Tricuspid Atresia 

Updated: Sep 25, 2016
Author: Mary C Mancini, MD, PhD, MMM; Chief Editor: Richard A Lange, MD, MBA 

Overview

Background

Tricuspid atresia is the third most common form of cyanotic congenital heart disease, with a prevalence of 0.3-3.7% in patients with congenital heart disease. The deformity consists of a complete lack of formation of the tricuspid valve with absence of direct connection between the right atrium and right ventricle.

Pathophysiology

Three types of tricuspid atresia are described, depending on the associated relationship of the great vessels. In type I, the great arteries are related normally; in type II, the great arteries are d-transposed; and in type III, the great arteries are l-transposed. The types are further subclassified according to the presence or absence of ventricular septal defects and pulmonary valve pathology.[1, 2]

Other cardiovascular anomalies occur in 15-20% of patients with tricuspid atresia. Most of the associated anomalies relate to transposition of the great vessels. A persistent left superior vena cava anomaly is observed in 15% of patients.

With the absence of the tricuspid valve and no continuity between the right atrium and right ventricle, venous blood returning to the right atrium can exit only by an intra-atrial communication. Because of the obligatory right-to-left shunt at the level of the atria, saturation of the left atrial blood is diminished.

The intracardiac blood flow in tricuspid atresia further depends on the presence or absence of pulmonary arterial pathology.[3] In the absence of pulmonary atresia or pulmonary valve stenosis, the volume of blood to the lungs may be normal with normal oxygenation occurring, resulting in reduced cyanosis. In contrast, with accompanying pulmonary artery or valve stenosis, pulmonary blood flow is reduced, resulting in increased cyanosis.

Pulmonary obstruction occurs most often in patients with tricuspid atresia and normally related great arteries. Patients with d-transposed great arteries and tricuspid atresia generally have unobstructed pulmonary blood flow.

The left ventricle comprises most of the ventricular mass in tricuspid atresia. Because of volume overload (the left ventricle receives all the venous return) and persistent hypoxemia, decreased ventricular function may result in fibrosis, decreased ejection fraction, mitral annular dilatation, and mitral insufficiency.

Epidemiology

United States data

The frequency of tricuspid atresia is 2.9% in autopsy series.

Race-, sex-, and age-related demographics

No racial predilection is apparent.

Considering all forms of tricuspid atresia, no sexual predilection exists. Males present more frequently with transposed great vessels than females.

The anomaly is congenital and is evident at birth.

Prognosis

Mortality/Morbidity

Depending on the degree of obstruction and associated anomalies, tricuspid atresia may be lethal at birth. Without repair, the patient rarely survives to adulthood.

 

Presentation

History

Tricuspid atresia is usually detected in infancy because of presenting cyanosis, congestive heart failure, and growth retardation. Parents provide a history of poor skin coloration (ranging from pallor to frank cyanosis), inability to complete a feeding session, frequent pauses during feeding, and/or frank anorexia. As a result, the infant demonstrates poor growth patterns. Respiratory difficulties are often reported as nasal flaring or muscle retractions. (See Medscape Reference article Pediatric Tricuspid Atresia.)

Bacterial endocarditis and brain abscess are common findings in patients with tricuspid atresia and should be considered in children with headaches, seizures, or neurologic deficits.

Physical

On inspection, cyanosis is the most common clinical feature of this lesion. The degree of cyanosis depends on the degree of pulmonary blood flow. Infants with associated diminished pulmonary blood flow or infants who depend on a patent ductus arteriosus manifest pronounced cyanosis that worsens as the ductus begins to close. Patients with relatively normal or increased pulmonary blood flow manifest little cyanosis but more pronounced congestive heart failure. For related information, see Medscape's Heart Failure Resource Center.

Digital clubbing is common in infants older than 3 months. Jugular venous pulsations and distention are common.

The peripheral pulses and pulse volume may be decreased, normal, or increased. The left ventricular impulse is prominent because of volume overload. The apical impulse is hyperdynamic, with displacement to the left of the midclavicular line. A thrill may be felt at the left sternal border in patients with a restrictive ventricular septal defect or pulmonary valve stenosis. The liver may be large and pulsatile.

A single first heart sound that may be increased in intensity is usually present. The second heart sound may be single or normally split. The intensity of this sound varies, depending on associated transposition of the great vessels. In normally related great vessels, the second heart sound may be of normal intensity. In transposed great vessels, the second sound is diminished. Cardiac murmurs are present in 80% of patients with tricuspid atresia. A holosystolic murmur that may have a crescendo and decrescendo quality is present, signifying blood flow through the ventricular septal defect. A continuous murmur may be present. Systemic-to-pulmonary arterial collaterals or arterial-to-pulmonary arterial anastomoses surgically created to improve pulmonary blood flow may cause this finding. A murmur of mitral insufficiency may also be present.

Causes

The cause is unknown. Although specific genetic causes of the malformation remain to be determined in humans, the FOG2 gene may be involved in the process. Mice in which the FOG2 gene is knocked out are born with tricuspid atresia. The significance of this finding and its applicability in humans requires further investigation.

 

DDx

 

Workup

Laboratory Studies

The following laboratory studies may be useful:

  • CBC count: Because of cyanosis in this population, polycythemia may be present.

  • Prothrombin time and activated partial thromboplastin time: Findings from these studies may be abnormal secondary to the polycythemia.

Imaging Studies

Chest radiography

Cardiomegaly is usually present, with a prominent right heart border that reflects enlargement of the right atrium.

In 80% of patients, pulmonary vascular markings are diminished because of diminished pulmonary blood flow. Pulmonary vascular markings may be increased when pulmonary flow is not obstructed.

A right aortic arch may be observed in 3-8% of cases.

Tricuspid atresia. Frontal chest radiograph in a c Tricuspid atresia. Frontal chest radiograph in a child with tricuspid atresia and a nonrestrictive ventricular septal defect. There is pulmonary plethora. Note the prominent right atrium.
Tricuspid atresia. Frontal chest radiograph in a c Tricuspid atresia. Frontal chest radiograph in a child with tricuspid atresia and a nonrestrictive ventricular septal defect, mild pulmonary plethora and, atypically, a right aortic arch (arrow). Note enlarged right atrium and the typical rounded configuration of the left cardiac apex. In the absence of the right ventricle, the left ventricle becomes hypertrophied and dilated, causing the development of a more rounded cardiac apex.
Tricuspid atresia. Frontal chest radiograph in an Tricuspid atresia. Frontal chest radiograph in an adult with untreated tricuspid atresia. Increased pulmonary blood flow through a nonrestrictive ventricular septal defect has been tolerated for years but has led to the development of pulmonary hypertension, as shown by the large proximal pulmonary arteries (arrows) and pruned distal pulmonary arteries. The development of pulmonary hypertension prevents conventional surgical treatment.

Echocardiography

The diagnosis of tricuspid atresia can be reliably established with this noninvasive method.

The basic anatomy, size of the atrial septal defect, relationship of the great vessels, degree of pulmonary blood flow, ventricular function, and valvular function can be easily ascertained using a combination of M-mode, 2-dimensional, and color-flow echocardiography.[4]

Other Tests

Electrocardiography

Sinus rhythm is generally present, with tall P waves indicative of atrial enlargement.

First-degree atrioventricular block may be observed.

Because of the origin of the left bundle branch from a common bundle, the frontal plane QRS axis may be leftward or superior.

Procedures

Cardiac catheterization

In infants, the primary use of cardiac catheterization is to determine the source and reliability of pulmonary blood flow and, in particular, to assess the status of the patent ductus arteriosus. If a restrictive atrial septal defect is present, then balloon septostomy can be performed in this setting.

In the older population, arteriography is used to define details important in surgical management such as number and relationship of vena cavae, size of the pulmonary arteries, pulmonary artery resistance, mitral valve competency, and definition of prior operative procedures.

 

Treatment

Medical Care

The following 3 considerations guide the treatment of infants with tricuspid atresia:

  • The amount of pulmonary blood flow must be regulated in order to decrease hypoxemia or symptoms of congestive heart failure.

  • Myocardial function, the integrity of the pulmonary vascular bed, and pulmonary vascular integrity must be preserved in order to optimize conditions for a later Fontan operation.

  • The risk of bacterial endocarditis and thromboembolism must be minimized.

Routinely initiate prophylaxis against bacterial endocarditis when any invasive or dental procedure is contemplated.

  • Infants with decreased pulmonary blood flow

    • This cohort encompasses most of the infants with tricuspid atresia.

    • Marked cyanosis and hypoxemia characterize the clinical course. Acidemia may occur if the hypoxemia is profound, and death can ensue.

    • Promptly treat infants with severe hypoxemia with prostaglandin E infusions in order to maintain patency of the ductus arteriosus and improve pulmonary blood flow.

  • Infants with increased pulmonary blood flow

    • These infants have an associated unrestrictive ventricular septal defect and transposed great vessels.

    • They present with severe congestive heart failure and benefit from digitalis and diuretic therapy until an operative intervention can be undertaken to restrict the pulmonary blood flow.

  • Palliative procedures

    • The intelligent application of palliative procedures to control the amount of pulmonary blood flow in this lesion improves the survival of infants with tricuspid atresia. With standard palliative procedures, 50% of these infants can survive into their teen years.

    • Nonetheless, these children are at risk for developing complications of the disease, including paradoxical emboli, stroke, brain abscess, polycythemia, progressive cardiac dilatation, ventricular dysfunction, mitral valve insufficiency, and arrhythmias.

Surgical Care

Most patients with tricuspid atresia require some form of surgical treatment during the first year of life. Cyanosis with decreased pulmonary blood flow is the most common indication for surgical intervention. In this instance, a shunt procedure is undertaken to connect the systemic circulation to the pulmonary circulation. The shunt can be from the subclavian artery to the pulmonary artery (Blalock-Taussig shunt) or a cavopulmonary anastomosis (Glenn shunt). In patients with severe congestive heart failure indicative of increased pulmonary blood flow, pulmonary artery banding may be required to decrease the blood flow to the lungs and to assist with treatment of the accompanying congestive heart failure.[5, 6]

In an investigation of the association between surgical management of pulmonary blood flow at initial and staged procedures with survival to Fontan/Kreutzer operation in patients with tricuspid atresia, Wilder et al studied 302 infants with tricuspid atresia type I. They used multiphase parametric-hazard models to analyze competing outcomes among patients who underwent systemic to pulmonary artery shunt (SPS), pulmonary artery banding (PAB), or superior cavopulmonary connection (SCPC). Based upon the results, the investigators conclude that tricuspid atresia patients with SPS are a high-risk subgroup and that avoiding open ductus arteriosus and concomitant main pulmonary artery (MPA) intervention during SPS may help to mitigate the risk associated with SPS.[7]

In a study of the influence of morphology and initial surgical palliation strategy on the survival of infants with tricuspid atresia, Alsoufi et al found that multistage palliation outcomes of various tricuspid atresia subtypes are comparable and generally good, except for patients who have associated genetic/extracardiac anomalies. They found that the bulk of patient mortality is interstage. This emphasizes the ongoing need for improved monitoring and patient management during this period.[8]

Recurrence of the cyanosis, progressive polycythemia, decreasing exercise tolerance, shunt failure, or increasing pulmonary obstruction are indications for re-evaluation and consideration of a second operative procedure. A Fontan procedure is undertaken if the criteria are met; otherwise, a second palliative procedure should be performed.

The Fontan operation excludes the right ventricle through the formation of a right atrial-to-pulmonary artery connection or an extracardiac cavopulmonary anastomosis using a synthetic graft. Several parameters should be met to ensure a successful outcome.[9]  Note the following:

  • The candidate should be aged 4 years or older.

  • A right atrium of normal volume and normal caval drainage should be present.

  • Sinus rhythm should be present.

  • Mean pulmonary artery pressure should be low (ie, < 15 mm Hg), as should mean pulmonary arteriolar resistance.

  • The pulmonary artery-to-aorta diameter ratio should be greater than 0.75.

  • Previous shunt procedures should not exert impairing effects.

    Fontan procedure: Illustration of the atrial-to-pu Fontan procedure: Illustration of the atrial-to-pulmonary artery anastomosis.
  • In a subset of patients with a single functional ventricle and cardiac abnormalities, including tricuspid atresia, pulmonary atresia with intact ventricular septum, and double outlet right ventricle, a 3-stage Fontan pathway without cardiopulmonary bypass may be achievable and safe.[10]

  • The operative procedure connects the right atrium to the systemic pulmonary artery system at the outflow tract or at the bifurcation of the main trunk. Any atrial septal defect is closed.[11, 12, 13, 14, 15, 16, 17, 18]

Consultations

The treatment of these children must be coordinated with a pediatric cardiac surgeon, pediatric cardiologist, neonatologist, and pediatric pulmonologist/intensivist.

Diet

Because of the volume overload present in these children and the use of diuretics, a low-sodium diet should be prescribed. Be attentive to replacement of appropriate electrolytes and the maintenance of nutrition to foster proper growth and development.

Activity

Encourage activity in these children, who often limit activities secondary to the presence of dyspnea from congestive heart failure.

 

Medication

Medication Summary

Digitalis and diuretics are used to control the congestive heart failure present in patients with tricuspid atresia.

Antiarrhythmics, inotropic agents

Class Summary

Improve ventricular contractility and maintain normal sinus rhythm.

Digoxin (Lanoxin, Lanoxicaps)

Cardiac glycoside with direct inotropic effects in addition to indirect effects on the cardiovascular system. Acts directly on cardiac muscle, increasing myocardial systolic contractions. Indirect actions result in increased carotid sinus nerve activity and enhanced sympathetic withdrawal for any increase in mean arterial pressure.

Diuretics

Class Summary

Decrease circulating pulmonary blood volume.

Furosemide (Lasix)

Increases excretion of water by interfering with chloride-binding cotransport system, which in turn inhibits sodium and chloride reabsorption in ascending loop of Henle and distal renal tubule.

Individualize dose to patient. Depending on response, administer at increments of 20-40 mg, no sooner than 6-8 h after previous dose, until desired diuresis occurs. When treating infants, titrate with 1-mg/kg/dose increments until a satisfactory effect is achieved.

 

Follow-up

Further Outpatient Care

For patients who have undergone a palliative procedure, arrange careful follow-up to monitor pulmonary blood flow. Increasing polycythemia and cyanosis are indicative of poor shunt flow and may indicate that another procedure is needed to prevent worsening hypoxemia.

Increased pulmonary blood flow is detrimental in this population; monitor carefully, watching for signs of congestive heart failure.

For patients who have had the Fontan procedure, maintain follow-up care to ensure a stable cardiac rhythm. Consider careful assessment of ventricular function on a routine basis. These patients may develop signs of congestive heart failure and congestive hepatopathy in the early postoperative course. In such instances, institute diuretic therapy early in order to preserve pulmonary blood flow and oxygenation.

Further Inpatient Care

Because pulmonary blood flow is of paramount importance in patients with tricuspid atresia, carefully monitor for signs of hypoxemia or fluid overload. After a palliative procedure, perform echocardiographic assessments to determine the patency of the shunt. Clinical evaluation is of benefit to determine instances of increased pulmonary blood flow that require treatment for ensuing congestive heart failure. Signs of hypoxemia in the form of rising hemoglobin levels must be monitored carefully because onset is insidious.

Inpatient care after the Fontan procedure requires careful monitoring of pulmonary vascular resistance, heart rhythm, and fluid status. All efforts are made to maintain pulmonary vascular resistance as low as possible using supplemental oxygen and pulmonary vasodilators. Maintaining normal sinus rhythm in these patients optimizes cardiac output and ensures a favorable outcome. These patients characteristically develop pleural effusions after the procedure, which must be monitored carefully and removed in order to maximize oxygenation and decrease pulmonary vascular resistance.

Carefully examine the child for signs of hepatic congestion. Hepatic congestion can occur secondary to the operative procedure and the subsequent volume overload. Treatment consists of diuretic therapy.

Inpatient & Outpatient Medications

Consider digitalis to maintain sinus rhythm and improve cardiac contractility.

Diuretics are often administered to treat and prevent pulmonary edema in these patients.

Complications

The complications from a shunt procedure can include too much pulmonary blood flow. The shunt can also cause damage to the pulmonary arteriolar tree.

Complications from the Fontan procedure include pulmonary edema, congestive hepatopathy, pleural effusions, ascites, protein-losing enteropathy, and cardiac arrhythmias.

Prognosis

The 1-year survival rate after the Fontan operation is 85%; the 5-year survival rate is 78%. Because the procedure eliminates cyanosis, polycythemia and left ventricular volume overload are relieved; therefore, this population can be expected to live longer.

Patient Education

Counsel the parents of these children about dietary sodium restriction, as well as the signs and symptoms of hypoxemia and congestive heart failure.