal and posterior leaflets is similar to that in right-sided lesions, but the anterior leaflet is usually smaller.[17] In addition, the wall of the functional right ventricle is rarely thin and dilated, and the wall of the atrialized right ventricle is also less thin and dilated. Left-sided accessory pathways have been described only in those patients with Ebstein anomaly of the left-sided atrioventricular valve.

In most patients, the tricuspid valve is incompetent with some degree of functional impairment of the right ventricle. The atrialized right ventricle paradoxically moves with right atrial and right ventricular contractions. The net effect is reduced forward blood flow through the right ventricle and pulmonary arteries. The impaired filling of the functional right ventricle and the incompetence of the tricuspid valve both result in systemic venous hypertension.

The right atrium and the atrialized right ventricle become dilated, often to extreme proportions. In most patients, right-to-left shunting occurs across a defect in the atrial septum and results in cyanosis. The presence of pulmonary hypertension in neonates increases this atrial shunting and can lead to profound cyanosis in newborn infants. In some neonates, right ventricular outflow tract obstruction and pulmonary stenosis or atresia may result in a completely ductal-dependent pulmonary circulation. Both atrial arrhythmias and ventricular arrhythmias may contribute to impaired right ventricular function.

Although the primary pathology involves the right ventricle, patients with Ebstein anomaly may also demonstrate abnormal left ventricular geometry and function. The severity of left ventricular dysfunction is associated with the degree of displacement of the tricuspid valve, the size and dysfunction of the right ventricle, and the severity of paradoxical motion of the interventricular septum.

The exact embryologic cause of Ebstein anomaly is unknown. The tricuspid valve leaflets form by a process of delamination of the inner layers of the inlet portion of the right ventricle. Evidence suggests that the anterior leaflet forms earlier in development than the septal and posterior leaflets. In Ebstein anomaly, the insertions of the septal and posterior leaflets are displaced to the junction of the inlet and trabecular portions of the right ventricle, indicating abnormal delamination.[17] The insertion of the anterior leaflet is at the level of the true annulus. The right ventricle endocardium is often thickened and fibrotic, suggesting that formation of the valve leaflets was interrupted prior to completion of the delamination process. The tricuspid valve is usually incompetent, but it may also be stenotic or even imperforate. In addition, both the atrialized right ventricular wall and the functional right ventricular wall may be abnormally thin and fibrotic.

The observed morphologic variability indicates the complexity of this defect's origin during embryologic development. Interestingly, exposure of the fetus to lithium carbonate during the first trimester has been linked to the development of Ebstein anomaly.[18] Although no specific genetic inheritance pattern has been documented, a familial association has been reported.[4]

Early surgical experience with Ebstein anomaly was associated with high mortality rates in excess of 20%. Over the years, mortality has improved as the disorder has become well understood. Studies from the Mayo Clinic indicate that risk factors for early mortality include body weight less than 10.7 kg (23.6 lb) and age younger 2.5 years.[19]

Over the past 2 decades, the actuarial survial at 5 and 10 years is 92% and 90%, respectively. Another study involving 113 surgical patients revealed a much lower mortality and a higher 5-year survival in children undergoing a bidirectional Glenn compared to children who did not undergo the shunt.[20]

Patients who have moderate to severe tricuspid regurgitation at discharge are at a high risk for reoperation.[21]

Reports indicate that radiofrequency ablation of Wolff-Parkinson-White syndrome in patients with Ebstein anomaly is associated with a lower success rate compared to patients who do not have the congenital heart disorder.[22]

Complications

Potential complications of Ebstein anomaly include the following:

• Arrhythmias

• Sudden death

• Heart failure

• Bacterial endocarditis

• Paradoxical emboli

• Stroke

Parents and/or patients with Ebstein anomaly should be informed that surgery is often required in the presence of symptoms. However, some infants with severe heart dysfunction may not be candidates for surgical repair but may be better suited for a heart transplant. In addition, for those patients who do undergo repair of the anomaly, multiple surgeries may be required in the future.

For patient education resources, see the Heart Health Center, as well as Tetralogy of Fallot, Palpitations (Causes, During Pregnancy, Symptoms, Treatment, Ventricular Septal Defect, Atrial Fibrillation (AFib), Congestive Heart Failure, Pleurisy (Pain, Symptoms, Causes, Treatment, and High Blood Pressure (Symptoms, Sings, Causes, Diet, Medication).

The presentation of a patient with Ebstein anomaly varies widely, depending on the severity of the anatomic abnormality. It ranges from severely ill neonates to mildly symptomatic adults (although an initial presentation of an older patient is rare, as only 5% will survive beyond the fifth decade).[23]   

In general, infants and young children may present with cyanosis which is chiefly due to the right-to-left shunt at the atrial level. Older children may present with decreased exercise tolerance, excessive fatigue, and dyspnea. Many patients will complain of palpitations as a reult of the supraventricular tachycardia or Wolff-Parkinson-White syndrome. Older patients may present with right-heart failure and generalized edema.

Some patients may be completely asymptomatic with a murmur detected during a physical examination, or they may have abnormal findings on an electrocardiogram (ECG) or a chest radiograph.[24]  Presenting symptoms are directly related to the severity of tricuspid valve incompetence, the presence or absence of an atrial septal defect, the degree of right and left ventricular dysfunction, and the presence of arrhythmia and associated cardiac defects.

Beyond the neonatal period, most patients present with dyspnea, fatigue, and some degree of cyanosis. In most patients, exercise tolerance is markedly compromised, and maximum oxygen uptake during exercise is less than half of predicted. Despite these findings, growth and development are usually normal.

The most common clinical presentations by age are as follows:

• Neonates: cyanosis in neonates

• Infants: heart failure

• Older children: incidental murmurs

• Adolescents and adults: arrhythmia and exercise intolerance

Paroxysmal supraventricular arrhythmia occurs in 25-40% of patients; this condition is most often found in teenagers or young adults.[1, 4] Ventricular arrhythmia is also common, and Wolff-Parkinson-White syndrome has been diagnosed in 10-18% of patients.[1, 4] Sudden death due to ventricular arrhythmia may occur in as many as 5-7% of patients.[1] Patients with atrial or ventricular arrhythmia may present with episodes of syncope, near syncope, or recurrent palpitations. Likewise, patients with mild manifestations present as late as the third or fourth decade of life with complaints of palpitation or mild exercise intolerance. The most common causes of death are congestive heart failure, severe hypoxia, and cardiac arrhythmia.[16]

Upon physical examination, jugular venous distention and a prominent v wave in the jugular pulse may indicate severe tricuspid regurgitation. Heart sounds are usually soft, and the first and second heart sounds are widely split. A systolic murmur of tricuspid regurgitation may be heard along the left sternal border, but this may also be due to right ventricular outflow tract obstruction. The liver may be palpably enlarged, but ascites and peripheral edema are rare. Evidence of significant cyanosis may be seen in the extremities.

In summary, the cardiac examination of a patient with Ebstein anomaly may reveal the following:

• The jugular venous pressure will show large A and V waves.

• The presence of cyanosis will be most common in the extremities.

• Palpation of the chest will reveal left parasternal heave.

• Both S1 and S2 may be split.

• If heart failure is present, auscultation may reveal an S3 and an S4.

• A holosystolic murmur will be present, reflecting tricuspid insufficiency.

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.

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).

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.

Consultations indicated in the treatment of Ebstein anomaly include the following:

• Electrophysiologist to manage Wolff-Parkinson-White syndrome

• Cardiac surgeon to manage the heart defect

Indications for surgery

Indications for surgical intervention in patients with Ebstein anomaly include the following:

• Functional New York Heart Association (NYHA) class III or class IV symptoms

• Significant or progressive cyanosis

• Decline in exercise tolerance

• Significant decrease in growth curve

• Severe cardiomegaly (cardiothoracic ratio >0.65)

• Associated cardiac anomalies, including right ventricular outflow tract obstruction

• Refractory atrial or ventricular arrhythmia

• History of paradoxical embolus

Contraindications to the procedure

Patients with Ebstein anomaly and biventricular failure should not undergo attempted repair of the defect, and they should be considered candidates for orthotopic heart transplantation. Neonates with Ebstein anomaly are controversial because some patients with severe defects may not be considered candidates for surgery (except possibly for heart transplantation).

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.

Treatment for Ebstein anomaly must be individualized since the broad spectrum of presentations does not allow for a standardized approach. Although most patients require surgical intervention at some time, some patients who are mildly affected may never require surgery.

When neonates present with cyanosis and acidosis, they should be sedated, intubated, and paralyzed. Inotropic support and intensive medical management are necessary in neonates with severe ventricular dysfunction and congestive heart failure. Metabolic acidosis is managed with sodium bicarbonate infusion. Prostaglandin E1 (PGE1), alprostadil) therapy is initiated to maintain patency of the ductus arteriosus and to improve pulmonary blood flow. In severe cases, inhaled nitric oxide therapy may lower pulmonary vascular resistance and improve pulmonary blood flow. If cyanosis improves, then PGE1 infusion can be weaned as pulmonary vascular resistance decreases. Following weaning from PGE1 therapy, close observation is required to assess whether the neonate oxygenates adequately after closure of the ductus arteriosus.

In older children and adults, medical treatment is confined to management of arrhythmia and symptom relief of congestive heart failure. Surgical therapy should be considered in any patient with progressive symptoms, exercise intolerance, or frequent arrhythmia.

Diet and activity

Patients with heart failure may benefit from a low sodium diet.

As symptoms subside and healing is completed, activity is as tolerated.

The goals of surgical intervention are as follows:

• To increase pulmonary blood flow

• To minimize tricuspid insufficiency

• To reduce or eliminate right-to-left shunting

• To optimize right ventricular function

• To reduce or eliminate arrhythmia.

Ideally, the tricuspid valve can be repaired, which may allow the patient to avoid valve replacement with a bioprosthetic valve and the need for future valve replacement.

Preoperative management should focus on optimal medical management of congestive heart failure and improvement in oxygenation. Neonates who are critically ill may require pulmonary vasodilator therapy and PGE 1 to maintain ductal patency and adequate pulmonary blood flow. In addition, inotropic support may be used to improve cardiac function. Serum electrolyte balance and volume status should also be optimized prior to surgery. In older patients, medical management of atrial and ventricular arrhythmias or catheter ablation of accessory pathways may be necessary.

Most operations are performed using cardiopulmonary bypass, bicaval cannulation, moderate systemic hypothermia, and cardioplegia for myocardial arrest. In neonates, single venous cannulation and a period of circulatory arrest may also be used to complete the repair.

The Danielson repair consists of plication of the atrialized right ventricle in a horizontal plane, posterior tricuspid annuloplasty, closure of the atrial septal defect, and right atrial reduction.[8] The Danielson repair is depicted in the image below.

Plication of the atrialized right ventricle brings the base of the posterior leaflet into the plane of the anterior leaflet. Posterior annuloplasty brings the anterior leaflet closer to both the posterior leaflet and the septal leaflet and reduces the annular diameter. This repair essentially creates a competent monocuspid valve from the large anterior leaflet, which coapts to the free edge of the relocated posterior leaflet and the septal leaflet. The Danielson repair improves right ventricular function by obliterating the atrialized right ventricle and by achieving a competent tricuspid valve. In addition, electrophysiologic mapping for localization of accessory pathways is performed in patients with arrhythmia.

The Carpentier repair consists of plication of the atrialized right ventricle in a vertical plane, detachment and relocation of the lateral posterior leaflet and a portion of the anterior leaflet in the plane of the true annulus, and ring tricuspid annuloplasty.[9] The Carpentier repair is depicted in the image below.

This repair creates a bileaflet valve with the relocated posterior leaflet and septal leaflet serving as one leaflet to coapt with the anterior leaflet. Relocating the septal leaflet and the medial portion of the posterior leaflet to the true annulus is not possible because the ventricular septum cannot be plicated in the same way as the free wall of the atrialized right ventricle. In theory, this technique preserves the height of the right ventricle and restores right ventricular morphology. Carpentier morphologically classified this defect into types A, B, C, and D and proposed modifications for each type. His surgical approach is based largely on the motion and function of the anterior leaflet, as determined by preoperative echocardiography.[28]

Da Silva et al in 2007 described the cone reconstruction of the tricuspid valve, which uses similar principles as the Carpentier technique but reconstructs the tricuspid valve in a markedly different manner.[29] The cone reconstruction is done by mobilizing the anterior and posterior tricuspid valve leaflets from their anomalous attachments in the right ventricle, and the free edge of this complex is rotated clockwise to be sutured to the septal border of the anterior leaflet, thus creating a cone, the vertex of which remains fixed at the right ventricular apex and the base of which is sutured to the true tricuspid valve annulus level. Additionally, the septal leaflet is incorporated into the cone wall whenever possible. Following the creation of the cone, the atrialized right ventricle is longitudinally plicated to exclude its thin part and the atrial septal defect is closed in a valved fashion.[29, 30]

See the image below.

The Hetzer repair consists of reduction in the size of the tricuspid orifice to achieve adequate coaptation of the most mobile leaflet tissue, closure of the atrial septal defect, and right atrial reduction.[10] This repair differs from the Carpentier and Danielson techniques by not including a plication of the atrialized right ventricle. Interestingly, in patients with a cleft anterior tricuspid leaflet, this technique may create a dual-orifice tricuspid valve by approximating the posterior and anterior annulus in the middle of the valve orifice.

Newer techniques to repair the tricuspid valve in patients with Ebstein anomaly have centered on detachment of both the abnormal septal and posterior leaflets and their respective chordae and papillary muscles. This allows complete relocation of the leaflets to the level of the true annulus, but requires successful reimplantation of the papillary muscles of each leaflet. Early results with this type of technique have recently been reported.[31]

The Starnes repair for neonates with Ebstein anomaly consists of patch closure of the tricuspid valve orifice, atrial septectomy, and insertion of a systemic-to-pulmonary artery shunt.[12, 32] The Starnes repair is depicted in the image below.

This repair creates a functional tricuspid atresia in the neonate as palliation to a subsequent single ventricle repair with a Fontan procedure. Free wall resection of the enlarged right ventricle in combination with single ventricular palliative surgery has also been reported.[33] In some neonates, this procedure may result in distension of the right ventricle due to continued drainage of Thebesian veins into the ventricular cavity. Fenestration of the patch closing the orifice of the ventricle may be necessary to avoid this complication.

Tricuspid valve replacement is required if repair is not feasible or successful.[34, 35] Most institutions currently favor the use of porcine bioprosthetic valves for tricuspid valve replacement because mechanical valve replacement in the tricuspid position is associated with a high frequency of valve malfunction and thrombotic complications.[36] Some replacement techniques oversize the bioprosthesis and attach the sewing annulus to the atrial wall proximal to the coronary sinus as shown in the image below.

This avoids suturing in the area of conduction tissue, but it places the coronary sinus in the right ventricle.[37] This type of supra-annular implantation of a tricuspid valve bioprosthesis has been successfully used in adults with Ebstein anomaly to avoid complications related to arrhythmias.[38]

Laks described a modification of this technique using a skirt of pericardium to bridge the conduction tissue and the triangle of Koch.[39] This technique allows placement of the valve at the true annulus, avoids suturing in the area of conduction tissue, and leaves the coronary sinus draining into the right atrium. This modified approach is depicted in the image below.

A shunt from the superior vena cava to pulmonary artery (Glenn shunt) used to be performed to improve pulmonary blood flow in patients with Ebstein anomaly.[40] Early experiences determined this technique to be of limited usefulness in these patients. More recently, the use of Glenn shunts in patients with this malformation has been revisited with more promising short-term results.[41, 42]

The right atrial Maze procedure is a modification of the Maze procedure and has been used to treat atrial arrhythmia in patients with Ebstein anomaly.[37] This procedure may reduce or eliminate atrial arrhythmia by preventing reentry conduction at the atrial level. Currently, accessory conduction pathways can be treated with catheter-based radiofrequency ablation before or after surgical repair.[10]

Heart transplantation has been used in patients with Ebstein anomaly who have experienced failed attempts at repair, in those with severe biventricular dysfunction, and in symptomatic neonates with pulmonary atresia or other major cardiac defects. In addition, mechanical support has been used in infants with severe Ebstein anomaly as a bridge to heart transplantation. Lack of donors for neonates and infants, long waiting times, and current long-term survival make heart transplantation a controversial treatment option.

Postoperative management of the neonate who is critically ill often requires continued therapy to reduce pulmonary vascular resistance by means of ventilator manipulation and PGE 1 or nitric oxide therapy. Sedation with or without paralysis may be useful in the first 24 hours to help maintain hemodynamic and respiratory stability. Inotropic agents are usually necessary to support the poorly functioning right ventricle. Atrial and ventricular arrhythmias should be treated early and aggressively with intravenous therapy.

Postoperative treatment of older children and adults usually requires inotropic support and treatment of arrhythmia. Central venous pressure and waveform should be monitored for evidence of recurrent tricuspid insufficiency (in those patients undergoing valve repair) and right ventricular failure. Most patients can be weaned from ventilator support without difficulty and extubated early (within 12-24 h postoperatively).

Patients undergoing surgical repair for Ebstein anomaly require careful follow-up and echocardiographic evaluation to assess the tricuspid valve and right ventricular function. Following tricuspid valve repair, some patients with mild-to-moderate residual tricuspid incompetency progress to severe regurgitation and ultimately require valve replacement. An early evaluation of right ventricular function also serves as a baseline for comparison with future studies. Patients with medically managed arrhythmia need frequent evaluation to assess pharmaceutical dosing and efficacy.

In the long term, most patients require periodic adjustments of their medications. In addition, regular chext x-rays are needed to assess for cardiomegaly and heart failure. Further, electrocardiograms should also be obtained to look for arrhythmias.

Patients who have postoperative atrial fibrillation or have a tricuspid valve may require long-term oral anticoagulation.

Postoperative complications of Ebstein anomaly repair are often correlated with the age of the patient, severity of the defect, presence of associated defects, and difficulty of the repair. In neonates, the most common postoperative problems are low cardiac output and ventricular failure. Atrial and ventricular arrhythmias may occur. Neonates undergoing a repair to create a single ventricle physiology have shunt-dependent pulmonary circulation and may have complications related to increased or decreased shunt flow or thrombosis.

In older patients, residual tricuspid insufficiency following valve repair may be severe enough to warrant an early return to the operating room for tricuspid valve replacement. Mild or moderate tricuspid stenosis can sometimes occur, particularly in the early postoperative periods, and may be exacerbated in the setting of anemia or tachycardia.[30] Ventricular dysfunction and right ventricular failure may require significant inotropic support during postoperative recovery. Atrial and ventricular arrhythmias occurring in the early postoperative period may be difficult to manage medically, and they may be associated with ventricular dysfunction. In addition, complete heart block may occur with either valve repair or valve replacement, requiring the use of a temporary pacemaker and possibly the implantation of a permanent pacemaker. Myocardial ischemia may occur because the right coronary artery may be compromised by suture plication of the atrialized right ventricle.

Long-term results of surgical treatment in Ebstein anomaly are continuing to improve. Patients who present at a younger age with associated defects or severe symptoms have a worse prognosis. In addition, moderate-to-severe cyanosis, a cardiothoracic ratio greater than 0.65, and New York Heart Association (NYHA) class III and class IV are also predictors of increased mortality.[15, 16, 43, 44]

Danielson and colleagues at the Mayo Clinic have surgical experience with more than 400 patients with Ebstein anomaly.[45] The data have been analyzed for the first 312 patients undergoing surgical intervention from 1972 to 1996. Patients range in age from 9 months to 71 years, with a mean age of 20.7 years. No neonates were in this group.[46]

Tricuspid valve repair was successful in 43% of patients, and bioprosthesis was used to replace the tricuspid valve in 53% of patients.[47] Approximately 4% of patients underwent a Fontan reconstruction or other procedure. In this series, 20 (6.4% early mortality) hospital deaths and 24 (7.3%) late deaths occurred. Forty-four patients had accessory conduction pathways (Wolff-Parkinson-White syndrome) and underwent successful pathway ablation as part of the repair. Fifteen patients underwent right-sided Maze procedures for control of atrial dysrhythmia, and 4 underwent ablation of the atrioventricular node for reentry tachycardia. Seventeen (12.6%) of the 135 patients who underwent valve repair required reoperation for valve regurgitation 1.5-18 years later (mean, 8.7 y). Eight bioprosthetic valves required replacement 1-16 years after implantation.

Reduction in cardiomegaly occurred in most patients. Atrial arrhythmia decreased, and late postoperative exercise testing showed a significant improvement in performance. Maximal oxygen consumption increased from a mean of 47% predicted value preoperatively to a mean of 72% postoperatively. Follow-up of those patients evaluated more than a year after operation determined that 93% were NYHA functional class I or class II. Carpentier, Hetzer, and others have reported similar results using different techniques of repair in much smaller series of patients.[9, 10, 11, 41, 48, 49] The addition of a right atrial Maze procedure to the repair has been successful in reducing or eliminating atrial arrhythmia.[37]

Dearani and Danielson recently reported on their experience with tricuspid valve repair of Ebstein anomaly in young children from 1974-2003. This is an experience of 52 children, aged 5 months to 12 years, with a mean age of 7 years.[50] Early mortality was 5.8% (3 patients), with no mortality since 1984. Freedom from all reoperations at 5, 10, and 15 years was 91%, 77%, and 61%, respectively. Tricuspid stenosis was not described in any patient despite significant somatic growth of these children following tricuspid valve repair.

In their 2013 study on the efficacy of cone reconstruction, Dearani et al reported that early results showed low early mortality (1%). Early reoperation for recurrent tricuspid regurgitation (during the same hospitalization) occurred in 12 patients (13%), tricuspid valve re-repair was performed in 6 patients (50%), and 6 patients (50%) underwent tricuspid valve replacement. On follow up (19.7 +/- 24.7 mo), 98% of patients experienced no or mild tricuspid regurgitation and there was no incidence of late mortality or reoperation.[30]

In infants and children undergoing tricuspid valve replacement, insertion of the largest possible bioprosthetic valve is beneficial to accommodate growth. The durability of a porcine bioprosthesis for tricuspid valve replacement has been favorable, with freedom from reoperation of 97% at 5 years and 81% at 15 years.[37] Furthermore, warfarin anticoagulation is not necessary in the absence of atrial fibrillation.

In 1991 Starnes and colleagues reported a series of 5 symptomatic neonates who underwent closure of the tricuspid orifice, atrial septectomy, and systemic-to-pulmonary artery shunt.[12] All 5 patients (aged 1-9 d) survived, and 2 of them have successfully undergone a Fontan reconstruction. While successful cone reconstruction of Ebstein anomaly in neonates has also been reported,[23] surgical intervention in symptomatic neonates continues to be associated with high mortality in most centers.

Significant lung hypoplasia subsequent to right atrial enlargement in utero may be an important factor in the survival of neonates with Ebstein anomaly.[51] Shinkawa et al found that the overall survival estimates for all neonates undergoing surgical intervention for Ebstein anomaly were 66.7% at 1 year, 62.2% at 5 and 10 years, and 51.9% at 15 years.[52] One-year survival rates for systemic-pulmonary shunt, right ventricular exclusion, and tricuspid valve repair were 89%, 64% and 25%, respectively.

2017 Data by Luxford et al revealed that after surgery, the overall 15 year survival was 67%, with a superior prognosis for those able to be managed medically, compared to those who required surgical or catheter intervention.[53] This study showed that 96% of the survivors were in NYHA class l or ll.

2018 Data on Ebstein anomaly from the Thoracic Surgeons Congenital Heart Surgery Database revealed an overall mortality of 9.2%, with a composite morbidity-mortality of 20.1%. The data revealed that symptomatic disease in early infancy is associated with a very high risk, and it requires multiple surgical procedures.[54]

Ebstein anomaly presents with a wide spectrum of morphologic variability and clinical manifestations across an extreme age range. Controversy still exists regarding the best management of symptomatic neonates. Neonates who are critically ill have an extremely high mortality with or without surgical intervention. If intervention is taken, whether a single ventricle approach ultimately improves the outcome remains uncertain. A definite role for use of the Glenn shunt in the treatment of these patients is also unclear. The role of cardiac transplantation in these patients remains controversial. With advances in fetal cardiac surgery and catheterization, in utero intervention may play a role in fetuses diagnosed with severe forms of Ebstein anomaly and may improve subsequent survival.

In older children and adults who become symptomatic, indications and the timing of surgical repair remain controversial. Fortunately, current surgical techniques have led to increasingly better surgical outcomes and long-term results in this diverse group of patients.

2018 AHA/ACC guidelines for adults with Ebstein anomaly

The American Heart Association/American College of Cardiology (AHA/ACC) released updates to their 2008 guideline for the management of adults with congenital heart disease (CHD) in August 2018.[55, 56]  Their recommendations for adults with Ebstein anomaly are outlined below.

The AHA/ACC classifies the CHD anatomy of Ebstein anomaly as being of moderate complexity (II).[55] This disease spectrum includes mild, moderate, and severe variations. Electrocardiographic findings in these patients may include a diagnosis of Wolff-Parkinson-White syndrome.[55]

Diagnostic recommendations: Ebstein anomaly

Class IIa (moderate strength, moderate quality from nonrandomized studies)

In adults with Ebstein anomaly, cardiac magnetic resonance imaging (CMRI) can be useful in the evaluation of cardiac anatomy, right ventricular (RV) dimensions, and systolic function. Transesophageal echocardiography (TEE) can be useful for surgical planning if the transthoracic echocardiographic (TTE) images are inadequate for assessing the tricuspid valve morphology and function.

Electrophysiologic study (EPS) with or without catheter ablation may provide benefit in the diagnostic evaluation of adults with Ebstein anomaly and ventricular preexcitation but without supraventricular tachycardia (SVT). EPS (and catheter ablation, if needed) is reasonable before surgery on the tricuspid valve in adults with Ebstein anomaly, even in the absence of preexcitation or SVT.

Treatment recommendations: Ebstein anomaly

Class I (strong recommendation, moderate quality from nonrandomized studies)

Surgical repair or reoperation for adults with Ebstein anomaly and significant tricuspid regurgitation (TR) is recommended when one or more of the following are present:

• Heart failure symptoms
• Objective evidence of worsening exercise capacity
• Progressive RV systolic dysfunction by echocardiography or CMRI

Class I (strong recommendation, limited data)

Catheter ablation is recommended for adults with Ebstein anomaly and high-risk pathway conduction or multiple accessory pathways.

Class IIa (moderate recommendation, moderate quality from nonrandomized studies)

Surgical repair or reoperation for adults with Ebstein anomaly and significant TR may provide benefit in the presence of progressive RV enlargement, systemic desaturation from right-to-left atrial shunt, paradoxical embolism, and/or atrial tachyarrhythmias.

Class IIb (weak recommendation, moderate quality from nonrandomized studies)

Consider bidirectional superior cavopulmonary (Glenn) anastomosis at the time of Ebstein anomaly for adults in the presence of severe RV dilation or severe RV systolic dysfunction, preserved left ventricular (LV) function, and nonelevated left atrial pressure and LV end diastolic pressure.