Both the origin of the tricuspid valve from the AV ring and its chordal attachments within the RV are malpositioned, and the leaflets are malformed. The leaflets are either enlarged or reduced in size and are frequently dysplastic (thickened and distorted). These deformities vary widely in severity ( Table 48.1 ). In the mildest forms, the valve is functionally near normal ; in the fully developed syndrome, tricuspid function is severely compromised. Displacement of the origin of the leaflets from the AV ring is reasonably constant. The septal leaflet appears always to be affected, the inferior (posterior) leaflet nearly always, and the anterior leaflet least affected ( Fig. 48.1 ). As noted by Anderson and colleagues, when both the septal and inferior leaflets are displaced, the point of maximum displacement is usually at the commissure between them. Thus, the functional tricuspid anulus is rotated apically and anteriorly toward the right ventricular outflow tract ( Fig. 48.2 ). In the few cases in which the anterior leaflet is displaced, the commissural area between it and the septal leaflet, attached to the right trigone at the point of penetration of the bundle of His, remains in normal position (see Fig. 48.1 ). In many patients, the apparent displacement is due to adherence of the base of the leaflet to the right ventricular endocardium (see Table 48.1 and Fig. 48.1 ). Adherence of leaflet tissue to the underlying myocardium is thought to represent a “failure of delamination” during development. This failure effectively moves the hinge points of the septal and inferior leaflets (the functional anulus) into the ventricular cavity.

Autopsy specimens of Ebstein anomaly with varying degrees of tricuspid valve deformity. Right atrium and right ventricle have been opened. (A) Site of true atrioventricular ring is marked by dashed line between arrows. All three leaflets are enlarged and elongated (anterior leaflet is poorly displayed). Septal leaflet is completely adherent to the ventricular septal surface and has abnormal distal chordal attachments, as does posterior leaflet. Note normal leaflet origin at right trigone (anteroseptal commissure). (B) Septal leaflet origin is displaced well downward into the ventricle, and leaflet tissue is diminutive and dysplastic. Posterior leaflet is adherent from the ring to a point marked with a large asterisk. Anterior leaflet origin is normal, its belly is mildly elongated and cleft, and there are multiple short chordal attachments. (C) Septal leaflet is absent except for a strand of fibrous tissue. Anterior leaflet origin is downwardly displaced (except at right trigone), as is the posterior leaflet origin. Darkened, bruised portion of ventricular wall is thinned, atrialized ventricle. (D) Elongated anterior and posterior leaflets originating normally from ring (arrow) but with poor commissural development. Central part of the distal anterior leaflet edge is completely fused to a broad muscle group on the right ventricular free wall; adjacent to this are thickened, short chordae. Septal leaflet is not visible. A, Anterior tricuspid valve leaflet; At, atrialized ventricle; CoS, coronary sinus; P, posterior tricuspid valve leaflet; S, septal tricuspid valve leaflet.

Functional tricuspid valve anulus in Ebstein anomaly. (A) Normal proximal tricuspid attachments at atrioventricular junction (circular dotted line) and direction of hinge line (square dotted line) . Displacement of valve orifice is rotational (flat arrow) . (B) Location of functional orifice of the abnormal valve (black ovals) as observed in the series of hearts examined by Schreiber and colleagues. ARV , Atrialized right ventricle; CS , coronary sinus; IVC , inferior vena cava; RA , right atrium; SVC , superior vena cava; TRV , true right ventricle.

The septal or inferior leaflet may be partially absent, in which case the belly of the leaflet is small or absent (see Fig. 48.1 ). The inferior leaflet is more often elongated than reduced in size (see Table 48.1 ), due in part to lack of a commissure between the inferior and anterior leaflets. This was the case in 8 of 15 hearts examined at autopsy at Green Lane Hospital, Auckland, New Zealand. The septal-inferior leaflet commissure may also occasionally be absent. Leaflet enlargement and elongation are characteristic of the anterior leaflet, which has been described as sail-like. The leaflet is usually diffusely thickened or ridged and occasionally consists partly of muscle. All the leaflets are frequently dysplastic, and isolated accessory leaflets may occur.

Distal leaflet attachments are variable and usually abnormal. Displaced and dysplastic inferior and septal leaflets frequently have multiple short chordae connecting to multiple small papillary muscles (see Fig. 48.1 ). The sail-like anterior leaflet may also have multiple short chordae arising around most of its free edge, binding it relatively closely to the septum and occasionally to the free wall, or the leaflet edge may be directly adherent to the anterior papillary muscle and moderator band or the posterior edge of the septal band. Presence of a free anterior leaflet is an important morphologic detail, because it greatly increases the likelihood of a successful repair. Leaflet fenestrations are common, with the opening typically guarded by a single papillary muscle, which gives rise to chords that attach to the periphery of the fenestration.

If the entire free margin of the leaflets is adherent and imperforate, (i.e., a linear attachment), one variety of tricuspid atresia is produced (see Chapter 52 ). ^, When the adherence is partial, the large anterior leaflet produces a variable degree of stenosis between the portion of ventricle proximal to it (atrialized ventricle) and that distal to it (functional or ventricularized ventricle), because blood can pass only between openings that remain between the leaflet margin and ventricular wall (or through the commissures when these are present) ( Fig. 48.3 ). Stiffness of the anterior leaflet can contribute to stenosis.

Cineangiogram in right anterior oblique projection of Ebstein anomaly. Injection is into a large atrialized right ventricle, demonstrating dome formed by the fused leaflets. Free reflux is present into the right atrium (RA) through atrioventricular ring (arrows). Relatively small functional (ventricularized) ventricle is poorly outlined because the displaced valve is stenotic (virtual tricuspid atresia). A, Atrialized portion of right ventricle; F, functional portion of right ventricle.

Although important stenosis is uncommon, most Ebstein valves are regurgitant, often severely so ( Fig. 48.4 ). This is contributed to by marked dilation of the true tricuspid anulus and the RV, as well as by morphologic abnormalities of the tricuspid valve.

Cineangiogram in right anterior oblique projection of neonate with pulmonary atresia and Ebstein anomaly. Injection was into the right ventricle, but the catheter has recoiled into the right atrium. Curved margin (black arrowheads) represents a dome formed by abnormally tethered distal edges of tricuspid leaflets. This margin separates the atrialized ventricle from functional ventricle. There is severe tricuspid regurgitation. Normally positioned atrioventricular ring is readily identified (white arrow). A, Atrialized portion of right ventricle; F, functional portion of right ventricle.

The functional tricuspid orifice is determined by the hinge points of the valve leaflets, which rotate around the aortic root. The resultant functional valve orifice resides at the junction of the inlet and apical trabecular portions of the RV. We emphasize Anderson’s focus on this rotational understanding of Ebstein anomaly to differentiate it from tricuspid valve dysplasia, which is often mistaken for Ebstein anomaly.

Rotational displacement of the tricuspid valve divides the RV into proximal (atrialized) and distal (ventricularized) portions. The proximal portion lies between the true tricuspid anulus and the valve attachment and comprises a variable portion of the posterior and inferior (diaphragmatic) aspects of the ventricular cavity (see Figs. 48.3 and 48.4 ). The right coronary artery denotes location of the true tricuspid anulus.

The proximal portion is atrialized in about one-fourth of hearts in which the inferior and septal leaflets are severely displaced ( Fig. 48.5 ). This atrialized portion of the ventricular wall is dilated. Uncommonly, it is so thin as to seem aneurysmal, in which case it is largely fibrous tissue, and the endocardium is smooth and nontrabeculated. When very thin, it moves paradoxically (dyskinetic) during ventricular systole and may also expand during atrial systole. Its electrical potentials are ventricular, but its pressure pulse has an atrial contour. More commonly, the wall of the atrialized portion is thicker than this and contains variable amounts of muscle.

Morphology of Ebstein anomaly. This image at operation shows typical EA. Septal and posterior leaflets are displaced below tricuspid anulus and are fused to endocardium of the right ventricle, producing an atrialized portion. Anterior leaflet of the tricuspid valve is enlarged and sail-like.

The functional ventricularized portion of the RV lies distal (downstream) to the displaced valve and is therefore smaller than the normal RV. However, this feature is modified by right ventricular dilation, which is an almost constant finding. The functional portion consists of the infundibulum (conus), trabeculated apex, and that portion of the ventricle beneath the large anterior cusp (anterolateral recess) ( Figs. 48.6 and 48.7 ).

Right anterior oblique (A) and left anterior oblique (B) cineangiogram frames of Ebstein anomaly. Injection was into the outflow portion of the functional (ventricularized) right ventricle, which also extends around the anterior and rightward free-wall aspects of the atrialized portion to form the anterolateral recess. Apical portion of the functional ventricle fills poorly and is superimposed on the atrialized portion in the left anterior oblique view. a, Apical portion of functional right ventricle; A, atrialized portion of right ventricle; I, outflow portion of the functional right ventricle; PT, pulmonary trunk; R, anterolateral recess.

Right anterior oblique cineangiographic frames of Ebstein anomaly. Injection was into the right ventricular apex. (A) Early frame showing reflux through displaced leaflets into atrialized ventricle. Deep notch (arrow) represents attachment of a dysplastic posterior leaflet to inferior wall. (B) Later frame showing more extensive filling of atrialized ventricle and right atrium (RA) . X marks the position of the true atrioventricular ring. A, Atrialized right ventricle.

Ebstein anomaly is more than a valve abnormality, in that the RV has an underlying myopathy. The dilated functional ventricle is usually thinner walled than normal and contains fewer muscle fibers. Anderson and Lie suggested there may be a congenital paucity of myocardial cells in the RV, such that dilation of both portions of the ventricle is part of the developmental anomaly rather than entirely its hemodynamic consequence.

In 1988, Carpentier proposed a classification system based on size of the functional RV and adequacy of the anterior leaflet for repair ^, :

• •

  Type A: volume of true RV is adequate.

• •

  Type B: a large atrialized component of RV is present, and the anterior leaflet of tricuspid valve moves freely.

• •

  Type C: movement of anterior leaflet is severely restricted and may cause obstruction of right ventricular outflow tract.

• •

  Type D: RV is nearly completely atrialized, except for a small infundibular component.

The right atrium is enormously dilated in advanced cases. There is usually an interatrial communication (60% of autopsy specimens, 42% at catheterization, and 21 of 22 surgical cases in Watson’s collective review), most commonly a patent foramen ovale, although an atrial septal defect (ASD) of any type may be present. Interatrial communication was present in 94% of patients at operation in the series reported by Danielson and colleagues. Rarely, an ostium primum AV septal defect coexists.

The bundle of His and AV node lie in their usual locations, although the right bundle and node may be compressed by thickened endocardium (a possible explanation of the frequent right bundle branch block pattern in the electrocardiogram). ^{, , ,} WPW syndrome is present in about approximately 14% of persons with Ebstein anomaly. ^,

Monibi and colleagues and Ng and colleagues report that abnormal left ventricular contraction and contour and mitral valve prolapse are frequently present. ^, Marked dilation of the RV produces leftward septal shift and compression and posterior displacement of the left ventricle (LV). Daliento and colleagues studied nine autopsied hearts and found the ventricular septum normal in six and thin in three, which could account for the exaggerated leftward diastolic movement observed by angiography in 24 of 26 patients. Severe leftward displacement produced a “banana” appearance of the LV. Regional left ventricular wall motion abnormality was observed in 67% of patients. In a Mayo Clinic experience of over 500 surgical patients with Ebstein anomaly, 9% had moderate or severe left ventricular dysfunction. When mitral valve prolapse is present, the valve is frequently nodular and thickened. ^{, , ,} A Mayo Clinic study of 106 patients identified left ventricular abnormalities in 39%, of whom 18% had left ventricular dysplasia resembling noncompaction.

In severe Ebstein anomaly associated with fetal and neonatal distress or death, both lungs are usually hypoplastic but otherwise normal. The hypoplasia is secondary to gross cardiomegaly from severe tricuspid regurgitation.

An ASD is present in 80% to 95% of patients with Ebstein anomaly. ^, Pulmonary atresia or stenosis may be present in up to one-third of autopsied hearts (see Chapter 36 ). Others include ventricular septal defect, tetralogy of Fallot, patent ductus arteriosus, transposition of the great arteries, coarctation of the aorta, and congenital mitral stenosis. ^{, , ,}

In congenitally corrected transposition with atrial situs solitus, the tricuspid valve lies within a left-sided, systemic, morphologic RV. Although 30% of these left-sided valves are regurgitant, this is frequently due to Ebstein anomaly. ^, This Ebstein anomaly differs from the usual right-sided form in that dilation of the AV ring and separation of the morphologic RV into atrialized and ventricularized portions are uncommon. The anterior leaflet is also less prominent and may be cleft (see Chapter 47 ).

Three primary pathophysiologic features predominate in patients with Ebstein anomaly:

• •

  Right ventricular abnormalities

• •

  Tricuspid valve abnormalities

• •

  Accessory conduction pathways (WPW syndrome)

Their severity determines secondary pathophysiologic features, clinical presentation, and natural history.

Breathlessness in association with cyanosis, severe cardiomegaly, and often heart failure may appear during the first week of life. However, many patients have milder symptoms and do not present until later in life. Nonetheless, objective exercise testing shows that their functional capacity is less than normal. Oxygen saturation at rest is a major predictor of exercise tolerance. Mild dyspnea and fatigue may become evident in childhood or early adult life, or more severe symptoms and signs of various types may develop. If heart failure develops, the patient becomes severely limited by breathlessness and fatigue.

Cyanosis is a common sign of Ebstein anomaly, occurring in more than half of patients and severe in about one-third. It may appear at birth, but in most patients, onset is in infancy or early childhood.

Palpitations caused by various types of arrhythmia are also common. Severe arrhythmic symptoms are frequent in patients of all ages and may be disabling. WPW syndrome is the best known type of arrhythmia, but less specific types of supraventricular tachycardias are more common. Numerous electrophysiologic abnormalities have been identified, which no doubt account for the frequent occurrence and persistence of arrhythmic symptoms even after operation. ^, Symptoms are more severe when there are important associated cardiac anomalies.

A malar flush, similar to the so-called mitral facies, was noted by Ebstein’s colleague and occurs in about one-third of patients. It is unrelated to cyanosis or polycythemia or to cardiac output.

The left anterior chest is often prominent in association with marked cardiomegaly, and there may be a systolic thrill along the left sternal edge originating from the tricuspid valve. Characteristically, the precordium and apex remain quiet despite marked cardiomegaly. Jugular venous pressure is generally unremarkable and rarely suggests tricuspid regurgitation or stenosis, even though free tricuspid regurgitation is revealed by imaging studies. This is related to the large size and compliance of both the right atrium and atrialized RV, as well as the low right ventricular and pulmonary artery pressure. Congestive hepatosplenomegaly is commonly observed and may eventually lead to hepatic fibrosis.

On auscultation, the most consistent finding is wide splitting of the first sound with accentuation of the delayed component caused by closing (or termination of motion ^, ) of the large anterior tricuspid leaflet. Delayed tricuspid valve closure is probably mechanical rather than related to right bundle branch block, although Crews and colleagues considered it correlated with the latter. ^, The large anterior leaflet is also responsible for an opening snap in diastole, and there may be an atrial fourth sound. The pulmonary component of the second sound is delayed and soft (in relation to the right bundle branch block) or absent when pulmonary artery pressure is low. A pansystolic murmur maximal at the lower left sternal edge is due to tricuspid regurgitation and is heard in about one-third of patients. Finally, there is usually a diastolic murmur, often low pitched and sometimes scratchy in quality, commencing with the opening snap and sometimes augmented by the fourth sound. The diastolic murmur is presumably due to movement of blood across the malformed tricuspid orifice.

In classic Ebstein anomaly, the chest radiograph shows marked cardiomegaly with a rounded or boxlike cardiac contour beneath a narrow pedicle ( Fig. 48.8 ). In the posteroanterior view the whole of the silhouette is then formed by the right atrium and RV, and because of their minimal excursion and the normal or oligemic lung fields, the silhouette has a peculiarly sharp edge. However, as with other features of the disease, there is wide variation in heart size. In a few cases, it remains normal; in most, it is only moderately enlarged.

Chest radiograph of a 12-year-old girl with classic Ebstein anomaly.

A right bundle branch pattern together with a relatively low-amplitude R wave in right-sided chest leads and right atrial hypertrophy are characteristic of the anomaly. According to Kumar and colleagues, height of the P wave varies inversely with arterial oxygen saturation (r =.82, P <.001). In addition, the taller the P wave, the shorter the survival time ( P <.001). Right ventricular hypertrophy does not occur in uncomplicated Ebstein anomaly, and inverted T waves in leads V ₁ to V ₄ are fairly common. Using intraluminal electrode catheters, Kastor and colleagues demonstrated prolonged intra–right atrial and infranodal conduction in patients with a large right atrium and well-defined atrialized ventricle.

In approximately 14% of patients, the electrocardiogram shows type B (right-sided) WPW syndrome. In any cyanotic patient with this type of preexcitation, Ebstein anomaly should be considered. Supraventricular arrhythmias occur in more than half of patients, and they may be paroxysmal and recurrent. Paroxysmal atrial tachycardia, atrial fibrillation, and nodal rhythm can all occur, as can first-degree heart block. Serious ventricular arrhythmias resulting from right ventricular dilation may also occur.

Two-dimensional echocardiography has become definitive for diagnosis and anatomic evaluation of Ebstein anomaly, ( Fig. 48.9 ). It is possible to identify Ebstein anomaly by the characteristic degree of displacement of the septal leaflet of the tricuspid valve (>8 mm · m ^{− 2} ), variable degrees of leaflet tethering (i.e., failure of delamination), and the presence of an elongated, redundant anterior tricuspid valve leaflet. ^, The feasibility of tricuspid repair rather than replacement can be determined with this method of imaging. A right-to-left atrial shunt and tricuspid regurgitation can be demonstrated using Doppler color flow interrogation.

Two-dimensional echocardiogram of Ebstein anomaly. There is characteristic displacement of the hinge point of the septal leaflet below natural tricuspid anulus and adherence to septal wall. Anterior leaflet is elongated.

Historically, M-mode echocardiography usually demonstrated delayed tricuspid valve closure and displacement of the tricuspid valve to the left. According to Giuliani and colleagues, the greater the delay in tricuspid valve closure, the more severe the disease. Wide excursion of the anterior leaflet, a decreased E-F slope, increased right ventricular dimensions, and paradoxical septal motion can also be demonstrated.

Currently, cardiac catheterization and cineangiography are required only when specific hemodynamic details need to be identified, or in patients over about age 40, when the coronary tree should be examined.

In the past, cardiac catheterization showed that the mean right atrial pressure is often modestly elevated, and the pressure pulse may have either a dominant a or v wave. These correlate poorly with the degree of tricuspid regurgitation or stenosis. An additional s wave preceding the v wave and interrupting the c wave is said to indicate tricuspid regurgitation. ^{, ,} The right atrial waveform is also recorded in the atrialized portion of the RV so that the tricuspid valve is noted to be displaced well toward the left of the spine. An electrode catheter may define the position and size of the atrialized right ventricular chamber. ^, Right ventricular systolic pressure is normal or low, and right ventricular end-diastolic pressure is frequently elevated, more so when there is the syndrome of chronic heart failure. It is uncommon to record an important gradient across the tricuspid valve, although Takayasu and colleagues noted this in 8 of 26 cases and considered that stenosis could still be important in its absence. ^,

When there is an interatrial communication, the shunt through it is usually right to left in association with systemic arterial desaturation and a reduced pulmonary blood flow ( Q ˙ p ). The right-to-left shunt can be quantified by indicator dilution. The shunt may occasionally be left to right, and the resultant increase in Q ˙ p may be associated with heart failure. Direction of shunting is no doubt influenced by right ventricular compliance.

In the newborn with Ebstein anomaly, a functional pulmonary “atresia” can occur. Thus, a normal pulmonary valve may fail to open following a right-sided injection of contrast media because of the combination of massive tricuspid regurgitation, poor right ventricular contraction, and a high neonatal pulmonary vascular resistance with or without a large shunt at ductal level. High-quality imaging is therefore necessary to distinguish this situation from true pulmonary atresia.

Cineangiography (see Figs. 48.3 , 48.4 , 48.6 , 48.7 ) is usually diagnostic as long as there is important displacement and dysplasia of the septal or inferior leaflets. In the right anterior oblique projection, the conjoined inferior and anterior leaflets, and therefore the distal limit of the atrialized ventricle, can frequently be identified. Contrast media trapped beneath the inferior leaflet can indicate the degree of its adherence to, and level of its origin from, the diaphragmatic border of the RV, which may be notched at this point. The site of the true anulus is also visible more proximally. An injection into the functional RV enables tricuspid regurgitation to be assessed together with size and behavior of the functional ventricle. Angiography in left anterior oblique projection also permits visualization of the right-to-left shunt at atrial level, and any ventricular septal defects can be localized by left ventriculography.

Ebstein anomaly is a recognized cause of death in utero. ^{, ,} When severe tricuspid regurgitation accompanies Ebstein anomaly at birth, the elevated newborn pulmonary vascular resistance worsens it. Pulmonary blood flow may be ductal dependent. The resultant severe hypoxemia (right-to-left shunting through an ASD), coupled with marked right-sided heart failure, may also be accompanied by low cardiac output if the ASD is restrictive. This is because maintenance of normal cardiac output requires shunting at the atrial level through a nonrestrictive ASD. Low cardiac output may also result from abnormal ventricular interactions caused by paradoxical septal bowing and flattening of the LV. The hypoxemia may be aggravated by pulmonary dysfunction secondary to lung compression by marked cardiomegaly. Although lung hypoplasia has been suggested, ^, pathologic studies indicate that the lungs are rarely hypoplastic in surviving newborns but are instead compressed by the enlarged heart.

Celermajer and colleagues from Great Ormond Street identified neonates with good and poor outcomes based on a score (Celermajer Score or Great Ormond Street Ratio) ^, derived from echocardiographic measurements of the right atrium, RV, left atrium, and LV. The score is calculated from a four-chamber echocardiographic view in which the combined area of the anatomic right atrium plus atrialized RV is divided by the sum of the areas of the functional (nonatrialized) RV, left atrium, and LV ( Table 48.2 ). The outlook is generally dismal for patients with Celermajer grades 3 or 4 ^, (Ratio >1; severe EA; Fig. 48.10 ). Importantly, patients with Ebstein anomaly who survive after presentation early in life have a good chance of long-term survival.

Changes in tricuspid anular dimension with progression of rotational tricuspid valve displacement from normal (left panel) to moderate (middle panel) to severe (right panel) . Dotted line indicates functional tricuspid placement with increasing severity of EA.

(From Malhotra SP, Petrossian E, Reddy VM, et al. Selective right ventricular unloading and novel technical concepts in Ebstein’s anomaly. Ann Thorac Surg . 2009;88:1975-1981.)

Many studies have probably underestimated the incidence and severity of this entity in neonates. The review by Vacca and colleagues of 108 clinical or autopsy cases reported between 1866 and 1957 recorded only two patients younger than 1 month. In Watson’s collective review of 505 cases, only 35 (7%) were younger than 1 year (half were younger than 1 month). In Bialostozky and colleagues’ review of 65 patients, neonates were not included. In a Mayo Clinic series, only 10 of 67 patients were diagnosed in infancy. In a Boston Children’s Hospital series, 12 of their 55 patients (22%) were seen during the first week of life, and 34 (64%) were younger than 2 years. Eleven of the 34 died early. These series must have been in some way selective and therefore are not useful in assessing natural history. In contrast, Schiebler and colleagues’ earlier study from the Mayo Clinic found that 12 of 23 patients presented during the neonatal period, and of these, 5 died. Roberson and Silverman reported that among 16 consecutive patients diagnosed in utero or presenting during the first 3 days of life, 7 died before age 3 months; all had severe right ventricular and tricuspid morphologic abnormalities. In the 40-institution administrative registry of the Pediatric Health Information System (PHIS), of 464 neonates diagnosed with Ebstein anomaly from January 2003 to January 2008, 415 with complete data, mortality during initial hospitalization among 257 (62%) managed medically was 22% (56/257; CL 19%–25%).

Presentation in infancy is associated with less risk of death and milder symptoms than occur with neonatal presentation ( Fig. 48.11 ), although some studies suggest an increased mortality until presentation is beyond about 6 months. ^{, ,} Beyond this age, Watson’s series indicates a prognosis similar to that of older children. He states that “whereas 72% of those under 1 year were in heart failure, 71% of the children and adolescents had little or no disability.”

Survival of patients with Ebstein anomaly, total and stratified according to age at presentation. Numbers of patients at risk are noted. P value for difference between the two stratified curves is.01.

(From GLH group.)

Patients presenting after infancy often have mild symptoms. Prognosis is generally good, consistent with less severe right ventricular and tricuspid valve pathophysiology. Patients presenting in adult life are often acyanotic and have a normal-sized or mildly enlarged heart. However, even these patients, who report few symptoms, have clearly definable abnormalities. Without preexcitation, nearly half have episodic supraventricular tachyarrhythmias, although these usually produce few symptoms. Exercise tolerance measured by objective testing is often reduced. ^{, , ,} The degree of tricuspid regurgitation does not correlate with symptoms, but as time passes, left ventricular dysfunction often appears as symptoms develop.

Death in this group of patients is often due to paroxysmal embolism or paroxysmal supraventricular tachycardia, with heart failure appearing either much later or not at all. An atrial level communication increases the risk of paradoxical embolism, brain abscess, and sudden death.

Heart failure is the mode of death in somewhat less than half of patients who die of causes related to their heart disease after the neonatal period. ^, Sudden death, presumably caused for the most part by arrhythmias other than those associated with WPW, occurs in about 60% (CL 43%–77%) of these patients. ^{, ,} Sudden death correlates with marked cardiomegaly, rather than with New York Heart Association (NYHA) status. Cerebral abscess and paradoxical emboli account for most of the remaining deaths, particularly in patients older than about 50 years. ^, Infective endocarditis is rare.

The usual preparations are made for operation, anesthetic management (see Chapter 4 ), and cardiopulmonary bypass (CPB) (see Chapter 2 ). Before commencing CPB, the atrialized portion of the RV is assessed, noting particularly whether it moves paradoxically.

CPB is established using two venous cannulae, and the degree of hypothermia is individualized and may range from 25°C to 34°C. The aorta is occluded, and tourniquets secured around the venae cavae and cannulae. Cold cardioplegia may be administered directly into the aortic root or into the coronary sinus after the atrium is opened (see “ Technique of Retrograde Infusion ” in Chapter 3 ). The right atrium is incised parallel to the AV groove. A sump-sucker is placed across the atrial septum into the left atrium.

The anulus is suspended at 10:00 and 2:00 and the atrial septum and tricuspid valve are examined ( Fig. 48.12 ). The anterior leaflet of the tricuspid valve is studied with particular care, because successful repair of a regurgitant tricuspid valve relies on it, particularly if the repair strategy is a monocusp technique. The anterior leaflet is rarely displaced into the RV. Extreme thickening (muscularization) of the anterior leaflet, and particularly the dense attachment of its free edge to the underlying right ventricular endocardium, makes successful repair more challenging.

Morphology of interior of right atrium in Ebstein anomaly at operation. Septal and posterior leaflets of the tricuspid valve are adhered to the septum and right ventricular (RV) wall. Downward displacement of the tricuspid valve divides right ventricle into a proximal atrialized portion and a distal ventricularized portion. Anterior leaflet is enlarged and elongated, described as sail-like. There is a foramen ovale type of atrial septal defect. Coronary sinus, atrioventricular node, and bundle of His are in their usual locations.

Tricuspid valve repair with ASD closure (or subtotal closure) is the preferred operation. The earliest repairs were designed to convert the tricuspid valve into a monoleaflet valve using the anterior leaflet to establish valve competence. The most important features that predict successful repair are a mobile, free leading edge of the anterior leaflet and attachment of more than 50% of it at the anatomic tricuspid anulus. A variety of maneuvers have been used to mobilize and extend this leading edge, with or without plication of the atrialized portion of the RV.

The method devised by Danielson and colleagues was the most popular early repair. ^, It plicates the atrialized portion of the ventricle, narrows the tricuspid orifice in a selective manner, and results in a monoleaflet valve that coapts with the ventricular septum or diminutive septal leaflet and is usually competent or nearly so. A modification of the Danielson method in which the tricuspid valve anulus is remodeled by an anuloplasty band is shown in Fig. 48.13 . Dearani and colleagues have also recommended moving the anterior leaflet closer to the ventricular septum by mobilizing the major papillary muscle(s) supporting the anterior leaflet to a position closer to the septum. This is accomplished by placing a pledgeted Gore-Tex mattress suture(s) from the papillary muscle to a corresponding septal papillary muscle or septal trabeculation ( Fig. 48.14 ) (Dearani modification of Sebening stitch) or in some cases directly to the ventricular septum (original Sebening stitch) ^, ( Fig. 48.15 ). The original Sebening stitch strategy is most useful in neonatal tricuspid repair of EA.

Repair of regurgitant tricuspid valve in Ebstein anomaly using a modification of the Danielson method. ^{, ,} (A) A series of pledget-reinforced mattress sutures are placed at base of the septal and posterior leaflets of tricuspid valve. Stitches are continued to plicate atrialized portion of right ventricle (RV) up to the natural location of the valve anulus. Stitches are passed through a Carpentier anuloplasty ring. Atrial septal defect is closed by pericardial patch. (B) Plication sutures are tied over anuloplasty ring to remodel the anulus and obliterate atrialized portion of the RV to complete the repair. Large anterior leaflet occludes the atrioventricular orifice.

Modified Sebening suture; two pairs of 5-0 pledgeted Gore-Tex chords are placed between a ventricular septal trabeculation or septal papillary muscle (below) and anterior papillary muscle (above). The sutures are secured over a Hegar dilator to avoid excessive tension and dehiscence; this is effectively artificial chordae from the ventricular septum to the anterior papillary muscle.

Diagram of modified Mayo Clinic method of tricuspid valve repair technique used for Ebstein anomaly. (A) Two papillary muscles arise from free wall of right ventricle, with short chordal attachments to leading edge of anterior leaflet. Septal leaflet is diminutive and only a ridge of tissue. Posterior leaflet is not well formed and is adherent to underlying endocardium. A small patent foramen ovale is present. (B, C) Base of each papillary muscle is moved toward ventricular septum at the appropriate level with horizontal mattress sutures backed with felt pledgets. Patent foramen ovale is closed by direct suture. (D) Posterior angle of tricuspid orifice is closed by bringing right side of anterior leaflet down to the septum and plicating the nonfunctional posterior leaflet in the process. (E) A posterior anuloplasty is performed to narrow the diameter of tricuspid anulus; the coronary sinus marks posterior and leftward extent of anuloplasty. (F) An anterior purse-string anuloplasty is performed to further narrow tricuspid anulus. This anuloplasty stitch is tied down over a 25-mm valve sizer in an adult to prevent tricuspid stenosis. (G) Completed repair that allows anterior leaflet to function as a monoleaflet valve.

(From Dearani and colleagues. Used with permission of Mayo Foundation for Medical Education and Research.)

An alternative is the Carpentier repair, in which the anterior leaflet is detached from the anulus and surgically mobilized, i.e., dividing all attachments between the anterior leaflet and underlying myocardium. This is referred to as “surgical delamination.” The atrialized ventricle is plicated vertically ( Fig. 48.16 ). The anterior leaflet is advanced and reattached to the true anulus.

Repair of regurgitant tricuspid valve in Ebstein anomaly using the Carpentier method. (A) Three-fourths of the enlarged anterior leaflet and as much as possible of the posterior leaflet are detached from the anulus. Incision is continued to the point at which the valve begins to be displaced on the ventricular wall at the atrialized portion of right ventricle (RV). (B) Detached leaflet is everted to expose support mechanism. There is usually chordal fusion, which may be marked in some cases. Fenestrations are made in the support mechanism to lengthen chordae and relieve obstruction below leaflets. (C) Unique aspect of repair is placing pledget-reinforced plication stitches in atrialized portion of RV to create a vertical plication. Plication stitches are continued from base of leaflet attachment to ventricle to true anulus. Anulus is narrowed by this technique. A few stitches are placed in the floor of the right atrium. Plication stitches may be woven across the atrialized portion for better obliteration of this portion of the ventricle. (D) Detached portion of tricuspid leaflet is rotated clockwise to cover tricuspid orifice beyond plication and as far toward septum as it will reach comfortably. Leaflet is reattached to the anulus by continuous suture. (E) Repair is supported by a Carpentier anuloplasty ring, which also remodels the shape of anulus. It is attached to tricuspid anulus by a series of mattress sutures placed at the perimeter of anulus. These stitches are most easily placed before the anterior leaflet is reattached. A gap in the anuloplasty ring protects the conduction system from injury.

(From Carpentier A, Chauvaud S, Mace L, et al. A new reconstructive operation for Ebstein’s anomaly of the tricuspid valve. J Thorac Cardiovasc Surg . 1988;96:92.)

The most widely accepted contemporary technique that is considered a nearly anatomic repair has been proposed by da Silva and colleagues and termed the cone procedure . The cone reconstruction is nearly anatomic for the following reasons: (1) 360 degrees of leaflet-to-leaflet coaptation, (2) valve hinge point at true anulus, (3) plication of dyskinetic, atrialized RV, and (4) functional RV approaching normal size. The detailed steps of the cone procedure are shown and described in detail in Fig. 48.17 . The anterior and inferior leaflets are detached from the anulus as a single unit, surgically delaminated and mobilized from their anomalous attachments in the RV and rotated in a clockwise fashion to the mobilized septal leaflet. Side-to-side connections between all of the mobilized leaflet tissue are performed creating circumferential leaflet tissue without commissures that allows leaflet-to-leaflet coaptation. The rotated leaflets are reattached to the true anatomic anulus. The dilated anatomic anulus is plicated to match the size of the smaller, more normal-sized neotricuspid anulus. This original repair technique does not incorporate an anuloplasty band Fig. 48.17 A–H. Da Silva and Dearani both incorporate a longitudinal plication of the atrialized portion (i.e., vertical suture line begins toward the right ventricular apex and runs proximally toward the base of the heart and crosses the true anulus). Da Silva and colleagues recommend closing the foramen ovale in a valved fashion. It should be recognized that the “learning curve” for the cone reconstruction is challenging ( Fig. 48.18 ).

(A to H) Cone Repair for Ebstein Anomaly.

(A)The septal leaflet is displaced apically away from the true tricuspid valve anulus. Mobility of the anterior leaflet is usually best up under the right ventricular outflow tract and tethering most often begins in its mid-portion (around 12–1:00 o’clock as seen by the surgeon) and moving medially toward the inferior leaflet. The inferior leaflet has varying degrees of mobility that is dependent on the presence or absence of RV atrialization. The true tricuspid valve anulus is dilated. (B) The surgical mobilization of leaflet tissue begins by incising the anterior leaflet off of the anulus at 10 o’clock and extending the detachment in a clockwise manner all the way around the anulus until leaflet tissue ends. This is typically in the region of 2–3 o’clock and is dependent on the degree of development of inferior leaflet. The incision is then extended counterclockwise toward the anteroseptal commissure (around 7 o’clock). The dotted line marks the end of the anterior leaflet tissue with just a small portion of inferior leaflet tissue. The dotted line also represents a linear attachment of the leading edge of the anterior and inferior leaflets distally and should be incised along the dotted line all the way down to the distal most point of the anterior leaflet. All attachments (both fibrous and muscular) between the body of the leaflets and the free wall of the ventricle are surgically divided so that the only remaining attachments supporting the leaflet(s) are chordal attachments to the leading edge. (C) Surgical division of abnormal muscular and fibrous attachments are demonstrated here. There should be no attachments between the body of the anterior and inferior leaflets and the free wall of the right ventricle. The only attachments that persist after complete surgical mobilization (i.e., surgical delamination) are those chordal attachments to the leading edge of the anterior and inferior leaflets. The common mistake is failure to divide all attachments preventing proper leaflet coaptation! (D) After complete mobilization of the anterior and inferior leaflets, the septal leaflet is delaminated off the septum with a combination of scissor and knife dissection. The atrialized, non-trabeculated RV is demonstrated in this figure between the septal leaflet and the trabeculated RV. (E) After mobilization of the septal leaflet so that the only attachments are chordal support to its leading edge, the anterior and inferior leaflets are rotated clockwise to meet the mobilized proximal edge of the septal leaflet. This leaflet-to-leaflet approximation is done with interrupted figure-of-eight monofilament sutures to avoid a potential purse string effect. The circumferential leaflet tissue surrounding the atrioventricular junction has the appearance of a cone. The only natural commissure is the anteroseptal commissure. The decision to close this commissure to create a true circumferential cone is determined by the size of the distal orifice of the cone. (F) After the neotricuspid leaflet side-to-side approximations are complete it is evident that the neotricuspid valve orifice is quite a bit smaller than the original native tricuspid valve anulus. An intact supporting anterior papillary muscle is shown (ghosted in) behind the anterior leaflet in this diagram. (G) After the cone reconstruction but prior to leaflet anular reattachment, the atrialized RV is plicated. This is performed internally with two continuous running layers of monofilament suture beginning distally where atrialized RV begins and extending across the anulus and into the right atrium. Great care is taken not to compromise the right coronary artery. (H)The anteroseptal commissure is taken down. A side-to-side connection is performed between the anterior leaflet and the septal leaflet of the tricuspid valve. The valve size of the effective orifice corresponds to the size of the orifice at the distal aspect of the cone. Additional anular plication sutures are noted reducing the size of the dilated true anulus to match the smaller more “normal sized” neo tricuspid valve reconstruction. The neotricuspid valve reconstruction is then reattached to the true tricuspid valve anulus. The suture line for the septal leaflet reattachment is shifted to the ventricular side of the conduction tissue to avoid injury to it.

(From Dearani JA, Mavroudis C. Ebstein anomaly. In: Mavroudis C, Dearani J, eds. Atlas of Adult Congenital Heart Surgery . Cham: Springer; 2020.)

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