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MMCTS
(February 20, 2008). doi:10.1510/mmcts.2006.002428 Copyright © 2008 European Association for Cardio-thoracic Surgery
Procedure Surgical correction of Ebstein anomaly: the Zurich approachDivision of Pediatric Cardiovascular Surgery, University and Children Hospital Zürich, Steinwiesstrasse 75, CH-8032 Zurich, Switzerland * Corresponding author: * E-mail:achim.haeussler{at}kispi.uzh.ch
Ebstein's anomaly is a congenital defect primarily due to a failed-development of the tricuspid valve. The defect affects significantly surrounding structures (conducting tissue, right atrium and ventricle), which often need concomitant correction. We have extended our techniques for the repair of conventional atrio-ventricular valve insufficiency to this specific pathology. The video sequences show the repair of a severe form of Ebstein's anomaly with extensive mobilisation of the displaced leaflets and creation of a subvalvular apparatus with artificial chordae. Because of the absence of arrhythmia, the adjunction of ablation surgery to abnormal atrio-ventricular pathways was not necessary in this case and is not demonstrated in the videos.
Key Words: Ebstein anomaly • Maze procedure • Tricuspid valve • Valve repair • Valve replacement
Wilhelm Ebstein, a graduate from Berlin, described the anomaly of the tricuspid valve which bears his name in 1866, at the age of 30. The defect is estimated to occur in about 1–5 per 200,000 live births, accounting for <1% of all congenital heart disease [1, 2].
Clinical presentation and pathological findings Ebstein anomaly is the result of a failure or incomplete delamination of the inner layers of the inlet zone of the ventricles. The septal (and often posterior) leaflets are hypotrophic and displaced within the right ventricle. The anterior leaflet is less affected although its connections with the right ventricle are also abnormal. The attachments of the leaflets are not concentrated to a major papillary muscle but are spread on trabecula of the infundibulum. Regularly, the attachments are muscularised and the leaflet seems to be in continuity with the endocardium. Because of the severe regurgitation, Ebstein anomaly leads to significant secondary changes of the right ventricle and right atrium. The right ventricle is dilated with a so-called atrialised chamber (the space between a virtual normal atrio-ventricular annulus and the actual plane of insertion of the tricuspid leaflets). The wall of the chamber is thinned and shows abnormal motion ranging from mild hypokinesia to frank dyskinesia, with paradoxical motion of the septum and paradoxical expansion of the atrialised ventricle. The right atrium is enlarged and a patent foramen ovalis is found in the majority of patients. The left ventricle is often normal in morphology and function. In adults, with massive dilatation of the right ventricle and septal desynchronisation, the diastolic and systolic functions of the left ventricle can be impaired (this has an impact if one is considering a cavo-pulmonary anastomosis as part of the repair). Conduction disturbances are frequent. First degree atrioventricular block occurs in 40% of patients, partly due to right atrial enlargement and partly due to structural abnormalities of the atrioventricular conduction system [1, 6]. The propension for developing tachyarrhythmias is high in Ebstein patients, with possible fatal outcome in advanced cases. A Wolff-Parkinson-White syndrome is found in 14–20% of Ebstein patients [7, 8] and ectopic atrial tachycardia, atrial flutter, atrial re-entry tachycardia, incisional atrial tachycardia and atrial fibrillation may also occur [9].
Evolution of techniques The principles of valve repair, which include reduction of the atrialised right ventricle, transfer of the valve tissue on an anatomic annulus and reduction of the annulus, were introduced by Hardy and colleagues in 1964. Danielson maintained these principles but with notable modifications and made the procedure reproducible [7]. Carpentier introduced a classification of the disease (Schematic 1) and proposed the detachment of the anterior leaflet with clockwise transfer on the annulus and a longitudinal plication of the atrialised ventricle [10]. Later, his group proposed the reimplantation of papillary muscles on the septum and a liberal use of a cavo-pulmonary anastomosis. Quaegebeur and colleagues contemporarily developed a similar technique with excellent results and without need for ventricular volume downloading [11]. There has been since a huge amount of modifications proposed, the most significant ones have challenged the need for a ventricular plication and the use of a prosthetic ring on the annulus.
Our group has also applied the principles established by Danielson and Carpentier [7, 10], especially regarding the use of the wide anterior leaflet as the acting leaflet. Transfer of the papillary muscle or any attachment of the leaflet to the septum has been part of our approach but in an evolving way. Because of a resulting stenosis in some patients with the conventional implantation, we have shifted the implantation site more distal on the septum to obtain a wider opening and a larger coaptation area. For that, artificial chordae proved to be a better material than the short native attachment structures. Finally, like others, we have tried to recreate a functional septal leaflet to obtain a bicuspid rather than a unicuspid valve [12].
Description of the case Description of the technique After median sternotomy and opening of the sternum, normothermic cardiopulmonary bypass was established between the vena cava and the ascending aorta. A left ventricular vent was inserted through the right superior pulmonary vein. Antegrade cold blood cardioplegia was instituted and repeated every 30 min. The cava were snared and the right atrium was opened. The septal and posterior leaflets were identified (as remnant tissue in this case) as well as the anterior leaflet and its attachments (Video 2). The remnants of the septal leaflet were carefully mobilised and dissected free from the septum (Video 3). They were brought to the antero-septal commissure.
A virtual septal leaflet was created by inserting its base on the endocardium along the line of an anatomic annulus. Shallow bites of Prolene 6/0 on the endocardium were used to avoid any damage to or interference with the nearby conducting tissue (Video 4).
The free edge of the new septal leaflet was supported by three pairs of Goretex sutures anchored on the septum, approximately 2 cm away from the neo-annulus. The length of the Goretex was determined so that the neo-leaflet could stand without prolapsus above its insertion (Video 5).
The anterior leaflet was then mobilised. It was detached from its annulus leaving only a small insertion at the antero-septal commissure (the only part which has a normal position and configuration with a corresponding, individualised papillary muscle) (Video 6).
A plasty after DeVega was performed with a 4/0 Prolene along the neo-annulus from the antero-septal commissure to the neo postero-septal commissure (Video 7).
The anterior leaflet was spread along the septum and the coaptation surface with the septal leaflet and the septum was determined. Its free edge was secured in this position with three to four pairs of Goretex sutures. The sutures were anchored at the junction of the septum with the anterior wall of the right ventricle (Video 8). This transition is remarkable for its change of colour (being yellowish where the anterior wall starts).
The bites should not be too deep to avoid encroaching to the left anterior descending artery. The anterior leaflet was then inserted on the neo-annulus with a running suture of Prolene 5/0 (Video 9). At the postero-septal commissure, the leaflet was sutured on the septal leaflet like for a cleft closure (Video 10).
The valve was tested for competence (Video 11). Fenestrations in the anterior leaflets were closed with simple sutures. The Prolene suture on the annulus was tightened to secure the annuloplasty (Video 12).
The valve was tested again in its final position; the atrial septum defects were closed (Video 13). The heart was deaired and the cross-clamp was removed.
After weaning from cardio-pulmonary bypass, control of the repair was done with transesophageal echocardiography (Video 14).
The described technique is the result of a progressive evolution and has been applied in our last nine patients (consecutive series) with a severe form of Ebstein anomaly. Median age at repair was 15 years (9–32 years). Follow-up was complete with a median time of 36 months (6 months–5 years). At the beginning of our experience, the attachments of the anterior leaflets were inserted in the mid-septum valve (4 patients) but resulted in a reduced excursion of the leaflet and sub-optimal opening. The transfer of the attachments with Goretex chordae farther down the septum (5 patients) resulted in a better excursion of the leaflet and also in an increased opening area under the leaflet. A prosthetic ring was used in one adult patient. An augmentation patch was used in the anterior leaflet in one patient to fill the gap between the mobilised leaflet and the virtual annulus. Plication of the atrialised ventricle was performed in four patients, most of them in our initial experience. The atrial septum was closed in all patients. A cavo-pulmonary anastomosis was performed in one patient and a cryoablation maze procedure of the right atrium in two patients. The valve was repaired in all patients. In our early experience, we noted a transvalvular gradient in two patients (mean gradient of 3 and 4 mmHg), which regressed somehow after extubation. The transvalvular gradient was under 2 mmHg in all our recent patients. No or trivial regurgitation jet was noted in six patients. Mild insufficiency was present in three patients. The insufficiency remained stable in two patients and progressed in one patient who underwent a redo repair at 15 months. All the patients were in sinus rhythm. They are all free of symptoms and medication.
The approach to Ebstein anomaly has evolved with time [10, 11, 13, 14]. While the cardinal principle of transferring the tricuspid valve tissues on a virtual, anatomic annulus has been adopted by most surgeons, the other principles of repair have not uniformly been accepted. Our own approach has followed these lines and has taken advantages of some repair techniques employed for atrio-ventricular valves. In our practice, the insertion of a prosthetic ring on the neo-annulus has virtually been abandoned (something we would probably consider in a few adults). We mark the neo tricuspid annulus with a running suture of Prolene which is adjusted and tightened at the end of the repair. The coaptation surface of the rotated anterior leaflet is determined and secured with Goretex sutures set far away from the annulus. The anterior leaflet is then inserted on the neo-annulus, directly if the gap is small or with an augmentation patch if the gap is large. We no longer routinely plicate the right ventricle unless an aneurysmal dilatation exists, something rare in the young population. Our reluctance against aggressive ventricular plication comes from two reasons. The potential for beneficial remodelling of the right ventricle exists in the young population, as long as muscle is the most important component of the ventricular wall. Kinking and obstruction of a coronary artery (especially the right coronary artery) can occur with aggressive plication. In older patients, the wall of the chronically dilated right ventricle is almost devoided of muscle cells and acts as an aneurysm sac with paradoxical motion [15, 16, 17]. These patients definitively benefit from a plication of the saccular dilatation. We have extended the adoption of Goretex chordae to reconstruct the subvalvular apparatus of a valve in Ebstein anomalies. This choice was done because Goretex chords showed a good longevity on the tricuspid valve even in growing children [18] and because of the fact that almost all our patients were already full grown teenagers or young adults. Goretex chordae allowed us to insert the tension apparatus far away from the neo-annulus (distal from it) with a resultant wider excursion (and therefore larger opening) of the leaflet and larger coaptation area. Other surgeons reinsert so-called ‘native’ papillary muscles directly on the septum [19, 20, 21]. The insertion location is usually only a few centimetres away from the neo-annulus (relatively proximal to the neo-annulus). The hinging line of a leaflet is set by the level of its commissures. With this proximal insertion, the commissures are pulled down toward the septum and result in a narrow opening area. A distal insertion of the subvalvular attachment brings the hinging line higher up and results in a much wider excursion of the leaflet. It must also be stressed that the subvalvular apparatus of the anterior leaflet is seldom clearly defined and rarely concentrated on true papillary muscles. The attachment of the anterior leaflet on the septum resembles a garland, the border of the leaflet being fused with trabeculas. There are very limited openings between these insertion points and a surgical fenestration of the leaflet and attachments is often necessary to improve opening. Still, the effective opening area may remain narrow, able to induce a valvular stenosis in increased cardiac output situations. The insertion of the Goretex sutures on the distal septum allows not only a wider excursion of the leaflet, but also provides an unrestricted flow between chordae, underneath the leaflet. Finally, the distal insertion leaves space on the septum to create a functional septal leaflet (i.e. a bicuspid valve), which also results in a wider opening area. The antero-septal commissure is the native commissure which is usually normal even in the most dysplastic forms of Ebstein anomalies. This commissure is usually supported by a corresponding papillary muscle. The posterior (or infero-septal) commissure must be created. We have adopted a technique close to that described by da Silva and colleagues, where the end of the rotated anterior leaflet is sutured to the reconstructed septal leaflet [12]. The adjunction of a cavo-pulmonary anastomosis in the repair of Ebstein anomaly is differently used by surgical teams. The rationale behind this so-called ‘one and half ventricular repair’ is to reduce the volume load across the tricuspid valve and through the right ventricle [22]. At one extreme of the spectrum, some groups almost never resort to this manoeuvre [7, 11, 23] while others used it in the majority of their cases [20, 24]. Our technique usually allows a wide opening of the tricuspid annulus without residual gradient and therefore without the need for a volume decompression. A cavo-pulmonary anastomosis, although a common operation in congenital surgery, should be used with caution in adults. The increased cerebral venous pressure and its pulsatility are sometime badly tolerated and an important access for electrophysiological intervention is lost. Fenestration of the atrial septum is another useful way to decompress the right heart in neonates [21], especially when the pulmonary resistance has not reached its normal level. It should be used with caution later on because of the risk of paradoxical emboli, which is substantially increased when a mechanical or a functional obstruction exists along the pulmonary circulation. A controversial point in adult patients with severely dystrophic valvular tissues is whether the valve should be reconstructed or replaced [5]. The new generation of biological valves, under a low pressure system, will certainly achieve excellent long-term results, probably close to those obtained in complex reconstructions. The freedom from reoperation in patients with biological valve replacement compared to those with valve repair is not hugely divergent. The Mayo Clinic group reported a freedom from reoperation in 80% of their prosthetic patients in 10 years [25]. The Carpentier's group, with a repaired population, had a freedom of 88% at the same interval [20]. The fact that more favourable patients were in the repair group, tends to validate prosthetic replacement as an option for severely dysplastic valves. The need to volume unload the right ventricle is also seldom required with a prosthetic approach [5, 25]. We would probably favour this approach to a sub-optimal repair with a cavo-pulmonary anastomosis or a fenestrated atrial septum. Arrhythmia due to intrinsic conduction anomalies and secondary dilatation of the atria (and later to surgical incisions) is a common problem in this population [1, 8, 26]. Pre-operative electrophysiological testing should be performed for patients with a history of tachyarrhythmia or with pre-excitation signs on electrocardiogram. Pre-operative radiofrequency ablation is difficult to perform in Ebstein patients for several reasons, the most significant ones being the ill-defined landmarks, the dilatation of the atrialised right ventricle and the specific characteristics of the abnormal pathways. The Mayo Clinic group advocates routine per-operative mapping with surgical ablation consisting in reduction of right atrioplasty, surgical incisions and cryoablation lines (including the atrial isthmus) [1, 8]. As surgeons are getting more accustomed to electrophysiological mapping and ablation, this logical and sound approach will certainly be adopted as an integral part of the Ebstein repair. It should be noted that many groups have achieved excellent long-term results with a wide array of techniques. The multicenter study of the European Congenital Heart Surgeons Association clearly showed that no strong consensus exists in the approach of this heterogeneous pathology [5]. Yet, the overall results are superb with long survival expectancies and excellent quality of life [5, 19, 23, 27]. This emphasises the fact that each surgeon should continue to use the technique he is familiar with, as long as his results match established ones.
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Summary
Introduction
