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MMCTS
(June 26, 2008). doi:10.1510/mmcts.2007.003038 Copyright © 2008 European Association for Cardio-thoracic Surgery
Procedure Ebstein's anomaly: the Broussais approachDepartment of Cardiac Surgery, Hopital Européen Georges Pompidou, 20-40, rue Leblanc, 75015 Paris, France * Corresponding author: Tel.: +33-1-5609 3640; fax: +33-1-5609 2219 sylvain.chauvaud{at}egp.aphp.fr
Ebstein's anomaly is rare, but it is the most frequent cause of congenital tricuspid valve anomaly. For many years valve replacement was performed. Conservative techniques are now preferred due to improvement of the results. The goals of surgery are to restore a normal tricuspid valve function, to preserve the right ventricular contractility and to decrease the risk of rhythm disturbances. Basically, the technique is based on mobilization of the anterior leaflet and longitudinal plication of the right ventricle. A bidirectional cavo pulmonary shunt is used in severe cases. Results are correlated with the severity of the disease, the expertise of the surgical team and also with the perioperative management.
Key Words: Cyanosis • Ebstein's anomaly • Tricuspid valve
The Ebstein's anomaly is a congenital tricuspid valve anomaly associated with various degree of right ventricular (RV) dysfunction. The basic valvular lesion is a downward displacement of the attachment of the septal leaflet, superior to 8 mm/m2 or 15 mm in infants and 20 mm in adults [1]. The atrialized RV is situated between the attachment of septal leaflet and the atrio ventricular junction (annulus) (Schematic 1). The extension of this chamber is correlated with the displacement of the septal leaflet (Photo 1). There is a large spectrum of severity of the anatomic lesions. The Carpentier classification [2] is used in order to quantify the disease (Schematic 2). With various degree four features are present:
The hemodynamic consequence of the Ebstein's anomaly is a tricuspid insufficiency; association with a stenosis is rare. Symptoms early after birth are respiratory and cardiac failures with cyanosis. In neonates, the anomaly is predominantly ventricular and requires specific management. In children and adults, the symptoms and the principles of treatment are similar. However, rhythm disturbances and RV impairment increase with age.
Preoperative evaluation
Indications They are based on symptoms, which usually are associated:
Indications for asymptomatic patients are not usual except when:
The anatomic type correlates with symptoms. Types C and D are highly symptomatic and there is no question regarding the indication for operation. In types A and B, indications for surgery are not based on symptoms. At the present time there are no indications for ‘prophylactic’ surgery except in one instance. In a child with mild symptoms but in whom the right atrium is enlarged with massive tricuspid insufficiency, the risk of early rhythm disturbances is high and could be an indication for surgery.
There are many anatomical types and subsequently many surgical techniques. Valvular replacement was routinely used and always possible. Conservative surgery is preferred for children and adults whenever it is possible. Conservative techniques were initially described by Lillehei and colleagues [5] and Hardy and Roe [6]. A refinement of this technique was elaborated by Danielson and co-workers [7] with transversal plication of the atrialized RV and reduction of the tricuspid annulus. This technique does not treat the restriction of the anterior leaflet and could be used in 40% of the operated patients only. The technique we use since 1980 is well standardized with mobilization of the anterior leaflet and longitudinal plication of atrialized RV [8]. The use of a bidirectional cavo pulmonary shunt (BCPS) in order to decrease the preload of the RV is controversial. However, associated BCPS was demonstrated to be useful in severe cases [9] and is more and more often used [10]. The patient is monitored with a radial artery catheter, central venous pressures in the right jugular vein and in the femoral vein. After opening the sternum, the heart is inspected for evaluation of the RV contractility. The atrialized RV contractility is assessed at the diaphragmatic wall (inferior). A large bulging atrialized RV predicts a severe type. Extra corporeal circulation is established between the vena cavae cannulated selectively and aorta. The superior vena cava is cannulated at the junction with the innominate vein. The operation is conducted with mild hypothermia (body temperature lowered to 30 °C). After cross-clamping of the aorta, the first dose of blood cardioplegia is injected and repeated every 15 min. The right atrium is largely open and a vent is placed in the atrial septal defect. Exposition of the tricuspid valve (TV) is shown in Video 3. The type of the anomaly is correlated with echocardiography. A very severe anomaly with adhesion of the whole anterior leaflet to the RV wall is an indication for valve replacement.
Access of the subvalvular part of the anterior leaflet is obtained by the detachment of the leaflet tissue at the hinge point. The detachment is large from the antero septal to the postero anterior commissure (Video 4).
Mobilization of the anterior leaflet: all the muscular and fibrous bands are divided, from the annulus to the apex (Video 5). The mobilization is stopped when free motion of the anterior leaflet is obtained. When the anterior leaflet has no chord, the lower part of the leaflet is attached on the moderator band and section of this muscular structure gives some more motion. Mobilization of the anterior leaflet can also individualize an antero lateral papillary muscle included in the ventricular wall.
Plication of the atrialized RV: the shape of this chamber is a triangle, the summit is the apex of the RV, the base is the annulus, one side is the junction of the atrialized RV with the ventricular septum and the other side is the adhesion of the anterior or posterior leaflet on the RV wall (Video 6).
By performing the plication the tricuspid annulus diameter is tremendously reduced. In children the reduction of the annulus is calibrated on a Hegar dilator, according to the normal size for the age. A suture on the atrial wall is necessary to close the cavity. Suture of the anterior leaflet is performed with a clockwise rotation and 6/0 Prolene. The suture is stopped at the level of the coronary sinus (Video 7).
Checking of the TV competence is done with injection of saline in the RV (Photo 2) (Video 8).
When a residual insufficiency is present and due to the annulus dilatation, additional stitches are placed on the posterior part on the annulus. A prosthetic ring is implanted in an adult. One other cause of residual leak is the persistent restriction of the anterior leaflet, it is the reason why the mobilization is so important to obtain a good result. The atrial septal defect or patent foramen ovale is closed, except in very severe impairment of the RV contractility. The right atrium is closed with a double running suture. Bidirectional cavo pulmonary shunt: the right pulmonary artery is dissected from the pericardial adhesions and from the aorta. The superior vena cava is totally dissected and the azygos vein is divided. A large anastomosis is performed with a 7/0 Prolene suture. It is easier to perform the bidirectional shunt under bypass. Indications will be indicated later.
Weaning of bypass A transesophageal echocardiography evaluation is useful to assess the tricuspid valve function and the loading of the left and right ventricles.
Bypass is stopped with low central venous pressure (CVP: 7 mmHg) and low systemic pressure (mean 50 mmHg). Filling is progressive. In a favorable situation, the systemic pressure is increasing without increasing of the central venous pressure. On echocardiography, the left ventricle is empty and gains progressively a near normal size. In a severe case, the arterial pressure does not increase, the RV dilates and the CVP increases. If a bidirectional shunt was not performed it is better to restart bypass and to do the shunt. In such cases an inotrope support is necessary for the RV. Epinephrine (Adrenaline) is used at 0.1 Gamma/kg/min, not exceeding 0.5 Gamma/kg/min. A good result on echocardiography discloses the coaptation of the anterior leaflet on the ventricular septum (Video 9).
From 1980 to 2007, 269 patients (pts) were operated on with this technique. Mean age was 25±16 years (1–70 years). Forty-two percent and 16% were in functional class III and IV, 39% were cyanotic and 58% with permanent sinus rhythm. Associated lesions were atrial septal defect (or PFO) in 46% and reoperation (other centers) in 9%. Ninety-eight percent had conservative surgery and 2% (5 pts) had tricuspid valve replacement. The overall hospital mortality was 9% (24 pts). BCPS was introduced in 1994 and was used in 107 patients. Since this date the operative mortality was 7%. The hospital mortality was related to age and the results were improved with the date of operation (Table 1).
Actuarial survival at 20 years was 80±5%. Eighty-four percent were in functional class I or II. Tricuspid valve insufficiency was 0 or 1+ in 80%, however, 7% had a residual TV insufficiency (grade 3+), usually well tolerated when a bidirectional shunt was performed. Re-operations occurred in 9% (20 pts), 2 were transplanted, 12 pts had a second repair and 6 pts a valve replacement. Eighty-four percent were in permanent sinus rhythm, 5% had residual supra-ventricular tachycardia (usually well tolerated) and 6% had a persistent atrial fibrillation. Seven patients (5%) had an AV Block and a pacemaker was implanted [11].
Considering that there are many anatomic aspects of Ebstein's anomaly, the number of techniques is numerous [12, 13], including partial resection of the RV [14] (Table 2).
In the neonate, the RV is not able to sustain a normal cardiac output. In the Sarnes operation, the tricuspid valve is closed and the pulmonary circulation is maintained with a Blalock–Taussig shunt, then a BCPS and later on a total cavo pulmonary shunt [15]. Several steps of the technique herein described are controversial. The plication of the atrialized RV: when the ventricular wall is not contracting normally (poorly kinetic or dyskinetic), there is an indication for exclusion of the chamber. Longitudinal plication restores a normal shape of the RV. The stitches have to be strictly endocardial, not penetrating the myocardium, in order to avoid coronary arteries injury by direct trauma or by kinking. The indication of the BCPS: the goal of the shunt is to decrease the preload of the RV. In minor forms, type A or B, the BCPS is not indicated. When there is any evidence or doubt on the contractility impairment of the RV, BCPS is useful. In our center, we decreased the hospital mortality with this associated procedure [9]. Pulmonary artery resistance is always low in Ebstein's anomaly, and there is no drawback to perform the shunt in borderline situations. Preoperative evaluation can detect hypokinesia of the effective RV. A paradoxical motion of the ventricular septum with compression of the LV is a safe indication for BCPS (Video 10).
When the endocardium of the atrialized RV is fibrotic (Photo 3), the risk of myocardial fibrosis of the RV is high and a BCPS is performed.
Yellowish patches on the anterior wall of a dilated RV reveal a poor RV condition and are an indication for an associated BCPS (Photo 4).
Surgery of rhythm disturbances: some centers use mapping with ablation of the accessory pathways before or during valve procedure [16]. Electrophysiologic studies showed that the re-entry pathways are on the tricuspid annulus [17]. It is usual to find muscularization of the anterior leaflet with a muscular continuity between the atrial and ventricular walls (Photo 5).
In the technique we used, with desinsertion of the anterior leaflet, most of the accessory pathways are interrupted. The supra-ventricular tachycardia episodes are reduced after surgery but not totally cured. The good results of this technique were confirmed by other centers [18, 19].
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