Ebstein’s Anomaly

Abstract

Ebstein’s anomaly of the tricuspid valve is a cardiac malformation characterized by downward displacement of the septal and inferior tricuspid valve (TV) leaflets, redundant anterior leaflets with a sail-like morphology, dilation of the true right atrioventricular annulus, TV regurgitation, and dilation of the right atrium and ventricle. The wide variety of anatomic and pathophysiologic presentations of Ebstein’s anomaly has made it difficult to achieve uniform results with surgical repair, resulting in the development of many different surgical techniques for its repair. In 1993, Da Silva et al. developed a surgical technique involving cone reconstruction of the TV. This operation aims to undo most of the anatomic TV defects that occurred during embryologic development and to create a cone-like structure from all available leaflet tissue. The result mimics normal TV anatomy, which is an improvement compared to previously described procedures that result in a monocusp valve coaptation with the ventricular septum. In this chapter, we review the surgical maneuvers that we have used to obtain the best functional TV in cases with several anatomic variations of Ebstein’s anomaly. The cone procedure for reconstruction for Ebstein’s anomaly can be performed with low mortality and morbidity. This tricuspid valve repair is effective and durable for the majority of patients.

1. Introduction

Ebstein’s anomaly of the tricuspid valve is a rare congenital heart malformation that accounts for about 0.5% of all congenital heart defects and 0.005% of all live births [1, 2]. In a report from the Society of Thoracic Surgery (STS) Congenital Heart Surgery Database from 2010 to 2016, there were 494 patients with Ebstein’s anomaly who received index operations in 95 centers [3]. Given the low incidence of this defect, some centers will have limited experience managing patients with Ebstein’s anomaly, suggesting the potential importance of regionalizing care in patients with more complex physiology. Ebstein’s anomaly was first described by Wilhelm Ebstein with the autopsy findings of abnormal tricuspid valves in 1866 [4]. The patient, Joseph Prescher, was a 19-year-old worker who presented with cyanosis, dyspnea, palpitations, cardiomegaly, and distended jugular veins [4]. Ebstein’s anomaly is more than an issue with inferior displacement and rotation of the tricuspid valve, as this anomaly may also involve abnormalities of the right ventricular myocardium and in some cases the left ventricle [5]. This malformation is thought to be due to the defects in the process of “delamination from the underlying myocardium” [6] during the development of the tricuspid valve. Presentation of this malformation varies widely from neonates in extremes to an incidental finding during physical examination in an otherwise asymptomatic adult secondary to the anatomic severity of the tricuspid valve and the associated heart malformations [7].

2. Morphology of Ebstein’s anomaly of the tricuspid valve

2.1 Ebstein’s anomaly is an anomaly with both myocardial and valvular defects

The chief distinguishing feature of an Ebstein’s malformation is the positioning of the hinge point of the tricuspid valve into the right ventricular cavity with an apical and anterior rotated appearance toward the right ventricular outflow tract rather than at its normal location at the atrioventricular junction or annulus, and this is due to failure of the septal and inferior leaflets to delaminate from the underlying myocardium. In addition, Ebstein’s malformation is often accompanied by valvar dysplasia, anomalies of the tension apparatus, and myocardial anomalies, and in severe cases, the dilated thin-walled, atrialized inlet component is divided from the apical tubercular and outlet components by a muscular shelf. Furthermore, an Ebstein’s anomaly may be associated with an atrial septal defect, pulmonary atresia, or congenitally corrected transposition of the great arteries (ccTGA) and less commonly with pulmonary stenosis, a ventricular septal defect, or an atrioventricular septal defect [1, 8].

A normal morphologic right ventricle (Figure 1a and b) is divided into inlet, apical trabecular, and outlet components and has a tricuspid valve with its orifice pointing toward the ventricular apex. The tricuspid valve consists of three leaflets designated anterior-superior, inferior, and septal, and its hinge point is located at the annulus. In addition, the tension apparatus of the septal leaflet is attached to the coarsely trabeculated septal surface, and the pulmonary valve is supported by a complete muscular sleeve separating it from the tricuspid valve.

Figure 1.

Morphology of the right side of a normal heart. (a) Septal surfaces of the right atrium, inlet, and apical components of the ventricle and tricuspid valve. (b) Right ventricular outlet and pulmonary valve and pulmonary trunk.

With an Ebstein’s anomaly, the extent of the area of failed delamination, and the appearance of atrioventricular valve rotation may vary from mild to severe, and the functional orifice of the tricuspid valve opens toward the ventricular outflow tract. In addition, there is variability in the condition of the tricuspid valve leaflets. The delaminated anterior-superior leaflet may be small or severely deformed with fenestrations, and its tendinous cords can be short and thickened, and in other cases, the leaflet tissue may be redundant and located within the right ventricular outflow tract possibly resulting in an element of obstruction. Moreover, the inferior and septal leaflet tissue can be hypoplastic and dysplastic. However, in some cases, the inferior leaflet may be large and curtain-like with fenestrations, some of which may have a fan-like appearance. Figure 2 shows the un-delaminated areas of the septal and inferior leaflets. The functional orifice of the tricuspid valve shows the appearance of slight rotation away from the apical component and toward the outlet component. Both the septal and inferior leaflets are dysplastic at the level of their hinge points. The anterior-superior leaflet is dysplastic with thickened tendonous cords. The right ventricular inlet component shows slight atrialization.

Figure 2.

Right side of a heart with a moderate Ebstein’s anomaly showing the septal and inferior leaflets of the tricuspid valve failure to delaminate from the ventricular wall and a rotational appearing displacement of their hinge points, slight atrialization of the inlet to the right ventricle and a small atrial septal defect at the site of the oval fossa.

Figure 3a shows the severe form of Ebstein’s anomaly with the hinge point located well within the right ventricular chamber and located on a muscular shelf that separates the inlet and apical trabecular components. Proximal to this muscular shelf, the heart shows marked atrialization and dilatation and the septal surface is smooth with loss of trabeculations. The atrialization in hearts with Ebstein’s anomaly can vary from almost non-existent to severe. In severe cases, the atrialized right ventricle can be greatly dilated and affect the shape and function of the left ventricle (Figure 3b) [8, 9, 10]. This heart illustrated in Figure 3a shows two exits from the right ventricle. One outlet from the inlet component is through a functional orifice that faces the pulmonary outlet, and this orifice is a bifoliate opening that functionally closes along a solitary zone of apposition. This bifoliate orifice is created by a tongue of valvar tissue joining the anterior-superior to the inferior leaflets. A second exit from the right ventricle is through the proximal outlet component and between tendinous cords.

Figure 3.

Heart specimens with severe Ebstein’s anomaly. (a) Right side showing severe dilatation and marked atrialization of the inlet of the right ventricle with failed delamination of the septal leaflet showing a smooth septal surface and the muscular shelf. The inferior leaflet is curtain-like with short chords attaching it to the muscular shelf. The functional orifice is bifoliate and faces the pulmonary outlet. The dash line shows the solitary zone of apposition, and the arrow heads show the second outlet from the right ventricle. (b) Shows the left ventricle with the septum bulging into the left ventricular cavity because of a severe Ebstein’s anomaly of the right side of the heart.

In some cases of Ebstein’s anomaly, the functional bifoliate outlet orifice leaflet can show multiple tendinous cord attachments to the ventricular wall at the junction between the atralized inlet and the apical trabecular and outlet components (Figure 4a), or the bifoliate functional orifice may be the only outlet from the right ventricle (Figure 4b).

Figure 4.

The outlet components of two hearts with severe Ebstein’s anomaly. (a) Shows the bifoliate functional orifice of the tricuspid valve along with multiple tendinous cords attached to the ventricular wall at the junction between the atralized inlet and the functional parts of the right ventricle, the apical trabecular and outlet components. (b) A view of the outlet component from the arterial side showing the functional bifoliate orifice, the only outlet from the inlet and apical components of the right ventricle, directed toward the pulmonary valve. The dash line shows the solitary zone of apposition.

Besides atrial septal defects, Ebstein’s malformations have an association with pulmonary atresia. Figure 5a shows the right side of a heart with Ebstein’s anomaly, which is markedly dilated, shows severe atrialization of the inlet and a very dysplastic atrioventricular valvar leaflet tissue. Figure 5b shows the outlet from this right ventricle illustrating the pulmonary atresia and redundant dysplastic atrioventricular valve leaflet tissue.

Figure 5.

Cardiac specimen with Ebstein’s anomaly and pulmonary atresia and a specimen with congenitally corrected transposition of the great arteries and an Ebsteinoid anomaly. (a) Shows the right side of a markedly dilated heart with Ebstein’s anomaly with failure of delamination of the septal leaflet and pulmonary valvar atresia. (b) Shows the outlet component of this heart showing the dysplastic leaflets of the atrioventricular valve and pulmonary valvar atresia. (c) Shows the septal surface of a left-sided morphologic right ventricle with congenitally corrected transposition of the great arteries (atrioventricular discordant and ventriculo-arterial discordant connections) with an Ebsteinoid anomaly. (Images 5a and 5b used with Robert H. Anderson’s permission).

2.2 Ebsteinoid malformation and congenitally corrected transposition of great arteries

Some patients with congenitally corrected transposition of the great arteries exhibit Ebstein-like malformation of the left-sided morphologic tricuspid valve. Ebstein’s malformation in the setting of the discordant atrioventricular and discordant ventriculo-arterial connections (ccTGA) is less severe than in cases with normal concordant connections. Because Ebstein’s anomaly in the setting of ccTGA is not completely the same as in hearts with concordant connections, it has been suggested that it should be called an Ebsteinoid anomaly. Figure 5c is an example of a heart with ccTGA and an Ebsteinoid malformation in a left-sided morphologic right ventricle.

2.3 Classification

In 1988, Carpentier et al. reported the most described morphological classification [11] (Figure 6) [7].

Figure 6.

Carpentier classification of Ebstein’s anomaly. RA: right atrium, ARV: atrialized right ventricle; FRV: functional right ventricle (modified with permission from reference [7]).

Type A: Mild apical displacement of the tricuspid valve leaflets with the adequate functional right ventricle.

Type B: Moderate apical displacement of the tricuspid leaflets with a moderate reduced size but adequate functional right ventricular volume with freely mobile anterior leaflet.

Type C: Severe apical displacement of the tricuspid valve leaflets with a small functional right ventricle. Anterior leaflet movement is restricted due to abnormal chordal attachments that cause right ventricular outflow tract obstruction.

Type D: Complete non-delamination of the tricuspid valve leaflets with almost complete atrialization of the right ventricle, only infundibular portion of the right ventricle remaining: “Tricuspid sac”.

3. Genetics

The molecular mechanisms underpinning the failed delamination of the tricuspid valve in Ebstein’s anomaly are unknown [12]. Genetic factors resulting in Ebstein’s anomaly may be related to the mutations in myosin heavy chain 7 (MYH7) and NKX2.5. One study reports heterozygous mutations in MYH7 were noted in eight of 141 (6%) patients with Ebstein’s anomaly. Ebstein’s anomaly with left ventricular noncompaction (LVNC) had a higher frequency of MYH7 mutations (6 out of 8) than Ebstein’s anomaly without LVNC [13]. A heterozygous missense mutation in MYH7 was identified in two siblings with familial Ebstein’s anomaly and LVNC [14]. Ebstein’s anomaly is noted to be the cardiac phenotypes for mutations involving NKX2.5 [15]. Genetic anomalies or syndromes were detected in 19 of 243 fetuses (11%) in a multi-center study. Eleven patients were confirmed with Trisomy 21, two patients were noted to have CHARGE syndrome, and two patients were noted to have a 1p36 deletion [16]. There was no association between Ebstein’s anomaly with genetic abnormalities and mortality [16].

4. Environment

Maternal use of lithium during the first trimester was associated with an increased risk of congenital heart defects (2.41%), including Ebstein’s anomaly [17].

5. Pathophysiology

The presentation and pathophysiology of Ebstein’s anomaly depend on the severity of the morphology and associated congenital heart defects. Symptomatic neonates generally present with cyanosis, cardiomegaly, arrhythmias, and congestive heart failure [18]. At the extreme end in Carpentier type C and D of Ebstein’s anomaly, there is severe displacement of the tricuspid valve that results in severe tricuspid regurgitation and an ineffective functional right ventricle. With the physiological elevation in pulmonary vascular resistance typically seen in neonates, the small and ineffective functional right ventricle is unable to generate antegrade pulmonary blood flow, especially when the ductus arteriosus is still patent, which leads to “functional pulmonary atresia.” True anatomic pulmonary valve atresia is also associated with Ebstein’s anomaly and requires a patent ductus (PDA) to provide pulmonary blood flow.

Another serious condition observed in neonatal Ebstein’s patients is a “circular shunt,” where there is ineffective systemic output due to recirculation of blood with a poorly functioning right ventricle and severe tricuspid regurgitation in association with an atrial septal defect and a patent ductus arteriosus. Retrograde flow from the ductus arteriosus (Figure 7 arrow 1) through a regurgitant pulmonary valve (Figure 7 arrow 2) circulates into the right atrium due to severe tricuspid regurgitation (Figure 7 arrow 3) and then passes into the left heart (Figure 7 arrow 5, 6) through an atrial septal defect (Figure 7 arrow 4) for another cycle through this circular shunt via the ductus arteriosus (Figure 7). High perinatal mortality is associated with the presence of a “circular shunt”; in utero NSAIDs constrict the ductus arteriosus improving fetal survival and resulting in greater gestational age at delivery [19]. In neonates, a “circular shunt” creates unstable hemodynamics with severe hypoxia and low-cardiac-output syndrome. Patients may be temporized with mechanical ventilation and inotropic support, but more definitive correction of the physiology with surgical intervention, typically the Starnes procedure may be required [7].

Figure 7.

Diagram illustrating the “circular shunt” physiology.

The goal of medical treatment during the neonatal period is to assist with the generation of antegrade pulmonary blood flow by supporting the functional right ventricle. Antegrade pulmonary flow improves as the pulmonary vascular resistance falls and can be augmented by the initiation of pulmonary vasodilators, such as inhaled nitric oxide (iNO). Prostaglandin infusion is crucial to maintain patent ductus in neonates with anatomic pulmonary atresia. A trial of withdrawing prostaglandin may be required to assess for the presence of functional pulmonary atresia. Early prostaglandin withdrawal may also be necessary for neonates with a “circular shunt.” With less severe forms of Ebstein’s anomaly (Carpentier type A and B), the functional right ventricular can generate antegrade pulmonary blood flow. These neonates may recover out of the neonatal period without any intervention. Such neonates need to be followed into infancy as the tricuspid regurgitation may worsen over time leading to worsening cardiomegaly from worsening right atrial dilatation and thinning out of the atrialized right ventricle [7].

In the neonatal period, cyanosis due to inadequate pulmonary flow and/or right to left shunting, as well as congestive heart failure are the main issues. Neonates with adequate antegrade pulmonary blood flow and a reasonable size functional right ventricle are candidates for a biventricular repair beyond the neonatal period.

Neonates with pulmonary atresia fall into two groups: true anatomic pulmonary valve atresia and “functional pulmonary atresia.” In neonates with Ebstein’s anomaly and anatomic pulmonary atresia, initial prostaglandin administration followed by either stenting of the ductus arteriosus or placement of a surgical Blalock-Tausig shunt may be the option to get out of the neonatal period in patients with an adequate functional right ventricle. When the functional right ventricle is small, patients may undergo a Starne’s repair followed subsequently by a Cone procedure and/or a Fontan procedure.

Neonates with functional pulmonary atresia are often very unstable, as some patients may develop a “circular shunt” with retrograde flow back through the pulmonary valve. Such neonates usually present in extremis and need a Starne’s repair. The strategy for stable patients depends again on the size of the functional right ventricle.

6. Diagnostic studies

6.1 Echocardiogram

Echocardiography remains the mainstay in the diagnosis of patients with Ebstein’s anomaly and guides management decisions regarding surgical strategy. Each patient with the Ebstein anomaly should undergo a comprehensive transthoracic echocardiogram that allows evaluation of the right atrial size, right ventricular size, and function, the accurate anatomy of the tricuspid valve, the right ventricular outflow tract, the pulmonary valve, the atrial and ventricular septum, and left ventricle. This evaluation is crucial for decision-making before surgical repair [20]. Table 1 summarizes the important details elucidated by echocardiogram that need to be evaluated in patients with Ebstein’s anomaly.

Tricuspid valve anatomy and function	Inferior displacement of septal and posterior/inferior leaflets Attachments/tethering of leaflets Rotation of the tricuspid valve orifice toward the right ventricular outflow tract. Coaptation point of TV leaflets TV function – stenosis and insufficiency Muscularization of leaflets
Right ventricle	Size of atrialized RV Functional RV size Abnormal appearing RV myocardium RV function (2D wall motion, tissue Doppler measurements, TR gradient, 3D measures) Abnormalities of right ventricular outflow tract
Pulmonary valve	Pulmonary valve morphology Pulmonary atresia (functional or anatomy) Insufficiency Pulmonary stenosis Supra-valvar pulmonic stenosis
Right atrium	Atrial septal defect Right atrial size
Left ventricle	Compression/abnormal geometry LV diastolic dysfunction Abnormal septal wall motion Left ventricular non-compaction
Associated lesions	Ventricular septal defect Congenitally corrected TGA

Table 1.

Checklist for echocardiography in Ebstein anomaly.

LV, left ventricle; RV, right ventricle; TGA, transposition of the great arteries; TV, tricuspid valve.

The most sensitive and specific echocardiographic finding to diagnose Ebstein’s anomaly is the apical displacement of the septal leaflet of the tricuspid valve. This can be best seen in apical four-chamber views by echocardiography. When indexed to the body surface area, the distance between the hinge point of the septal leaflet of the tricuspid valve and the anterior leaflet of the mitral valve is called the displacement index. A displacement index above 8 mm/m² is considered diagnostic of Ebstein’s anomaly (Figure 8) [21]. However, it is important to note that there are rare cases of “atypical Ebstein” anomaly with normal displacement index [22]. Additionally, there are some cases with a displacement of the anterior leaflet of the tricuspid valve [23]. The evaluation of the tricuspid valve leaflets and attachments can be best performed from an apical view with sweeps posteriorly toward the coronary sinus and anteriorly toward the ventricular outflow tracts. In addition to the displacement, this will clarify septal attachments. It is common to have tethering attachments of the septal and posterior/inferior leaflets of the tricuspid valve to the right ventricular wall. In some cases, the posterior/inferior leaflet is muscularized with muscular attachments to the right ventricular free wall (Figure 9). These attachments are called the linear attachments of the tricuspid valve and they have implications for surgical repair [24]. As the anterior leaflet is usually the larger leaflet and is often sail-like, describing this leaflet’s size and attachments is important to help surgical planning. The parasternal long-axis views allow for an accurate description of the anterior and posterior/inferior leaflets (Figure 10). It is important to note that often, there is a fusion of the anterior and posterior/inferior leaflets creating a bileaflet tricuspid valve, as discussed above. Three-dimensional echocardiography can give important insights into the valve anatomy in many patients and should be used when possible. The tricuspid valve is also often severely rotated toward the right ventricular outflow tract, and this can be seen by parasternal long and short axis views (Figure 11). Additional important features include the annular size, which is often dilated. Also, muscularization and dysplasia of the tricuspid valve leaflets should be evaluated.

Figure 8.

Apical four-chamber view measuring the displacement of the tricuspid valve which is mild in the left panel and severe in the right panel.

Figure 9.

Muscularization and abnormal attachments of the posterior/inferior leaflet of the tricuspid valve by 2D echocardiography and 3D echocardiography showing the muscular “linear” attachments.

Figure 10.

Parasternal long-axis view with a focus on the tricuspid valve showing the anterior and septal leaflet on the left panel and the posterior/inferior and anterior leaflet on the right panel.

Figure 11.

Parasternal short axis view showing the anatomy of the tricuspid valve leaflets and the rotation of the tricuspid valve orifice toward the right ventricular outflow tract. LV: left ventricle, RVOT: right ventricular outflow tract, TV: tricuspid valve.

After evaluating the anatomical features of the tricuspid valve, it is important to evaluate the tricuspid valve function using multiple views. Grading of the tricuspid regurgitation depends on the width of the vena contracta and can be challenging in the malformed valve. Using multiple views helps to clarify the severity of tricuspid regurgitation. The classification can be graded as trivial, mild, moderate, or severe. A width below 3 mm in multiple views is considered mild, while a width of more than 7 mm is considered severe (Figure 12). It is important to note that these criteria are derived from older patients and may not apply to the infant. Furthermore, the evaluation can be challenging when multiple jets exist. In infants, the percentage of the vena contract width to the tricuspid valve annulus is used with a width below 10% considered as mild while above 30% considered as severe [25]. It is also important to note that the orientation of the regurgitant jet can be unusual due to the rotation of the valve and thus using multiple views and sweeps will be essential to clarify the inflow and regurgitation jets. By continuous wave doppler, the tricuspid regurgitation jet velocity is reported as a measure of the ability of the right ventricle to generate pressure. Also, evaluation by Doppler to assess the degree of tricuspid stenosis is important, as some patients may have a significant degree of narrowing of the tricuspid valve orifice. Post tricuspid valve repair or replacement, a mild gradient <6 mmHg is common and should be followed.

Figure 12.

Apical four chamber and parasternal short-axis views showing a patient with Ebstein anomaly and severe tricuspid regurgitation.

An echocardiographic grading system for determining the severity of neonatal Ebstein, The Great Ormond Street score (Celermajer index), is calculated by dividing the combined area of the right atrium and atrialized right ventricle by the combined area of the functioning right ventricle and left heart. At the end of diastole, the measures are taken in the apical four-chamber view. Patients with a ratio of <1 had a 92% survival rate and those with a ratio of >1.5 had a 100% mortality rate [26].

For a variety of reasons, quantifying RV function in the Ebstein anomaly is difficult by two-dimensional echocardiography. Although evaluation of RV volume and function is always challenging by 2D echocardiogram, it is even more difficult to assess in Ebstein’s anomaly. The RV is frequently enlarged (both the atrialized and functional portions) to the point where imaging it totally in one plane is challenging. Although experienced observers may classify right ventricular activity based on qualitative evidence, intraobserver and interobserver variability is very common. To assess ventricular function, the fractional area change (FAC) of the RV can be calculated. This can be determined by tracing the systolic and diastolic areas in the apical four-chamber view or from the systolic and diastolic areas in the apical four-chamber image. This is limited by the inability to visualize the dilated RV in one image in Ebstein patients [25, 27]. Tricuspid Annular Plane Systolic Excursion (TAPSE) has also been used to evaluate the right ventricular function and poses a challenge in Ebstein’s anomaly given the abnormal tricuspid valve annulus and morphology. Tissue Doppler systolic wave S′ of the tricuspid valve has similar challenges [28].

The atrial septum should also be evaluated. Atrial septal defect or patent foramen ovale is very common. Evaluating the size and direction of shunting should be performed. This can be best seen from subcostal coronal and sagittal views. Right to left flow across the atrial septum may result in desaturation at rest or with exercise [29].

The right ventricular outflow tract should also be carefully evaluated. In severe Ebstein cases, the RV outflow tract can become a large part of the functional right ventricle. The function of the pulmonary valve should be evaluated for pulmonary stenosis and regurgitation. This can be achieved from parasternal and subcostal views. There may be true or functional pulmonary valve atresia; the latter is common especially in the immediate neonatal period when there is transient pulmonary hypertension. The presence of a pulmonary insufficiency jet on color Doppler imaging would indicate the functional type of the pulmonary valve atresia.

6.2 Cardiac magnetic resonance imaging

Multimodality imaging can provide crucial preoperative information, such as a functional and structural assessment of the right ventricle and the tricuspid valve anomaly. This data helps with surgical planning and preoperative counseling. Multimodality imaging can provide personalized details of distinct components of the tricuspid valve. While echocardiography provides correct valvar anatomical details and assessment of right ventricular pressure, cardiac magnetic resonance (CMR) enables a more accurate evaluation of the regurgitant fraction and right ventricular function, which complements the information provided by echocardiography.

Before the cone operation, CMR enables functional and anatomical examination of the RV and tricuspid valve abnormality, which is crucial for surgical planning [30]. Preoperative CMR offered extra information in more than three-quarters of patients, according to a study by Johnson et al., with 69% of the findings changing surgical therapy [31] . Leaflet attachments of the posterior/inferior and anterior leaflets to the RV wall can also be assessed using CMR. There are two types of attachments—focal attachments and linear attachments. Normal attachments, such as focal attachments, allow unobstructed communication between the atrialized and functional RV. Linear attachments occur when the leaflet is completely or partially attached to a muscle shelf at the joint (Figure 13).

Figure 13.

Cardiac MRI image showing the muscularization of the tricuspid valve leaflet on a four-chamber view.

Additionally, CMR can measure the degree of displacement and rotation of the tricuspid valve and can also measure the Great Ormond Street Hospital score (Figure 14). Most importantly, CMR gives an accurate assessment of chamber size including atrialized and functional right ventricle and RV function. CMR is the gold standard for RV size and function and overcomes the limitations of 2D echocardiography to measure RV size and function.

Figure 14.

Cardiac MRI image in four-chamber view showing the calculation of the great Ormond street hospital index using the right atrium and atrialized right ventricle area divided by the sum of the functional right ventricle, left atrium, and left ventricle.

6.3 Computed tomography (CT)

CT provides excellent spatial resolution and fast image acquisition. This makes it ideal to image the coronary arteries and vascular anatomy. CT scans are used frequently in procedural planning for a ductus arteriosus stent [32]. The downside of CT scans is exposured to radiation. With improved CT technology using lower radiation and better temporal resolution.

7. Surgical treatment

7.1 Historical evolution

In the beginning, the surgical procedures for Ebstein’s anomaly treatment included systemic-pulmonary anastomosis (Blalock-Taussig and Potts-Smith) closure of atrial septal defect, and anastomosis of the superior vena cava to the right pulmonary artery (Glenn operation, bidirectional cavopulmonary shunt (BCPS)) [33, 34, 35, 36].

In 1960, Weinberg et al. reported the first successful Glenn operation for Ebstein’s anomaly [36]. However, despite the reported improvement of cyanosis and reductions in the patients’ symptoms, Weinberg et al. were cautious in their conclusions, leaving open questions regarding the procedure’s effectiveness.

In 1962, Barnard and Schrire reported valve replacement in a patient with Ebstein’s anomaly who was the first survivor of tricuspid valve regurgitation correction [37]. In this procedure, part of the valve prosthesis ring was sutured in the right atrium proximally to the coronary sinus—a maneuver intended to avoid atrioventricular block.

In 1964, Hardy et al. [38] reported the first successful performance of tricuspid valve repair with transverse plication of the RV atrialized portion. The technique utilized by Hardy et al. had been previously described by Hunter and Lillehei in 1956 [39]. Bahnson et al., at the University of Pittsburgh, published the successful application of the same repair technique and described important anatomical findings in Ebstein’s anomaly specimens in 1965 [40].

The tricuspid valve replacement presented less-than-ideal results with 54% mortality reported by the international cooperative study published in 1974 [41]. Similarly, poor results were also reported by Lillehei et al. [42] and in the published experience of the Mayo Clinic [43].

Danielson et al. developed a modification of Hardy’s technique, to which was added the posterior tricuspid annuloplasty and the right atrium reduction plasty [44]. Similar to Hunter and Lilelehei’s technique, this procedure comprises transverse plication of the atrialized portion of the RV, leading to an approximation of the displaced leaflets and the true tricuspid annulus, obliterating the atrialized right ventricle. Next, the posterior part of the tricuspid annulus is plicated to further reduce the tricuspid annulus circumference. This technique became one of the most used surgical repair techniques for the treatment of Ebstein’s anomaly. The Mayo Clinic group accumulated a great deal of experience with Danielson’s procedure, however, 36–65% of cases still required tricuspid valve replacement [45, 46, 47].

In 2006, the Mayo Clinic reported their 30-year experience with the treatment of 186 children under 12 years old with Ebstein’s anomaly [48]. Valve repair using Danielson’s technique had a mortality rate of only 5.8% but this repair was possible in only 52 patients (28%), highlighting the limitations of this procedure. In 117 patients (62%), the TV was replaced by prosthesis, while other approaches were used in the remaining 17 children [48].

In 1988, Carpentier et al. [11] described a new technique for valve repair. In contrast to the transverse plication of the atrialized right ventricular chamber described by Danielson et al. (19), Carpentier’s procedure involved vertical plication of the atrialized right ventricle. Furthermore, they brought the tricuspid valve leaflets to the anatomically correct level, thus achieving good right ventricular morphology. The tricuspid valve annulus was remodeled and reinforced with a prosthetic ring.

Carpentier’s group applied this procedure to the vast majority of anatomical presentations of the disease, but their initial series showed a high hospital mortality rate of 14%, as well as frequent long-term complications [11]. The experience of the Carpentier group, representing the second-largest published series, included an overall mortality rate of 9% [49].

Quaegebeur et al. [50] performed a slight modification in this operation without the use of prosthetic ring. They reported that there was no hospital death, but still observed a high incidence of moderate and severe tricuspid regurgitation.

Many additional surgical techniques were developed, but the wide variety of anatomical and pathophysiological presentations of Ebstein’s anomaly makes it difficult to achieve uniform results with surgical repair. Among them, we highlighted the Hetzer and the Sebening procedures [51, 52]. Some of these techniques were used to treat many patients and are still used in a few centers and in specific anatomical situations.

Sarris et al. [53] reported the collective results of 179 operations from 13 institutions associated with the European Congenital Heart Surgeons Association, which showed a 13.3% in-hospital mortality rate. However, it should be noted that this rate included operations in newborns, which constitute a higher-risk group. Despite using a variety of available TV repair techniques, they accomplished tricuspid valve repair in only 27.3% of patients, with a hospital mortality rate of 7.1% for this procedure.

7.2 The Da Silva Cone procedure

Starting in 1989, we developed and routinely used a new surgical technique that was initially called conical reconstruction of the TV [54]. The surgical goals of this method included undoing most of the tricuspid valve anatomical defects that occurred during embryological development and creating a cone-like structure from all available leaflet tissue. This procedure is illustrated in Figure 15 and aimed to cover 360° of the right AV junction with leaflet tissue, allowing leaflet-to-leaflet coaptation [55]. The result is intended to mimic the normal TV anatomy, with leaflet-to-leaflet coaptation, in contrast to previously applied procedures in which a monocusp valve coapts with the ventricular septum muscle [11, 44, 50, 51].

Figure 15.

Ebstein’s anomaly heart illustration (a) shows the displacement of the septal and posterior leaflets of the tricuspid valve, dividing the right ventricle into two chambers—atrialized right ventricle (proximal to the tricuspid valve) and the functional right ventricle (distal to the tricuspid valve). The cone procedure illustration (b) depicts the tricuspid valve leaflet mobilized and reconstructed in a cone-like shape and reattached to the normal atrioventricular junction, and the atrial septal defect closed in a valved fashion with a single stitch. ASD = atrial septal defect, RA = right atrium, ARV = atrialized right ventricle, functional right ventricle (Modified with permission from reference [55]).

The first 40 patients who underwent this new procedure had a 2.5% mortality rate and none required tricuspid valve replacement. Early postoperative echocardiograms showed a significant reduction of TV regurgitation, while the medium-term follow-up examinations showed substantial clinical improvement and a low incidence of reoperation [56]. We next performed a study with a larger number of patients and longer follow-up [57], with a focus on investigating the need for valve replacement and the recurrence of TV valve failure, which are the problems observed with the techniques of Danielson and Carpentier, respectively [11, 44, 45]. There were four deaths in 52 enrolled patients (7.69%) during the 57 months of mean follow-up with improved tricuspid regurgitation. In addition, the functional area of the right ventricle increased from 8.53 cm²/m² to 21.01 cm²/m² after surgery [57].

Below, we review the surgical maneuvers that we have used to obtain the best functional tricuspid valve repair in several anatomical variations of Ebstein’s anomaly.

7.3 Surgical technique

The operation is performed via median sternotomy, with the institution of a cardiopulmonary bypass through aortic and bicaval cannulation. For myocardial protection, moderate systemic hypothermia (25–28°C) and cold antegrade blood cardioplegia are used, and a subsequent cardioplegia dose is applied at a suitable interval during the cross-clamp period. The main pulmonary artery can be closed by snare placement to maintain a dry RV during valve repair. This also facilitates examination of the TV after repair, when the RV is filled with a saline solution via a bulb syringe or catheter placed inside the RV [58].

The main steps of the cone operation are described below:

Step 1: Exposure and assessment of the tricuspid valve.

This is accomplished by transverse right atriotomy with the placement of stay sutures just above the true valve annulus at the 10, 12, and 3 o’clock positions. The sutures at the 10 and 12 o’clock positions go through the pericardium to avoid annular plane distortion. The left heart is vented by the insertion of a catheter across the patent foramen ovale (PFO) or atrial septal defect (ASD).

Step 2: Mobilization of the tricuspid valve.

The surgical methods used to achieve TV mobilization in cases of Ebstein’s anomaly are chosen according to the degree of anterior leaflet tethering, septal leaflet size, degree of delamination failure of the inferior and septal leaflets, and the axis of the tricuspid opening in relation to the right ventricle outflow tract (RVOT) and to the RV apex. TV mobilization is accomplished by complete sectioning of the abnormal tethering tissues between the tricuspid leaflets and ventricular wall, leaving the leaflet tissues attached to the ventricle only at its distal margin (by normal papillary muscle, cords, or directly to muscle). In most cases, the majority of leaflet tissue is detached circumferentially, except at the 10–12 o’clock positions. This portion usually is attached to the true annulus without tethering to the ventricular wall, thus allowing free movement. In special situations, the leaflets are detached in the full circumference, allowing complete mobilization of the valve. Aggressive detachment of the leaflet down to its distal point is a critical component of this procedure, to free an adequate amount of tissue for cone construction. This also allows sufficient mobility of the leaflet body in the constructed cone, enabling adequate movement during systole and closure with a good coaptation surface.

The anterior and inferior leaflets of the tricuspid valve are mobilized as a single piece (Figure 16), starting with an incision at its proximal attachment to the atrioventricular junction (12 o’clock position) and moving clockwise, toward the displaced inferior leaflet. The incision terminates when the inferior leaflet is completely released from its abnormal proximal attachment to the RV wall. This step provides access to the space between these leaflets and the RV wall, allowing the sectioning of all abnormal papillary muscle, myocardial bridges, and chordal tissues that tether these leaflets to the RV wall. The anterior papillary muscle, which is usually positioned at the anteroposterior commissure, must be freed from its more proximal attachment to the RV wall, retaining only the supports near the RV apex. In some cases, the posterior leaflet must be completely released from its abnormal attachments to the RV to allow its medial rotation to join the septal leaflet, composing the septal aspect of the cone.

Figure 16.

Anterior and posterior leaflets of the tricuspid valve mobilized as a single piece. (a) Anterior and posterior leaflets anatomy—dotted line shows the displaced and the dashed line shows the true tricuspid annulus, (b) anterior leaflet mobilization, (c) section of posterior leaflet proximal connection to RV wall, and (d) the completely mobilized anterior and posterior leaflets (with permission from reference [58]).

The TV anteroseptal commissure is approached with the goal of creating a space between the ventricular septum and the septal aspect of the cone, and of moving the opening axis of the tricuspid valve toward the RV apex. An incision is made at the proximal attachment line of the anterior leaflet, approximately 1 cm anterior to the anteroseptal commissure. This incision is continued counterclockwise down to the septal leaflet, which is mobilized to its lateral limit (Figure 17). Stay sutures are placed at the leaflet’s proximal edge, exposing the subvalvular apparatus of the septal aspect of the anterior leaflet, septal leaflet, and the anteroseptal commissure. The tissues holding the proximal portion of these leaflets to the septum are divided. If the tricuspid valve opens toward the RV outflow tract, it is necessary to mobilize or cut the papillary muscle abnormally attached to the RVOT. The medial papillary muscle is usually related to the anterior and septal leaflet at its commissure, but in some cases, it is fused to the septum and can be deeply freed improving the mobility of that area of the future cone.

Figure 17.

Anteroseptal commissure mobilization. (a) An incision is made at the proximal attachment line of the anterior leaflet continues anticlockwise (b), mobilizes the medial papillary muscle (c), and reaches the septal leaflet (d), which is mobilized as deep as possible (with permission from reference [58]).

Step 3: Cone construction.

The cone is constructed using all available mobilized tissue, via the vertical suturing of leaflets—both inferior to septal and septal to anterior. A 5-0 polypropylene running suture technique is used for adults, while a 6-0 polypropylene interrupted suture technique is applied in children. The cone tends to be narrower posteriorly where there is typically less available leaflet tissue, and thus this area must be widened by vertical incision and horizontal suturing of the leaflet tissue in the constructed cone. The septal leaflet is incorporated into the cone such that the septal part of the cone is longer than the septal vertical distance between the final TV hinge line to its distal attachment to the ventricular septum. Importantly, this allows the septal component of the cone to move anteriorly in the process of coaptation with the anterior component of the cone during systole. Furthermore, this prevents tension at the suture line in the septal aspect of the annular attachment of the cone. If there is not enough leaflet tissue, a piece of the autologous pericardium can be added to this region.

The principal methods of septal leaflet incorporation into the cone are as follows:

1. Placing a vertical suture to join the septal leaflet superior edge to the septal edge of the anterior leaflet, followed by the placement of a second suture line uniting the septal leaflet inferior edge with the lateral edge of the posterior leaflet (Figure 18a–c). This approach is used for septal leaflets that are large after having been mobilized.

2. Combining the septal leaflet with the completely detached posterior leaflet. These leaflet plication and combining maneuvers increase the cone’s depth and reduce its proximal circumference (Figure 18d and e).

Figure 18.

Septal leaflet incorporation: (a) a vertical suture joins the septal leaflet superior edge to the medial edge of the anterior leaflet, (b) and (c) a second suture line unites the septal leaflet inferior edge to the lateral edge of the posterior leaflet. In cases with a small septal leaflet, it is combined with the completely detached posterior leaflet by a vertical suture (d), followed by a horizontal suture (e). V = vertical suture, H = horizontal suture (with permission from reference [58]).

Step 4: Plication of the right ventricle and the true tricuspid annulus.

This step begins with vertical plication of the thin and attenuated RV-free wall. This portion of the atrialized RV is usually aneurysmal and its limits are defined by the triangle formed by the line of attachment of the displaced inferior tricuspid leaflet, the posterior ventricular septal edge, and the posterolateral area of the true tricuspid annulus. RV plication begins with the placement of a 4-0 polypropylene stitch at the distal apex of this triangular-shaped area, and the suture is continued toward the atrioventricular junction, excluding all of the aneurysmal atrialized RV. Initially, for vertical RV plication, we used a 4-0 polypropylene running suture in two layers with gentle superficial bites to avoid coronary injury or distortion. Recently, we modified this technique, placing interrupted 4.0 polypropylene sutures in multiple places to achieve the vertical plication of the RV atrialized portion. This interrupted suture technique is more often used in children. The vertical plication reduces the true tricuspid annulus at the atrioventricular junction. If further reduction is required, sutures are placed first at the anteroseptal and then at the anteroposterior position of the true tricuspid annulus. The true tricuspid annulus must be reduced such that it matches the proximal circumference of the cone. These multiple plications are important to prevent the right coronary artery distortion or kinking that can occur with a large TV annular reduction at a single site. Additional plication with interrupted sutures is applied to the area where the leaflets were tethered to the RV wall, to prevent anterior wall bulging and dilation of the RV. This maneuver mimics the usual trabeculation of the RV.

Step 5: Fenestration of the Cone apex.

The linear attachment of the leaflets can cause obstruction of blood inflow to the RV. To prevent obstruction, fenestrations of the 1/3 distal attachments of the leaflets and division of papillary muscles are usually applied.

Step 6: Cone attachment to the true tricuspid annulus.

The cone is attached proximally to the true annulus over 360 degrees and with no tension in the horizontal or vertical plane (Figures 19 and 20). The proximal cone circumference must be correctly matched to the true annular dimension. If necessary, the true annulus can be further reduced by separate plication at 2–3 o’clock and 9 o’clock, and the cone proximal circumference can be reduced by leaflet plication. The initial attachment and assessment are performed with the placement of 5-0 polypropylene single sutures to achieve an even distribution of the valve in the tricuspid annulus. The suture line is then completed with a running suture. To reduce the risk of heart block, special care should be taken when suturing the area of the annulus just medial to the coronary sinus. In this area, the valve can be sutured in a proximal position, in the Todaro’s tendon. In patients with a fragile adult-size annulus, the use of a prosthetic ring may be considered for reinforcement.

Figure 19.

Cone attachment to the true tricuspid annulus. The constructed cone (a) is reattached to the true tricuspid annulus starting at the anterior position (b) and completing the attachment (c), taking superficial bites when suturing near the atrioventricular node area (arrow) (with permission from reference [58]).

Figure 20.

Cone construction was done by rotation of the posterior leaflet, which was combined with the septal leaflet (a), before attachment to the true tricuspid annulus (b). AL = anterior leaflet, PL = posterior leaflet and SL = septal leaflet (with permission from reference [58]).

Step 7: Atrial septal defect treatment.

The ASD/PFO are closed in a valved fashion, such that blood can be shunted from right to left in the event of postoperative RV failure. The opening size of the resulting orifice should be proportional to the degree of RV dysfunction or enlargement. This can be accomplished with the single-stitch technique in cases of PFO or by using a polytetrafluoroethylene (PTFE) patch with an extension flap positioned inside the left atrium to allow unidirectional blood flow toward the left atrium. In cases of severe RV dysfunction, the single-stitch technique (Figure 20) can be performed with placement near the PFO anterior corner, which will result in a less restrictive PFO. In cases of RV dysfunction, some authors recommend the bidirectional Glenn procedure as an adjunct to Ebstein’s anomaly repair [53, 59, 60, 61, 62]. We have considered using the Glenn procedure in some patients, as we will describe in the neonatal section.

7.4 Special anatomic types of Ebstein’s anomaly

In some anatomical situations, the three leaflets are connected at the commissures and there is a well-formed distal attachment of the TV to the RV. In such cases, the TV leaflets are mobilized from their displaced hinge line and the TV is released from its abnormal connections to the RV wall. Next, some plications are made at the distal and proximal edges of the TV, reducing its proximal and distal circumferences, and widening the septal and posterior leaflets to give it a cone shape.

The cone technique can also be used to treat patients presenting with Ebstein’s anomaly with Carpentier’s type D anatomy. Figure 21 depicts one of our patients who was successfully repaired by taking down the leaflets as a single piece, retaining only the distal direct attachment of the leaflet to the RV. Vertical fenestrations were provided at the distal third of this large leaflet. Then the lateral and medial edges of this leaflet were sutured together, creating a cone-like structure. As in all other cases, the cone was revised and any holes/fenestrations in the proximal 2/3 of the cone’s membranous tissues were closed to achieve a similar circumferential depth and to prevent regurgitation leaks. Furthermore, natural, or surgically created fenestrations should be present at the distal 1/3 of the cone to permit unrestricted forward blood flow in diastole.

Figure 21.

Preoperative magnetic resonance images and intraoperative photos depicts the heart’s anatomy of a 4-year-old girl with type D Ebstein’s anomaly (Carpentier’s classification). Images (a) (b), and (c) show that the tricuspid valve leaflets are tethered to the right ventricle wall and image d shows that there is only a small hole-H communicating the atrialized to the functional right ventricle (with permission from reference [58]).

7.5 Important notes on Da Silva cone technique

The mechanism of tricuspid insufficiency in Ebstein’s anomaly is usually related to restrictive leaflet movements. This occurs due to failure of leaflet delamination that results in more distal hinge line attachment to the RV, as well as to the presence of muscular bridges and abnormal papillary muscles that tether the TV leaflets to the RV wall, restricting their movements. Creating a competent tricuspid valve using the cone technique requires extensive mobilization of the displaced or tethered leaflets. Otherwise, the repair will result in leaflet coaptation failure or excessive tension in the leaflet suture line due to pulling of the leaflet that remained improperly attached to the free RV wall, which will be subject to strong tension when the RV is filled. An understanding of these concepts is essential to minimize the incidence of tricuspid insufficiency after the cone procedure and to prevent postoperative dehiscence of the suture line due to diastolic tension. The septal leaflet is frequently incorporated into the septal aspect of the cone, in combination with the posterior tricuspid leaflet. This is a very important component of the cone technique, as it helps prevent both stenosis and insufficiency of the tricuspid valve.

7.6 Bidirectional Glenn procedure to improve postoperative cardiac output

It is expected that some RV dysfunction will be evident early after the cone procedure due to RV wall damage related to surgical maneuvers superimposed on varying degrees of RV impairment from the Ebstein’s malformation itself. Additionally, myocardial injury may be caused by the extended ischemic time required to perform this somewhat complex operation. With this in mind, we have routinely used a valved ASD that allows blood flow from the right to the left atrium, aiming to reduce RV preload and increase LV preload, thereby helping to prevent low cardiac output due to severe RV dysfunction in the early postoperative period. In most patients, the ASD stays functionally closed from the beginning of the postoperative course. However, approximately 10% of cases evolve with right-to-left blood shunting that can cause a substantial drop in oxygen saturation. In such cases, oxygen saturation usually increases in a few days as RV function improves. Additionally, the resulting RV decompression may prevent excessive tension at the tricuspid valve, decreasing the risk of suture dehiscence and TV regurgitation.

In some studies, the problems related to postoperative RV dysfunction have been addressed by diverting the superior caval blood flow to the right pulmonary artery. Chauvaud et al. [59] used this bidirectional cavopulmonary shunt (BCPS)—also called the Glenn procedure—as an adjunctive procedure to Carpentier’s operation in patients with Ebstein’s anomaly and severe right ventricular dysfunction (36% of procedures). They reported that this combination of procedures led to improved results. Other studies have also reported the use of this technique to reduce RV preload in cases of severe RV dysfunction, thus significantly reducing mortality caused by RV failure [60, 61]. Quinonez et al. [62] also reported the creation of a BCPS as an adjunctive procedure with surgical treatment of Ebstein’s anomaly in 14 patients from the Mayo Clinic (TV replacement in 13 and TV repair in 1). In most cases, this approach was planned in anticipation of RV failure, but it was also sometimes performed as a salvage procedure when faced with postoperative hemodynamic instability. Considering the serious clinical situation of the included patients, the study results were excellent with only one death, outlining the importance of this procedure for a subset of patients. Liu et al. [63] also reported the use of the BCPS procedure in addition to the cone operation in a series of young patients. This group applied BCPS procedure to 67% of patients with Ebstein’s anomaly (20 of 30), which drew our attention. However, their series of young patients had good clinical outcomes at mid-term follow-up. We think this method can be used in children to improve pulmonary circulation in case of residual tricuspid regurgitation after the cone repair. We also believe that it is important to employ one of these two methods after the cone operation to prevent low postoperative cardiac output and to protect the dysfunctional RV from distension. We preferentially use the valved closure of ASD. Despite initial cyanosis in some patients and the possibility of paradoxical thromboembolism, RV dysfunction is completely or partially reversible with time and, consequently, oxygen saturation progressively improves [57]. While the BCPS has the advantage of providing better oxygenation, we do not routinely use it because it may be associated with pulsations of the head and neck veins and other complications [61]. In case of low oxygen saturation (<75%) we add a BCPS for older patients or a small (3.0-mm) modified Blalock-Taussig (BT) shunt. We tend to anticoagulated patients who present a dilated RV and/or right-to-left atrial shunting.

The cone procedure for reconstruction of the TV in Ebstein’s malformation usually provides a full coaptation of the leaflets, resulting in effective and durable tricuspid regurgitation repair in the majority of patients. Therefore, its use has been expanded to patients who previously underwent other types of Ebstein’s anomaly treatment.

7.7 Surgical treatment in neonatal Ebstein’s anomaly

Despite recent medical advances, it remains difficult to manage critically ill neonates with Ebstein’s anomaly. A multicenter study conducted at excellent hospitals reported that surgical or catheter interventions carried high mortality (30%) in newborns with critical Ebstein’s anomaly [16]. Additionally, multivariable analysis showed that the lack of antegrade pulmonary valve flow or the presence of pulmonary regurgitation at the time of diagnosis were powerful hemodynamic risk indicators [16]. That study emphasized the necessity for careful surgical management of this group of patients.

Newborns with Ebstein’s anomaly presenting a dependency on prostaglandins or mechanical ventilation, worsening cyanosis or heart failure, anatomic pulmonary atresia, a circular shunt, will require surgical intervention during the neonatal period [7].

The primary cone repair of neonatal Ebstein’s anomaly is a complex procedure due to the delicate valve tissues and the associated lung immaturity. It can be applied only to a small subgroup of older (over 2-week-old), and stable patients with a favorable TV morphology, such as a large and mobile anterior leaflet, a reasonably sized functional RV with good systolic function, and good pulmonary artery and valve anatomy [64]. In that situation, the procedure by an experienced surgeon would be indicated to correct a severe regurgitation that would limit the pulmonary flow and cause cyanosis. In a few situations, where the tricuspid valve presents more complex anatomy in patients with inadequate forward pulmonary flow, with cyanosis, but without expressive cardiomegaly, or septal impingement to the left ventricle, a PDA stent or a BT shunt can be the initial surgical approach. This stenting procedure has the goal to allow the child to develop the pulmonary circulation and the RV for the next step, which is the Cone procedure applied at 4 or 5 months, resulting in a biventricular repair.

However, the great majority of newborns with Ebstein’s anomaly presenting with heart failure should be addressed with the Starnes procedure that, by decompressing the left ventricle and giving more space to the lungs, offers a better outcome for these very sick babies [65].

The surgical palliation with the Starnes procedure consists of excluding the malformed right ventricle with a fenestrated patch sewn at the anatomic level of the tricuspid valve annulus and creation of a systemic to pulmonary artery shunt to provide the pulmonary blood flow. This procedure allows the decompression of the malformed right ventricle, but also ameliorates the septal impingement to the left, with a significant effect on the systemic left ventricle, which reassumes the globular shape after the Starnes. Any pulmonary insufficiency should be contained, and the coronary sinus must stay on the atrial side of the patch to assure effective decompression of the right ventricle. The atrial communication is enlarged and a reduction atrioplasty opens space inside the chest for the lung development [66]. The modified Starnes procedure is adequate for neonates who are hemodynamically unstable, or even on ECMO support. It is usually successful and helps the patients to survive and to prepare them for other more definitive future procedures.

7.8 The Da Silva Cone repair after the Starnes procedure

Although usually successful, the Starnes approach excludes the right ventricle from the pulmonary circulation. So, after the Starnes operation, these patients were traditionally committed to the single ventricle repair pathway [67], which leads to the undesirable long-term complications associated with Fontan palliation [68]. However, we have demonstrated that it is possible to rehabilitate the right ventricle after the Starnes procedure in patients with Ebstein’s anomaly and pulmonary atresia, achieving 1.5 or two-ventricle repair [69]. We also have shown that in patients with fetal circular shunt physiology who underwent the Starnes procedure as a newborn, it is possible to rehabilitate the RV and the pulmonary valve, resulting in two-ventricle physiology [70], as demonstrated in Figure 22.

Figure 22.

Intraoperative images of the Da Silva cone repair after the Starnes procedure. (a) Exposure of the tricuspid valve, which is covered with the Starnes patch (SP). (b) Removal of the fenestrated PTFE patch, taking care not to damage the anterior leaflet of the tricuspid valve, which is adjacent to the patch. (c) Extensive tricuspid valve mobilization; this is initiated at the anterior leaflet (AL) hinge line and continues clockwise toward the inferior leaflet; here, the inferior papillary muscle is being cut. (d) A second incision is made near the anteroseptal commissure (arrow); the cut continues counterclockwise to mobilize the medial part of the anterior leaflet and the entire septal leaflet from their proximal attachments. The proximal detachment of the septal leaflet (SL) follows the dotted line. (e) The inferior leaflet is rotated medially, and a vertical interrupted suture unites it with the lateral aspect of the septal leaflet. The resulting cone-shaped structure is sutured to the anatomical tricuspid valve annulus, which completes the cone repair. SP = starnes patch, AL = anterior leaflet, SL = septal leaflet (with permission from reference [58]).

Bearing in mind that the cone repair can follow the Starnes procedure, we prefer to use a Gore-Tex patch to exclude the RV in the Starnes procedure, because it causes less adhesions, facilitating its taking down during the cone repair. Furthermore, this patch should be sutured above the TV annulus, and in the Todaro’s ligament at the septal area. These technical measures aim to facilitate the patch removal without damaging the TV leaflets or the atrioventricular node at the time of the Da Silva Cone procedure. In Figure 23, serial echocardiograms images demonstrate the cardiac evolution of a neonatal Ebstein submitted to the Starnes procedure and later to the Da Silva Cone repair.

Figure 23.

Serial echocardiograms show cardiac evolution in a four-chamber view. (a, b) Preoperative image shows typical, severe Ebstein’s anomaly morphology, with enlarged right heart chambers, and severe downward displacement of septal and inferior leaflets. The ventricular septum is shifted to the left, compressing the left ventricle. (c, d) Postoperative image after the Starnes procedure shows diastolic flow across the fenestration of the right ventricle exclusion patch (FP). Here, the ventricular septum (S) is shifted to the right (arrow); this reduces the area for the right ventricle and provides more space for the left ventricle, which increased in volume and assumed a globular shape. (e, f) Image acquired 3 weeks after biventricular repair shows the results of the Da Silva cone technique; the right ventricle is a good size, and the ventricular septum is in a well-balanced position. (e) The now anatomically positioned tricuspid valve presented good inflow and (f) mild to moderate regurgitation. AL = anterior leaflet of the tricuspid valve, RV = right ventricle, LV = left ventricle, FP = fenestrated polytetrafluoroethylene patch, and S = ventricular septum (Figure 23c with permission from reference [70].

8. Postoperative care

8.1 Hemodynamic management

Neonates may experience low-cardiac-output syndrome after surgical palliation for Ebstein’s anomaly. Inotropic support and afterload reduction for support of right ventricular and left ventricular function are necessary. Reduction of right ventricular afterload by decreasing pulmonary vascular resistance protects right ventricular strain and reduces hemodynamically significant tricuspid valve regurgitation. Neonatal patients with Ebstein’s anomaly who undergo single ventricular palliation may develop relative pulmonary hypertension or maintain elevated pulmonary vascular resistance and may benefit from inhaled nitric oxide and the use of muscle relaxants, in combination with pain control and sedation. In neonate surgical intervention, leaving an open sternum immediately after cardiopulmonary bypass facilitates ventilation at lower mean airway pressures and decreases right ventricular afterload. The sternum can be closed once improved myocardial function and a decrease in edema have been established.

8.2 Left ventricle

Even without associated left ventricular morphological abnormalities, left ventricular function may be compromised due to compression from a dilated atrialized right atrium (Figure 3b). Angiographic analysis of 26 patients with Ebstein’s anomaly demonstrated seven patients with a decrease in left ventricular diastolic volume (LVEDV <60 ml/m²); 12 patients had increased LVEDV (>80 ml/m²). Eight patients 29 (31%) either with normal or increased LVESV had decreased left ventricular ejection fraction in this study. Patients with a decrease in LVESV had normal left ventricular ejection fraction in this study [71]. Abnormalities of left ventricular morphology involving the myocardium or valves were noted in 39% of Ebstein’s anomaly [71], with 18% of patients demonstrating an association with left ventricular non-compaction [72]. Mitral valve prolapse, bicuspid aortic valve, and mitral valve dysplasia, as well as left ventricular systolic dysfunction (7%) and diastolic dysfunction (34%), can be associated with Ebstein’s anomaly [72]. A hemodynamically significant left ventricular outflow tract obstruction secondary to the systolic anterior motion of the mitral valve and severe mitral regurgitation was noted in a 52-year-old patient following tricuspid valve replacement and was resolved with esmolol administration [73]. Using three-dimensional models, a global or regional decrease in left ventricular ejection fraction (LVEF) was noted in patients with Ebstein’s anomaly (LVEF 41 ± 7% VS 57 ± 5%) [74]. In addition, tricuspid regurgitation is negatively correlated with the left ventricular ejection fraction by cardiac magnetic resonance imaging [75]. Rarely, non-apex forming left ventricular anatomy is associated with Ebstein’s anomaly, in which, heart transplantation is the only surgical option [76].

8.3 Arrhythmia

The downward displacement of the septal leaflet of the tricuspid valve is associated with direct muscular connections in the septal atrioventricular ring resulting in a potential connection for an accessory atrioventricular pathway [77]. Accessory pathways are noted in 10–36% of patients with Ebstein’s anomaly [78, 79, 80] and most accessory connections are located around the orifice of the malformed tricuspid valve [45, 81]. Delayed ventricular activation with the appearance of a right bundle branch block pattern can be seen in up to 93% of patients with Ebstein’s anomaly [80]. In a series of 52 patients with Ebstein’s anomaly from Mayo clinic, 34 patients (65%) had arrhythmias preoperatively (supraventricular tachycardia, atrial fibrillation, ventricular arrhythmias, and high-degree atrioventricular block) with perioperative and postoperative arrhythmias noted in 42% of the patients (14 patients had atrial tachyarrhythmia and eight had ventricular arrhythmias) s [82]. Maintenance of sinus rhythm is important to maintaining adequate cardiac output and may necessitate the use of epicardial pacing postoperatively.

8.4 Respiratory management

Tanaka et al. reported lung autopsy results from four neonates with Ebstein’s anomaly or tricuspid valve dysplasia. Lung hypoplasia or immaturity was not seen in full-term neonates with tricuspid abnormalities unless patients had a concomitant diaphragmatic hernia [83]. Despite an increased cardiothoracic ratio to 92% [83], surgical intervention to relieve tricuspid regurgitation and atrial plication may improve respiratory function by decreasing cardiomegaly and associated lung compression. Strategies to reduce pulmonary vascular resistance and minimize postoperative right ventricular distention and tricuspid regurgitation include the use of supplemental oxygen, inhaled nitric oxide, and ventilation to minimize hypercarbia. Early extubation, if feasible, will reduce intrathoracic pressure and right ventricular afterload.

9. Summary

Ebstein’s malformation is a condition that results from failure of the septal and inferior leaflets of the tricuspid valve to delaminate from the myocardial wall of the right ventricle which in turn results in the hinge point of the tricuspid valve being located within the right ventricle and not at the annulus. Furthermore, there is variability in the extent to which this failure to delaminate has on the heart. The effects may be limited when this anomaly is mild, but in hearts with more severe Ebstein’s anomalies, the rotational appearance of the hinge point of the tricuspid valve is more evident. The clinical presentations vary widely secondary to the abnormal morphology and the tricuspid valve and right ventricle as well as the associated heart defects. Neonatal Ebstein’s anomaly is continuous to be challenging. With the improvement in diagnostic methods, surgical treatment, and pre and postoperative care, the patients with a severe form of Ebstein’s anomaly still have a chance to undergo two-ventricle repair with good long-term outcomes.

Acknowledgments

The authors thank Miss Olivia Phillips for her computer assistance in preparing the figures.

Disclosure

The contributing Authors declare no competing interests in this article.