Surgical Management of Ebstein’s Anomaly in the Adult

Ebstein's anomaly is a rare cardiac malformation that affects the tricuspid valve, right ventricle, and right atrioventricular junction. These anatomical and functional abnormalities cause important tricuspid regurgitation that results in right atrial and right ventricular dilatation and atrial and ventricular arrhythmias. Diagnosis is made by echocardiography. Operation includes tricuspid valve repair or replacement, closure of any interatrial communications, and appropriate antiarrhythmia procedures. Repair of Ebstein's anomaly eliminates right-to-left intracardiac shunting, improves exercise tolerance and functional class, and reduces supraventricular arrhythmias. In addition, quality of life and longevity are improved.

Morphological aspects of Ebstein's anomaly in adults

The essence of the Ebstein's malformation is that the tricuspid valve leaflets do not attach normally to the valve annulus, and the effective orifice is displaced downward into the right ventricular cavity at the junction of the inlet and trabecular components of the right ventricle. Only the septal and posterior leaflets are displaced and divide the right ventricle into two portions. The inlet portion is usually integrated functionally with the right atrium ("atrialized portion"), while the other, including the trabecular and outlet portions, constitutes the functional right ventricle. The proximal atrialized right ventricle often has a wall thinner than the distal functional right ventricle, due to partial congenital absence of myocardium. An atrial septal defect is present in more than one-third of hearts, and the majority of the remainder has a patent foramen ovale resulting in a right-to-left shunt. The downward displacement of the septal tricuspid valve leaflet is associated with discontinuity of the central fibrous body and septal atrioventricular ring, thus creating a potential substrate for accessory atrioventricular connections and ventricular pre-excitation making the patient at risk of sudden death. Angiography has demonstrated that a significant number of patients with Ebstein's anomaly also have morphofunctional abnormalities of the left ventricle, which may be explained by increased fibrosis in the left ventricular wall and ventricular septum as demonstrated by histological studies. Regarding embryology, the leaflets and tensile apparatus of the tricuspid valve are believed to be formed mostly by a process of delamination of the inner layers of the inlet zone of the right ventricle. The downward displacement of the leaflets in Ebstein's anomaly suggests that delamination from the inlet portion failed to occur.

[Ebstein's anomaly: valvular replacement in pediatric patients]

The surgical treatment of Ebstein's anomaly is still controversial. Therefore we have retrospectively studied the results of tricuspid valve replacement (TVR) performed for this anomaly at Sainte Justine Hospital. From October 1977 to December 1997, 9 patients with Ebstein's anomaly, aged from 31 to 248 months (mean 176 +/- 66), have undergone TVR. Eight children were in functional class III or IV (NYHA), while one was in class II. Seven patients underwent plication of the atrialized right ventricular segment. Eight bioprostheses (ranging in diameter from 31 to 35 mm) and one mechanical prosthesis (21 mm) were used. The valve was implanted on the tricuspid annulus in six cases. There was no operative death, nor postoperative complete heart block. Follow-up ranged from 11 to 264 months (mean 91 +/- 84). One late death occurred unrelated to surgery. The probability of 20 years survival is 88%. One patient required a second TVR 162 months after the first surgery because of bioprosthesis failure. Seven of the surviving patients are in functional class I, while one patient is in class II. This experience suggests that TVR with bioprosthesis is a good therapeutical option for children with Ebstein's anomaly since the operative risk is low, the functional status improved in all patients and the durability of bioprosthesis in tricuspid position has been good.

[A pathological study of valvular dysplasia and attachment in Ebstein's anomaly]

Forty hearts with Ebstein's disease of the tricuspid valve were studied in order to correlate dysplasia and attachment of tricuspid valve leaflets at the ventricular walls, atrialization of the right ventricle and fibrosis in this chamber. The correlation was positive. The right ventricular atrialization was directly proportional to leaflet attachment; the correlation in severity between leaflet attachment; the correlation in severity between leaflet attachment and dysplasia was positive in 45%. The right ventricular fibrosis was very frequent in the group with patent pulmonary valve (90%), and the contrary was in the group with pulmonary valve atresia (10%). The structural damage in the right ventricular wall was directly proportional to leaflet attachment in hearts with patent pulmonary valve (90%); in all of these hearts the anatomic annulus of the tricuspid valve was enlarged but in hearts with pulmonary valve atresia this feature only occurred in 10%. The specimens with atrioventricular discordant connexion, the anatomic annulus size, the degree of leaflet attachment, the dysplasia of the tricuspid valve as well as the fibrosis of the wall of the right ventricle were less severe compared with those hearts with concordant atrioventricular connexion. Ebstein's disease of the tricuspid valve is characterized by a disorder in the histodifferentiation of the right ventricle and the tricuspid valve which originates in great part from it.

Outcome in neonates with Ebstein's anomaly

The presentation and outcome of 50 patients with neonatal Ebstein's anomaly seen from 1961 to 1990 were reviewed. The majority (88%) presented in the 1st 3 days of life; cyanosis (80%) was the most common presenting feature. Associated defects, present in 27 infants (54%), included pulmonary stenosis in 11 and atresia in 7. Nine patients (18%) died in the neonatal period; there were 15 late deaths (due to hemodynamic deterioration in 9, sudden death in 5 and a noncardiac cause in 1) at a mean age of 4.5 years (range 4 months to 19 years). Actuarial survival at 10 years was 61%. A new echocardiographic grade (1 to 4 in order of increasing severity of the defect) was devised with use of the ratio of the area of the right atrium and atrialized right ventricle to the area of the functional right ventricle and left heart chambers. Cardiac death occurred in 0 of 4 infants with grade 1, 1 (10%) of 10 with grade 2, 4 (44%) of 9 with grade 3 and 5 (100%) of 5 with grade 4. In a multivariate analysis of clinical and investigational features at presentation, echocardiographic grade of severity was the best independent predictor of death. Neonates with Ebstein's anomaly have a high early mortality rate and those surviving the 1st month of life remain at high risk of late hemodynamic deterioration or sudden death. Echocardiographic grading of severity of the defect permits prognostic stratification.

[Current aspects of Ebstein's disease]

Ebstein's disease is a rare affection which is more and more frequently discovered since the advent of sonocardiography. As a matter of fact, except in the loud but less frequent neonatal forms, Ebstein's disease appears, most of the time, in the first three decades of life under various, misleading forms. The diagnosis is, today, greatly facilitated by bi-dimensional sonocardiography. This technic enables in fact to precisely define, in typical forms, the different abnormalities of the entire tricuspid valve complex; however, there are also atypical forms which should not be ignored. The prognosis of Ebstein's disease is dominated by rhythm disorders, which should be systematically looked for, and will benefit from modern treatments, and cardiac insufficiency. In this field, recent surgical techniques have also greatly improved so that surgery should be considered as soon as the symptoms become worse (Class III of NYHA).

The role of echocardiography in assessing the functional class of the patient with Ebstein's anomaly

In 23 patients with Ebstein's anomaly of the tricuspid valve, the functional class of the patients has been related to the echocardiographic parameters generally used to diagnose this disorder. These are the extent of apical displacement of the tricuspid valve and the delay in tricuspid valve closure time related to that of the mitral valve. In addition, the functional class of the patients has also been evaluated in relation to the severity of tricuspid valve insufficiency and to the presence or absence of associated cardiac abnormalities. The study revealed that the echocardiographic parameters i.e. the degree of apical displacement of the tricuspid valve and the delayed closure time of the tricuspid valve have no predictive value for the patient's clinical condition. On the other hand, both tricuspid valve insufficiency and the presence of additional anomalies have a direct correlation with the well-being of the patient.

Clinical classification of Ebstein's anomaly

Twenty-six patients with Ebstein's anomaly were classified into three types according to their clinical features, heart catheterization data, angiocardiographic and anatomical findings which were obtained on surgery or autopsy. The hemodynamics in each type were discussed. 1. Tricuspid Stenosis Dominant Type. Eight patients, who were cyanotic and had severe symptoms, mild to moderate cardiomegaly, and the "double-ball sign" on angiocardiography were classified into this type. A pressure gradient across the tricuspid valve was demonstrated in 5 patients. 2. Tricuspid Insufficiency Dominant Type. Four cyanotic patients, who had mild symptoms despite the severe cardiomegaly were grouped into this type. The "double-ball sign" was found in all. In three patients, incompetent tricuspid valve was observed. Tricuspid insufficiency necessitates the volume overwork of the right atrium and the functioning right ventricle, resulting in severe dilatation. 3. Mild Type. Fourteen patients who showed no or mild cyanosis, no or mild symptoms, and mild to moderate cardiomegaly, were classified into this type. It is considered that the adequate cardiac output in these patients is attributable to the good function of the tricuspid valve.

Surgical treatment of Ebstein's anomaly

Neither the role of surgery in Ebstein's anaomaly nor the surgical procedure of choice for its correction are clearly defined. Whether or not the artrialized right ventricle, which plays a major role in the functional abnormalities, should be obliterated in all cases remains unresolved. Of the 26 patients with Ebstein's anomaly seen at the University Hospital between 1953 and 1975, four were treated surgically at this center. All had closure of the atrial septal defect, reconstruction of a tricuspid annulus in the normal position, and insertion of a tricuspid prosthesis and an epicardial ventricular pacemaker. The two patients who also had the atrialized chamber obliterated improved dramatically. Thus, obliteration of the atrialized right ventricle appears to be associated with a better operative result.