Ebstein Malformation Surgery Treatment & Management

Treatment for Ebstein malformation 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.^[32] 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.

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, and 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 PGE₁ 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.^[7] 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.^[8] 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.^[33]

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.^[9] 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.^[34]

The Starnes repair for neonates with Ebstein malformation consists of patch closure of the tricuspid valve orifice, atrial septectomy, and insertion of a systemic-to-pulmonary artery shunt.^{[11, 35]} 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. 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.^{[36, 37]} 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.^{[38, 39]} 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.^[40] 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.^[41]

Laks described a modification of this technique using a skirt of pericardium to bridge the conduction tissue and the triangle of Koch.^[42] 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 malformation.^[43] Early experiences determined this technique to be of limited usefulness in these patients. More recently, the use of Glenn shunts in patients with Ebstein malformation has been revisited with more promising short-term results.^[44]

The right atrial Maze procedure is a modification of the Maze procedure and has been used to treat atrial arrhythmia in patients with Ebstein malformation.^[40] 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.^[9]

Heart transplantation has been used in patients with Ebstein malformation 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.^{[45, 46]} In addition, mechanical support has been used in infants with severe Ebstein malformation as a bridge to heart transplantation.^[46] 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 PGE₁ 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 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.

Postoperative complications of Ebstein malformation 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. 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 malformation 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 NYHA class III and class IV are also predictors of increased mortality.^{[20, 25, 47, 48, 49]}

Danielson and colleagues at the Mayo Clinic have surgical experience with more than 400 patients with Ebstein malformation.^[50] The data have recently been analyzed for the first 312 patients undergoing surgical intervention from 1972-1996. Patients range in age from 9 months to 71 years, with a mean age of 20.7 years. No neonates were in this group.^[51]

In the Danielson study, tricuspid valve repair was successful in 43% of patients, and bioprosthesis was used to replace the tricuspid valve in 53% of patients. 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.^{[8, 9, 10, 44, 52]} The addition of a right atrial Maze procedure to the repair has been successful in reducing or eliminating atrial arrhythmia.^[40]

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. 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 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.^[40] Furthermore, warfarin anticoagulation is not necessary in the absence of atrial fibrillation.

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.^[11] All 5 patients (aged 1-9 d) survived, and 2 of them have successfully undergone a Fontan reconstruction. Unfortunately, surgical intervention in symptomatic neonates continues to be associated with a high mortality in most centers. Improvements in the surgical outcomes of this high-risk group have recently been reported.^{[53, 54]}

One study evaluated the outcomes of 32 patients who underwent surgery for Ebstein anomaly. After 16-year follow-up, the results found early and late survival rates of 60% ± 12% versus 85% ± 10 (P = .06), respectively, for patients without pulmonary atresia and early and late survival rates of 60% ± 12% (9/15) versus 94.1% (16/17) (P < .05), respectively, for those with pulmonary atresia. The results conclude that biventricular and tricuspid valve repair of Ebstein anomaly is feasible in neonates and young infants with good results, especially those without pulmonary atresia.^[55]

Ebstein malformation 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 malformation 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.