Tricuspid valve atresia

INTRODUCTION — Tricuspid valve (TV) atresia is a cyanotic congenital heart lesion that is characterized by congenital agenesis or absence of the TV, resulting in no direct communication between the right atrium and ventricle [1]. If untreated, TV atresia has a high mortality rate, with a survival rate as low as 10 percent at one year of age, depending on the type of TV atresia and the presence of other cardiac lesions [2,3].

The constellation of anatomic variants, physiology, clinical presentation, diagnosis, and management of TV atresia will be reviewed here.

EPIDEMIOLOGY — TV atresia is the third most common cyanotic heart lesion, with an estimated prevalence of 0.5 to 1.2 per 10,000 live births [4-7]. There is no difference in the incidence based on sex.

ANATOMY — Although TV atresia is characterized by the absence of the TV, there is a spectrum of anatomic variants based on the morphology of the atresia and the presence of other cardiac structural lesions.

Morphology of tricuspid valve atresia — Morphologic variation of TV atresia includes the following [8,9]:

●Muscular atresia is the most common form, accounting for approximately 80 percent of patients. In this subtype, there is a solid muscular floor to the right atrium, with a dimple in the expected location of the TV.

●Membranous atresia (approximately 10 percent), in which the atrioventricular portion of the membranous septum forms the floor of the right atrium.

●Valvular atresia (5 percent), in which tiny valve cusps are fused together.

●Ebstein subtype, in which there is both downward displacement and fusion of the TV leaflets into the right ventricle (RV) wall [10].

●Rarely, patients with atrioventricular canal defects will have atresia of the right atrioventricular valve when a leaflet of a common atrioventricular valve seals off the entrance to the RV.

Although all of the variants are hemodynamically similar, it is important to distinguish the valvular and Ebstein subtypes from the others because of differing surgical approaches. In patients with the Ebstein and valvular subtypes, the surgical approach entails excision of the malformed valve and prosthetic valve replacement, whereas in the other variants, surgical management consists of palliative interventions including the Fontan procedure. (See 'Surgical management' below.)

Associated cardiac lesions — Associated cardiac lesions are universally seen in patients with TV atresia. This was illustrated in a study of 225 consecutive patients with TV atresia cared for at a single Canadian tertiary center between 1971 and 1999 [11]. The following cardiac lesions and their relative frequency were observed:

●Atrial septal defect (100 percent) – In many cases, the atrial septal defect is a patent foramen ovale. The right atrium is typically enlarged and hypertrophied.

●Right ventricular hypoplasia (100 percent) – The RV is hypoplastic and often comprised of only the infundibular portion. The inflow portion of the RV can vary in size depending on the size of the ventricular septal defect (VSD).

●VSD (95 percent) – In TV atresia, muscular VSD is the most commonly observed type of VSD [12]. Malalignment VSDs occur with a lower frequency but may contribute to subarterial obstruction. VSDs can be large, small, or absent [8]. Spontaneous closure of the VSD has been reported and approximates the incidence of spontaneous closure of isolated VSDs [12]. (See "Isolated ventricular septal defects (VSDs) in infants and children: Anatomy, clinical features, and diagnosis", section on 'Natural history'.)

●Pulmonary outflow obstruction (75 percent) – Pulmonary blood flow can be restricted by the presence of a small VSD, pulmonary valve stenosis or hypoplasia, or severe hypoplasia of the right ventricular outflow tract (eg, pulmonary artery defects).

●Ventricular arterial discordance including transposition of the great arteries or double-outlet right ventricle (28 percent).

●Severe pulmonary artery hypoplasia or distortion (17 percent).

●Aortic or subaortic stenosis (11 percent).

●Aortic coarctation or interruption (8 percent) – Coarctation is frequently associated with transposition of the great arteries [2].

●Coronary anomaly (3 percent).

CLASSIFICATION — Several classification systems have been developed based on descriptions of the anatomic variants (eg, associated cardiac lesions and the morphology of atresia, described above) [8]. The most widely used schema divides TV atresia into three categories based on the anatomy of the great arteries (aorta and pulmonary artery) [8,13]. Subdivision within the first two categories is based on pulmonary blood flow, and the presence and size of a ventricular septal defect (VSD) is also used to categorize subtypes. Surgical management is generally based on the anatomy of the great arteries (table 1). (See 'Surgical management' below.)

●Type I (70 to 80 percent): Normal anatomy of the great arteries

•Subgroup a – Intact ventricular septum with pulmonary atresia

•Subgroup b – Small VSD with pulmonary stenosis or hypoplasia

•Subgroup c – Large VSD without pulmonary stenosis

●Type II (12 to 25 percent): D-transposition of the great arteries (see "D-transposition of the great arteries (D-TGA): Anatomy, clinical features, and diagnosis")

•Subgroup a – VSD with pulmonary atresia

•Subgroup b – VSD with pulmonary stenosis or hypoplasia

•Subgroup c – VSD without pulmonary stenosis

●Type III (3 to 6 percent): Malposition defects of the great arteries other than D-transposition of the great arteries (eg, truncus arteriosus, atrioventricular septal defects, and double-outlet right ventricle)

A variation of this schema subdivides type III based on variations in ventricular and arterial alignment and groups TV atresia with truncus arteriosus as type IV [4,8].

PATHOGENESIS — The pathogenesis of TV atresia is unknown. It is thought that most cases of TV atresia (muscular, membranous, and valvular subtypes) are derived from a similar disruption of normal development of the atrioventricular valves from the endocardial cushions and delamination of the ventricular myocardium. (See 'Morphology of tricuspid valve atresia' above.)

Genetics — In some cases, an underlying genetic defect may contribute to the disruption of the normal development of the TV. Although no specific gene defect has been identified, supporting evidence for a genetic contribution includes the following:

●Studies in mice with TV atresia have identified mutations in the FOG2 gene (also referred to as ZFPM2) [14]. The multi-zinc protein product of the FOG2 gene has a role in early cardiac development.

●Familial occurrence of TV atresia has been reported in three siblings, suggesting an autosomal recessive pattern of inheritance [15].

●Association with chromosomal and syndromic conditions including trisomy 18 and 21, chromosomal 8 deletion, and VACTERL association (vertebral anomaly, anal atresia, cardiac defect, tracheoesophageal fistula, and renal and limb abnormalities) [16].

PATHOPHYSIOLOGY — In TV atresia, the only exit of blood from the right atrium is through an interatrial communication. This obligate right-to-left atrial shunting is necessary for survival as it allows deoxygenated systemic venous blood to enter the left atrium and subsequently, the left ventricle (LV). As a result of the mixing of systemic and pulmonary venous blood in the left atrium, some level of cyanosis is always present (figure 1).

Pulmonary blood flow in patients with TV atresia depends on the anatomy of the great arteries and the presence and size of a ventricular septal defect (VSD) (table 1 and figure 1). (See 'Classification' above.)

●Type I TV atresia with normal anatomy of the great arteries:

•In patients with no VSD (subtype Ia), there is no pulmonary blood flow from the right ventricle (RV). A patent ductus arteriosus (PDA) is the only source of pulmonary blood flow. Systemic blood flow is derived directly from the LV.

•In patients with a VSD (subtypes Ib and Ic), the left-to-right flow of blood from the LV to RV across the VSD is the source of pulmonary blood flow. The size of the VSD and the degree of pulmonary stenosis dictate the amount of pulmonary blood flow, which in turn can manifest as pulmonary overcirculation (excessive pulmonary blood flow) or cyanosis (restrictive pulmonary blood flow). In some patients with restricted blood flow, a PDA is critical for survival. Systemic blood flow is derived directly from the LV.

●In patients with type II TV atresia with transposed great arteries, pulmonary blood flow is derived directly from the LV and systemic blood flow from the RV. In these patients, a VSD is critical as the RV, which provides the systemic circulation through the aorta, is dependent on blood flowing from the LV through the VSD. The presence of a restrictive or closing VSD and/or RV infundibular narrowing results in obstruction of systemic blood flow. If the obstruction is critical (severe), this results in diminished systemic circulation, leading to hypotension and, possibly, cardiogenic shock. In these patients, a PDA is critical for survival.

CLINICAL PRESENTATION

Fetal presentation — Advances in ultrasound technology have enabled antenatal screening between 18 and 22 weeks gestation to accurately make the diagnosis of TV atresia (image 1) [17]. TV atresia is compatible with fetal survival, but there are significant changes in fetal heart circulation. In the normal fetal heart, the right ventricle (RV) is the dominant ventricle, with distribution of approximately 65 percent of the combined cardiac output, whereas the left ventricle (LV) distributes 35 percent of the output, which has entered the left atrium through the foramen ovale (figure 2). The blood flow in the patent ductus arteriosus (PDA) is normally right-to-left from the RV to the descending aorta. In contrast, in fetuses with TV atresia, the LV assumes a dominant role as all of the systemic venous return crosses the foramen ovale from the right atrium to left atrium and, subsequently, the LV (figure 3). The presence of reverse (left-to-right flow) blood flow in the PDA suggests inadequate pulmonary outflow, which in turn indicates the need for postnatal initiation of prostaglandin therapy to maintain ductal patency required for adequate pulmonary blood flow and for survival. (See 'Initial medical management' below.)

In two case series of prenatally diagnosed TV atresia, approximately 4 percent of cases resulted in intrauterine death [16,18]. In both cohorts, the cause of death could not be ascertained, but a restrictive atrial level communication resulting in fetal hydrops was suggested as a cause for intrauterine demise [19]. There was also a significant rate of elective termination including 25 of 88 pregnancies in one study (28 percent) and 17 of 54 in the other (32 percent).

In one of the above studies, extracardiac anomalies were observed in 12 of the 54 cases: five with chromosomal anomalies; two with VACTERL association; and one fetus each with unilateral renal agenesis, hypospadias, hydrothorax, megacystis, and agenesis of the ductus venosus [18]. In addition, other case reports have observed increased nuchal thickness with normal karyotype in fetuses with TV atresia [17,20].

Postnatal presentation — Approximately 50 percent of patients who present postnatally with TV atresia do so on the first day of life, while an additional 30 percent present by one month of age [2]. The typical presenting symptoms are cyanosis and a heart murmur [2].

The clinical course and manifestations vary depending on the presence of other associated cardiac lesions (table 1). (See 'Classification' above.)

●Pulmonary atresia – In patients with tricuspid and pulmonary valve atresia (types Ia and IIa), pulmonary blood flow is derived exclusively from a PDA. As the PDA closes in response to increasing arterial oxygen levels, these infants develop hypoxemia and acidosis. Closure of the PDA can be prevented with the initiation of prostaglandin therapy. (See 'Initial medical management' below.)

●Ventricular septal defect (VSD) and normally related great arteries – In patients with normal anatomy of the great arteries and VSD (types Ib and Ic), the following spectrum of clinical manifestations are observed:

•In the absence of restricted pulmonary blood flow with a large VSD and no pulmonary stenosis, pulmonary blood flow increases in the first few weeks of life as the pulmonary vascular resistance drops. Symptoms of pulmonary overcirculation and heart failure are seen within two to three weeks after birth [4]. (See "Heart failure in children: Etiology, clinical manifestations, and diagnosis", section on 'Clinical manifestations'.)

•Patients with a small VSD or severe pulmonary stenosis will have a clinical course similar to those with pulmonary atresia. Patients with inadequate pulmonary blood flow will need initial management with prostaglandin infusion to maintain patency of a PDA to ensure adequate pulmonary blood flow.

•Because patients with TV atresia generally have a muscular VSD and the natural history of muscular VSD is to decrease in size over time, these patients may have episodes of hypoxic spells with increasing restriction of pulmonary blood flow as there is a decrease in the left-to-right shunting of blood through the shrinking VSD.

●Transposition of the great vessels – In patients with D-transposition of the great arteries (type II), the aorta arises from the hypoplastic RV. Since there is mixing of systemic and pulmonary circulations through an atrial level communication, postnatal circulation is similar to fetal circulation. As a result, patients present with cyanosis or decreased oxygen saturation. These patients may develop symptoms of pulmonary overcirculation (eg, tachypnea, increased work of breathing). However, in patients with aortic arch hypoplasia, coarctation may develop as the PDA closes because of constriction of ductal tissue in the affected region of the aorta. As a result, maintenance of ductal patency may be required to preserve flow into the aorta.

Physical examination — Central cyanosis is generally the most notable feature on physical examination. In addition, other findings include the following:

●On auscultation, a single second heart sound (S2) is heard. A holosystolic murmur may be heard at the left, lower sternal border when a VSD is present (movie 1). A continuous murmur may be evident in the setting of pulmonary atresia with a PDA (movie 2). (See "Approach to the infant or child with a cardiac murmur", section on 'Auscultation of heart sounds and murmurs'.)

●In patients with a restrictive atrial level communication, jugular venous distension with a prominent "a" wave and hepatomegaly may be detected.

●In patients with unrestrictive pulmonary blood flow, tachypnea may be present. In those with significant pulmonary blood flow, a diastolic rumble may be appreciated at the apex due to excessive mitral valve flow. This finding often signifies imbalance in circulation with a disproportionately large amount of pulmonary blood flow.

●Femoral pulses may be diminished with coarctation of the aorta.

Initial tests — Most patients will undergo initial testing that includes pulse oximetry screening, chest radiography, and electrocardiography. However, the diagnosis is generally made by echocardiography.

Pulse oximetry — Pulse oximetry, or arterial blood gas sampling, reveals oxygen desaturation consistent with the physical findings of cyanosis. The systemic oxygen saturation depends on the amount of left-to-right shunt through a PDA or, in some cases, VSD. (See "Newborn screening for critical congenital heart disease using pulse oximetry".)

Chest radiography — In the frontal projection of the chest radiograph, the smooth convexity of the right heart border is not seen and the lower aspect of the right heart border does not extend beyond the spine (image 2) [21,22]. There is variability in the heart size and prominence of pulmonary vascular findings depending on pulmonary blood flow:

●In patients with normal or decreased pulmonary blood flow (no VSD or small restricted VSD), there is a paucity of pulmonary markings and the heart size is usually normal

●In patients with increased pulmonary blood flow (eg, large VSD), there is often cardiomegaly and prominence of pulmonary vascularity

Electrocardiogram — Surface electrocardiography demonstrates tall P waves, left axis deviation with a superior axis (>30°), LV hypertrophy, and diminished RV forces (waveform 1). In a cyanotic infant, the above findings can be pathognomonic for TV atresia [4,23]. In patients with excessive pulmonary blood flow, a normal axis or right-axis deviation can be seen [23].

Natural course — The natural course of this disease in the absence of surgical intervention is poor, with a reported mortality of approximately 75 percent and the majority of deaths occurring in early childhood [21].

DIAGNOSIS

Fetal diagnosis — Fetal echocardiography, in the typical four-chamber view, can accurately make a diagnosis of TV atresia between 18 and 22 weeks gestation by detecting the presence of a hypoplastic right ventricle (RV) and no patent TV (image 1) [16,17]. Additional evaluation by fetal echocardiography should include assessment of the ventricular septum, relationship of the great arteries, status of pulmonary outflow, direction of flow in the patent ductus arteriosus (PDA), patency of the atrial level communication, and assessment for presence of fetal hydrops. As noted above, the presence of reverse flow (left-to-right flow) in the ductus arteriosus suggests inadequate pulmonary outflow, which in turn indicates the need for postnatal initiation of prostaglandin infusion to maintain a PDA for adequate pulmonary blood flow and for survival. (See 'Initial medical management' below.)

Postnatal diagnosis

Echocardiography — The postnatal definitive diagnosis of TV atresia is generally made by echocardiography, which includes both anatomic and hemodynamic evaluation. The characteristic anatomic features of an absent TV, atrial septal defect, and RV hypoplasia are readily demonstrated by two-dimensional echocardiography (image 3).

Echocardiography should also assess the location and relationship of the great arteries, the presence and size of a ventricular septal defect (VSD) including the degree of left-to-right shunting, the presence of pulmonary outflow obstruction, and the atrial level communication to rule out restriction to systemic and pulmonary venous mixing. In the presence of D-transposition of the great arteries (type II), the aortic arch must be assessed by two-dimensional and color Doppler imaging to determine whether there is coarctation of the aorta.

Other imaging tests — Other imaging modalities are rarely used to make the diagnosis of TV atresia:

●Cardiac catheterization has largely been replaced by echocardiography to make the diagnosis of TV atresia. It may be useful in delineating the anatomy in more complex lesions (eg, type III (table 1)). In addition, hemodynamic and angiographic assessment with cardiac catheterization provides useful information prior to palliative interventions.

●Cardiac magnetic resonance imaging and computed tomography scan can be helpful for evaluation in adults.

DIFFERENTIAL DIAGNOSIS — The differential diagnosis of most cases of TV atresia includes other cyanotic cardiac conditions that present with decreased pulmonary blood flow. (See "Cardiac causes of cyanosis in the newborn", section on 'Decreased pulmonary blood flow'.)

Echocardiography distinguishes TV atresia from these other cardiac lesions:

●Tetralogy of Fallot

●Tricuspid stenosis

●Pulmonary valve atresia

●Critical valvar pulmonary stenosis

In addition, echocardiography differentiates those cases of TV atresia with increased pulmonary blood flow due to a large ventricular septal defect (VSD) from other cardiac lesions with increased pulmonary blood flow. These conditions include D-transposition of the great arteries, truncus arteriosus, and totally anomalous pulmonary venous connection. (See "Cardiac causes of cyanosis in the newborn", section on 'Increased pulmonary blood flow'.)

MANAGEMENT

Overview — Neonates with TV atresia should be cared for at a tertiary medical center with experience in managing complex congenital heart disease. When an antenatal diagnosis is made, maternal transfer should be performed so that neonatal care can be given immediately after birth.

The management of TV atresia consists of the following:

●Initial medical management that ensures maintenance of adequate pulmonary blood flow and cardiovascular stability.

●Staged univentricular palliation. Cardiac transplantation, while an option, is not the preferred surgical approach owing, in part, to the scarcity of organs as well as the improved success with surgical palliation.

●If confounding factors preclude multiple surgical procedures (eg, multiple congenital anomalies or significant cerebrovascular accident), the family and care providers may choose compassionate care as a management approach for the infant.

Initial medical management — Initial management is focused on stabilization of cardiac and pulmonary function and ensuring adequate pulmonary blood flow through a patent ductus arteriosus (PDA). The goal of initial treatment is to stabilize and optimize the neonate's condition so that palliative repair can be performed.

Therapy consists of:

●Administration of prostaglandin E1 (alprostadil) to maintain adequate ductal dependent pulmonary blood flow. (See "Diagnosis and initial management of cyanotic heart disease in the newborn", section on 'Prostaglandin E1'.)

●General cardiorespiratory support for infants with respiratory compromise, hypotension, poor perfusion, acidosis, and hypothermia. These measures include respiratory support (eg, supplemental oxygen and/or mechanical ventilation), inotropic agents, and correction of acidosis and metabolic derangements (eg, hypoglycemia). (See "Diagnosis and initial management of cyanotic heart disease in the newborn", section on 'General supportive care'.)

Surgical management — The goal of staged single-ventricular palliation is to ensure adequate pulmonary and systemic blood flow with eventual separation of the two circulatory systems. As is true for most univentricular conditions (eg, hypoplastic left heart syndrome), the surgical management of TV atresia consists of three staged palliative procedures. (See "Hypoplastic left heart syndrome: Management and outcome", section on 'Surgical management'.)

The staged procedures are typically performed at the following ages:

●First stage is performed in neonates

●Second stage (bidirectional Glenn procedure) is usually performed at three to six months of age

●Third stage (eg, Fontan procedure) is usually performed at two to five years of age

In most institutions, including our own center, the Glenn and Fontan operations are performed as two stages to allow the body to adapt to the different hemodynamic states and reduce overall surgical morbidity and mortality. Others have advocated for a nonstaged approach to Fontan palliation [24]. Each approach carries its own set of advantages, but data are lacking on the superiority of one approach over the other.

First stage — The first stage of surgery is performed in the neonatal period. The goals of the initial palliation are to ensure that blood exiting the right atrium is unimpeded, provides adequate pulmonary blood flow, protects the pulmonary artery bed from high pressures that could result in higher risk for subsequent operations, and ensures unobstructed flow from the left ventricle (LV) to the aorta. The choice of initial palliative intervention depends on the anatomic variant (table 1). Outcomes in the various subtypes are generally comparable [25]. The general approach is as follows:

●Type I TV atresia (with normally related great arteries):

•Diminished pulmonary blood flow (types Ia and Ib) – With diminished pulmonary blood flow, the initial intervention soon after birth aims to restore a reliable source of pulmonary blood flow. This can be achieved through placement of a stent in the ductus arteriosus or with a modified Blalock-Thomas-Taussig shunt (also commonly called the modified Blalock-Taussig shunt [mBTS]). The mBTS uses a synthetic graft (typically a 3.5-mm Gore-Tex tube) to connect the innominate artery to the pulmonary artery (figure 4).

•Unobstructed pulmonary blood flow (type Ic) – If pulmonary blood flow is unobstructed, a pulmonary artery band may be placed in early infancy to restrict the amount of pulmonary blood flow and protect the pulmonary bed from high systemic pressures. Some infants who have unobstructed pulmonary flow through a ventricular septal defect (VSD) at birth may not require pulmonary artery banding, since the vast majority of VSDs decrease in size over time and restrict pulmonary blood flow. Pulmonary artery banding is generally restricted to patients who are symptomatic despite maximal medical therapy for pulmonary congestion/heart failure. Furthermore, a pulmonary artery band may stimulate ventricular hypertrophy that may more rapidly reduce the size of the VSD.

•Balanced circulation – Rarely, the degree of restriction to pulmonary blood flow is enough to maintain adequate oxygenation without pulmonary overcirculation and heart failure. These patients may not require surgery in the neonatal period and can be taken directly to the second stage of palliation.

●Type II TV atresia (with transposition of great arteries):

•Subaortic obstruction with a restrictive VSD – If there is significant subaortic obstruction with a restrictive VSD, the initial surgery consists of enlargement of the VSD or a Damus-Kaye-Stansel anastomosis (anastomosis between the main pulmonary artery and ascending aorta) with an mBTS.

•Isolated coarctation – If there is an isolated coarctation, it should be relieved and a pulmonary artery band may be considered to restrict pulmonary blood flow.

•Nonrestrictive VSD – Similar to type I lesions, in a few cases, the size of the VSD may be large enough to maintain systemic output, in which case, a pulmonary artery band alone may be adequate.

Interstage management — After the initial stage of palliation, the infant should be followed with close cardiac monitoring for signs of progressive cyanosis or congestive heart failure if necessary. Prior to stage II and stage III, a comprehensive evaluation including echocardiography and cardiac catheterization is undertaken to evaluate for hemodynamic and anatomic suitability. Interventions to address any residual anatomic lesions such as branch pulmonary artery stenosis, aortic coarctation, and coiling aortopulmonary collaterals can be undertaken during these catheterizations. Interstage management is discussed in greater detail separately. (See "Hypoplastic left heart syndrome: Management and outcome", section on 'Post-stage I management'.)

Second stage — The second palliative procedure for both type I and type II lesions is a cavopulmonary anastomosis (bidirectional Glenn procedure). This stage of palliation is typically performed at three to six months of life when infants experience progressive cyanosis as they begin to outgrow their neonatal shunt. This surgery involves removal of the original shunt and direct anastomosis of the superior vena cava to the right pulmonary artery. The Glenn procedure relies on passive venous drainage from the superior vena cava directly into the pulmonary artery. However, there is persistent systemic desaturation due to continued inferior vena cava flow into the right atrium. Surgical mortality following a traditional bidirectional Glenn procedure is low (between 1 and 2 percent). Outcomes following the bidirectional Glenn procedure in patients with single-ventricle physiology are discussed in greater detail separately. (See "Hypoplastic left heart syndrome: Management and outcome", section on 'Stage II: Cavopulmonary shunt'.)

Third stage — The third stage (the Fontan procedure) creates a venous pathway (total cavopulmonary connection) that directs the inferior vena caval flow into the pulmonary arteries, resulting in the entire systemic venous return flowing passively into the pulmonary arteries (figure 5). This creates a system with a single ventricle pumping blood into separate, in-series systemic and pulmonary circulations, thereby relieving cyanosis.

Several variants of the Fontan procedure have been used in the final stage of palliation for TV atresia (figure 5). In the classic atriopulmonary Fontan connection, the right atrium is directly anastomosed to the pulmonary arteries [26,27]. Subsequent modifications include the use of a lateral tunnel or an extracardiac conduit [28]. As a result of the Fontan procedure, the blood returning to the common (left) atrium is fully oxygenated and the single LV serves as the systemic pump (in contrast to hypoplastic left heart syndrome, in which the right ventricle [RV] is the systemic ventricle). Timing of surgery is variable but is usually at two to five years of age when there is progressive cyanosis due to increased physical activity. (See "Hypoplastic left heart syndrome: Management and outcome", section on 'Stage III: Fontan procedure'.)

Long-term complications associated with the classic right atrium to pulmonary artery anastomosis include right atrial enlargement, refractory atrial arrhythmias, poor exercise capacity, failing ventricular function, and protein-losing enteropathy [29]. As a result, Fontan revision with total cavopulmonary anastomosis with atrial reduction and surgical ablation of atrial tachycardia circuits have been undertaken with the goal of improving survival and exercise tolerance and reducing the need for antiarrhythmic agents [29-31], but the optimal timing for such conversion is unclear. Among long-term survivors of the Fontan operation, 65 percent of patients require either catheter-based or surgical reintervention by 20 years [32]. Outcomes following the Fontan procedure in patients with single-ventricle physiology are discussed in greater detail separately. (See "Hypoplastic left heart syndrome: Management and outcome", section on 'Stage III: Fontan procedure' and "Management of complications in patients with Fontan circulation".)

OUTCOME

Survival — Better patient selection, improved surgical techniques, and advances in perioperative care have contributed to lowering perioperative mortality in patients undergoing staged palliative repair. Interstage mortality continues to be an important contributor to reduced life expectancy in these patients [25]. In the contemporary era, approximately 90 percent of patients with TV atresia survive to the age of one year; 10-year survival is approximately 80 percent [11,24,25]. Risk factors for mortality include pulmonary atresia, underlying genetic syndromes, and the presence of extracardiac anomalies [25].

Morbidity — Long-term complications in patients who have undergone Fontan operation are discussed in detail separately. (See "Management of complications in patients with Fontan circulation".)

LONG-TERM MANAGEMENT — Long-term management of patients with TV atresia is similar to patients who have undergone Fontan operation for hypoplastic left heart syndrome and other single-ventricle variants. These issues are discussed in detail separately:

●Follow-up evaluations. (See "Overview of the management and prognosis of patients with Fontan circulation", section on 'Follow-up recommendations'.)

●Vaccination – Patients with TV atresia should receive all routine childhood vaccinations, including pneumococcal vaccine, yearly influenza vaccine, COVID-19 vaccine, and respiratory syncytial virus (RSV) immunoprophylaxis for eligible infants. Vaccinations are usually administered six weeks after major cardiac procedures or surgery. (See "Standard immunizations for children and adolescents: Overview" and "Pneumococcal vaccination in children" and "Seasonal influenza in children: Prevention with vaccines" and "COVID-19: Vaccines", section on 'Children' and "Respiratory syncytial virus infection: Prevention in infants and children".)

●Exercise. (See "Physical activity and exercise in patients with congenital heart disease" and "Overview of the management and prognosis of patients with Fontan circulation", section on 'Exercise'.)

●Endocarditis prophylaxis. (See "Prevention of endocarditis: Antibiotic prophylaxis and other measures".)

●Management of noncardiac surgery. (See "Anesthesia for adults with congenital heart disease undergoing noncardiac surgery".)

●Pregnancy. (See "Overview of the management and prognosis of patients with Fontan circulation", section on 'Reproductive issues'.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Congenital heart disease in infants and children".)

SUMMARY AND RECOMMENDATIONS

●Anatomy and pathophysiology – Tricuspid valve (TV) atresia is characterized by congenital agenesis or absence of the TV with no direct communication between the right atrium and ventricle. There is a spectrum of anatomic variants based on the morphology of the atresia and the presence of other cardiac structural lesions (eg, ventricular septal defect [VSD] and abnormal anatomy of the great arteries). (See 'Anatomy' above.)

Anatomic classification for TV atresia is based upon (table 1) (see 'Classification' above):

•Anatomy of the great arteries (which guides surgical management)

•Presence and size of a VSD

•Pulmonary blood flow

In all forms of TV atresia, the only exit of blood from the right atrium is through an interatrial communication. This obligate right-to-left atrial shunting is necessary for survival. In some patients, ductal patency may be required to maintain adequate pulmonary blood flow. (See 'Pathophysiology' above.)

●Prevalence – TV atresia is the third most common cyanotic heart condition, with an estimated prevalence of 0.5 to 1.2 per 10,000 live births. (See 'Epidemiology' above.)

●Clinical presentation – Patients can present prenatally as routine antenatal screening with echocardiography can accurately make the diagnosis of TV atresia in fetuses (image 1). Postnatally, patients present as neonates with cyanosis and a heart murmur. Other clinical features and course are dependent on the presence of associated cardiac lesions. (See 'Clinical presentation' above.)

●Initial tests – Initial tests may include (see 'Initial tests' above):

•Pulse oximetry screening or arterial blood gas sampling that demonstrates oxygen desaturation (see "Newborn screening for critical congenital heart disease using pulse oximetry")

•Chest radiograph showing loss of the smooth convexity of the right heart border (image 2) (see 'Chest radiography' above)

•Electrocardiogram demonstrating right atrial enlargement (tall P waves), superior axis (>30°), left ventricular hypertrophy, and diminished right ventricular forces (waveform 1) (see 'Electrocardiogram' above)

●Diagnosis – The definitive diagnosis of TV atresia is generally made by echocardiography with the detection of the characteristic anatomic features of an absent TV, atrial septal defect, and right ventricle (RV) hypoplasia (image 1 and image 3). (See 'Diagnosis' above.)

●Management – Neonates with TV atresia should be managed at a center with experience in managing complex congenital heart disease. When an antenatal diagnosis is made, delivery should be planned at a facility with a level III neonatal intensive care unit and pediatric cardiology expertise. If this is not feasible, transport arrangements should be established in advance of delivery. (See 'Management' above.)

•Initial stabilization – Initial stabilization includes general cardiorespiratory support and administration of prostaglandin E1 (alprostadil) to maintain patency of the ductus arteriosus in infants who have a ductal-dependent lesion. (See "Diagnosis and initial management of cyanotic heart disease in the newborn", section on 'Initial management'.)

•Surgical management – Surgical management of TV atresia consists of three staged palliative procedures. The third stage is a modified Fontan procedure that separates completely the pulmonary and systemic circulation, while maintaining adequate blood flow in each (figure 5). (See 'Surgical management' above.)

●Long-term follow-up – Long-term follow-up includes ongoing monitoring of cardiac function and exercise tolerance, endocarditis prophylaxis, and routine childhood vaccinations. (See 'Long-term management' above and "Overview of the management and prognosis of patients with Fontan circulation" and "Management of complications in patients with Fontan circulation".)

●Outcome – Survival has improved with advances in surgical and medical management. In the contemporary era, 10-year survival is approximately 80 percent. Long-term morbidity includes ventricular dysfunction, arrhythmia, risk of thrombosis, and complications related to lymphatic dysfunction. (See 'Outcome' above and "Overview of the management and prognosis of patients with Fontan circulation", section on 'Prognosis after Fontan procedure'.)

The natural course of TV atresia in the absence of surgical intervention is poor, with a reported mortality of approximately 75 percent, primarily occurring in early childhood. (See 'Natural course' above.)