Tetralogy of Fallot (TOF) in Adults 

Updated: Nov 13, 2018
Author: Shabir Bhimji, MD, PhD; Chief Editor: Yasmine S Ali, MD, FACC, FACP, MSCI 

Overview

Practice Essentials

Tetralogy of Fallot (TOF) (pronounced te-tral-uh-jee of Fal-oh), one of the most common congenital heart disorders, comprises right ventricular (RV) outflow tract obstruction (RVOTO) (infundibular stenosis), ventricular septal defect (VSD), aorta dextroposition (overriding aorta), and RV hypertrophy (see the image below). The mortality rate in untreated patients reaches 50% by age 6 years, but in the present era of cardiac surgery, children with simple forms of tetralogy of Fallot enjoy good long-term survival with an excellent quality of life.

However, it is important to understand that corrective surgery for tetralogy of Fallot performed in childhood is not curative surgery. As a result, many children with repaired tetralogy of Fallot survive into adulthood and are seen at cardiology clinics.[1, 2]  Some patients who never underwent surgery for mild tetralogy during childhood may present as adults with a variety of symptoms, and other patients who may only have had a palliative procedure (eg, shunt placement) can also present as adults.[3]  

Anatomic findings in tetralogy of Fallot are depic Anatomic findings in tetralogy of Fallot are depicted.

Signs and symptoms of tetralogy of Fallot

The clinical features of tetralogy of Fallot in the adult are directly related to the severity of the anatomic defects and may include the following:

  • Lack of exercise endurance

  • Palpitations

  • Gradual decline in bodily functions

Infants, however, often display the following:

  • Difficulty with feeding

  • Failure to thrive

  • Episodes of bluish pale skin during crying or feeding (ie, "Tet" spells)

  • Exertional dyspnea, usually worsening with age

Physical findings in adults include the following:

  • Exertional dyspnea

  • Syncope

  • Palpitations

  • Evidence of right-sided heart failure (eg, elevated jugular venous pressure [JVP], ascites, peripheral edema, hepatomegaly)

  • Large "A wave" in JVP tracings

  • In individuals with pulmonary valve insufficiency: Low-pitched, short diastolic murmur; may have an extra heart sound (ejection click); may have a murmur

  • RV dysfunction, arrhythmias

See Presentation for more detail.

Diagnosis of tetralogy of Fallot

In adult patients, the following laboratory studies may be helpful:

  • Complete blood cell count: A mild anemia may be present; polycythemia is rare in the absence of cyanosis.

  • Coagulation profile: May be abnormal in patients with cyanosis and bleeding

  • Arterial blood gas (including serum lactate, base excess, oxygen partial pressure [PO2]): The patient's oxygenation status, serum lactate levels, and base excess value appear to be prognostic markers for mortality in those undergoing surgical repair of tetralogy of Fallot.[4]

  • Blood cultures: Obtain blood cultures in febrile patients to rule out endocarditis or sepsis.

Imaging studies include the following:

  • Chest radiographs

  • Echocardiography

  • Magnetic resonance imaging (MRI)

Chest radiographs have the following attributes:

  • May be normal or depict cardiomegaly and prominent RV shadowing

  • Although the classic boot-shaped heart (coeur en sabot) is the hallmark of the disorder in infants, this shape of the heart may not be seen in adult patients.

Echocardiography has the following attributes:

  • Color-flow Doppler echocardiography: Assesses overall cardiac function and the status of the valves, and for the presence of any residual VSD, ductus arterosus, or atrial septal defect

  • Allows evaluation of the valvular anatomy but is unable to visualize the coronary anatomy in adults

  • Reveals the grade and severity of any RVOT obstruction

MRI has the following attributes:

  • Gold standard for assessing RV function and size, and for quantifying the pulmonary regurgitant volume

  • Maps the velocity of pulmonary regurgitation and provides good delineation of the aorta size and assessment of the pulmonary arteries and its branches, the status of the RVOT, and the presence of VSDs, and/or RV hypertrophy[5]

  • Can also be used to measure intracardiac pressures, gradients, and blood flows

Cardiac catheterization is useful in any of the following settings:

  • When the anatomy cannot be completely defined by echocardiography

  • When disease in the pulmonary arteries is a concern

  • When pulmonary vascular hypertension is possible

Cardiac catheterization allows the following:

  • Assessment of the pulmonary annulus size and pulmonary arteries

  • Assessment of the severity of RVOTO

  • Location of the position and size of the VSD

  • Ruling out possible coronary artery anomalies

See Workup for more detail. See also the Guidelines section for the 2018 American Heart Association/American College of Cardiology (AHA/ACC) recommendations for the management of adults with tetralogy of Fallot. 

Treatment of tetralogy of Fallot

For adults with acute cyanosis, place them in a knee-chest position. In addition, provide/administer the following:

  • Oxygen

  • IV morphine

  • IV propranolol for severe cases[6]

Most symptomatic adults with tetralogy of Fallot require some type of surgical intervention. Pulmonary valve replacement is the most common procedure performed, usually under cardiopulmonary bypass.

Factors that increase the risk for surgery in adult patients with tetralogy of Fallot include the following:

  • Cardiogenic shock

  • Poor RV function

  • Diminutive pulmonary arteries

  • Other major associated anomalies, such as tricuspid atresia or an anomalous coronary artery

  • Multiple previous surgeries

  • Advanced age

  • Severe annular hypoplasia

  • High peak RV–to–left ventricular pressure ratio

  • Multiple ventricular septal defects (VSDs)

  • Right-sided heart failure

See Treatment and Medication for more detail, as well as the Guidelines section for the 2018 American Heart Association/American College of Cardiology (AHA/ACC) recommendations for the management of adults with tetralogy of Fallot.

Background

Tetralogy of Fallot (TOF) (pronounced te-tral-uh-jee of Fal-oh) is one of the most common congenital heart disorders (CHDs). This condition is classified as a cyanotic heart disorder, because tetralogy of Fallot results in an inadequate flow of blood to the lungs for oxygenation (right-to-left shunt) (see the following image). Patients with tetralogy of Fallot initially present with cyanosis shortly after birth, thereby attracting early medical attention. In most cases, the cyanosis does not present for a few weeks or months after birth; however, infants born with transposition of the great vessels usually present with cyanosis immediately after birth.

Anatomic findings in tetralogy of Fallot are depic Anatomic findings in tetralogy of Fallot are depicted.

Typical features

The four features typical of tetralogy of Fallot include right ventricular (RV) outflow tract obstruction (RVOTO) (infundibular stenosis), ventricular septal defect (VSD), aorta dextroposition (overriding aorta), and right ventricular hypertrophy. Occasionally, a few children also have an atrial septal defect (ASD), which makes up the pentad of Fallot. The basic pathology of tetralogy is due to the underdevelopment of the RV infundibulum, which results in an anterior-leftward malalignment of the infundibular septum. This malalignment determines the degree of RVOTO.

The clinical features of tetralogy of Fallot are generally typical, and a preliminary clinical diagnosis can almost always be made. Because most infants with this disorder require surgery, it is fortunate that the availability of cardiopulmonary bypass (CPB), cardioplegia, and surgical techniques is now well established. Most surgical series report excellent clinical results with low morbidity and mortality rates.

Surgery in infancy

The first surgery to repair tetralogy of Fallot consisted of placement of a shunt to relieve the cyanosis. Primary repair is currently recommended within the first 12 months of life; in general, excellent results are obtained at most centers. Ever since primary repair of tetralogy of Fallot became the standard of care nearly 30 years ago, more adult patients with repaired tetralogy of fallot in early childhood are living longer,[1, 2]  and they are being seen at many cardiac clinics. Some patients who never underwent surgery for mild tetralogy during childhood may present as adults with a variety of symptoms, and other patients who may only have had a palliative procedure (eg, shunt placement) can also present as adults.[3]

What happens years after surgical repair?

It is important to understand that corrective surgery for tetralogy of Fallot performed in childhood is not curative surgery. Rather, this procedure only corrects the anatomic defects—without changing the progression of the disease or addressing the consequences of using a patch. As a result, these individuals develop new symptoms and eventually present to the cardiology clinic with diverse symptoms. Thus, most pediatric surgeons consider the initial surgery for tetralogy of Fallot to be long-term palliation, not definitive surgery.

With advancing age, children with tetralogy of Fallot who had corrective surgery are usually asymptomatic for the first decade after the initial procedure. Thereafter, they develop adverse myocardial problems, the majority of which involve varying degrees of pulmonary valve insufficiency, which, in turn, can lead to RV overload and RV distention and failure.[7]

RV enlargement also leads to the development of atrial and ventricular arrhythmias, which, if not recognized early, are a common cause of high morbidity and mortality. An estimated one third of adults with tetralogy of Fallot experience atrial and ventricular arrhythmias over a period of 2-3 decades. The incidence of sudden death ranges from 5% to 7% in patients who develop these arrhythmias.{ref53-INVALID REFERENCE}

Another concern regarding patients with tetralogy of Fallot is that many are lost to follow-up as they become adults, and thus the opportunity to manage complications before they become irreversible can be missed. Several surveys indicate that many children with repaired tetralogy of Fallot feel fine after surgery, believe that they are cured, and then stop seeing their cardiologist. In other cases, the primary care provider is unaware of the need to follow these patients, owing to the erroneous belief that surgery is curative.

See also Tetralogy of Fallot With Pulmonary Stenosis, Tetralogy of Fallot With Pulmonary Atresia, and Tetralogy of Fallot With Absent Pulmonary Valve.

Historical information

Louis Arthur Fallot, after whom the name tetralogy of Fallot is derived, was not the first person to recognize the condition. Stensen first described it in 1672; however, it was Fallot who first accurately described the clinical and complete pathologic features of the defects.

Although the disorder was clinically diagnosed much earlier, no treatment was available until the 1940s. Cardiologist Helen Taussig recognized that cyanosis progressed and inevitably led to death in infants with tetralogy of Fallot. She postulated that the cyanosis was due to inadequate pulmonary blood flow. Her collaboration with Alfred Blalock led to the first type of palliation for these infants. In 1944, Blalock operated on an infant with tetralogy of Fallot and created the first Blalock-Taussig shunt between the subclavian artery and the pulmonary artery (see the image below).

This image shows completed blocking with a Taussig This image shows completed blocking with a Taussig shunt.

The pioneering Blalock-Taussig shunt surgical technique opened a new era in neonatal cardiac surgery. Development of the Potts shunt (from the descending aorta to the left pulmonary artery), the Glenn shunt (from the superior vena cava to the right pulmonary artery), and the Waterston shunt (from the ascending aorta to the right pulmonary artery) followed.

Scott performed the first open correction in 1954. Less than 6 months later, Lillehei performed the first successful open repair for tetralogy of Fallot using controlled cross-circulation, with another patient serving as oxygenator and blood reservoir. The following year, with the advent of cardiopulmonary bypass by Gibbons, another historic era of cardiac surgery was established. Since then, numerous advances in surgical technique and myocardial preservation have evolved in the treatment of tetralogy of Fallot.

Anatomy

The classic anatomic features of adult patients with tetralogy of Fallot (TOF) are no different from those seen in pediatric patients, such as the following[8] :

  • Perimembranous ventricular septal defect (VSD)
  • Right ventricular (RV) outflow tract obstruction (RVOTO)
  • An overriding aorta
  • RV hypertrophy
Anatomic findings in tetralogy of Fallot are depic Anatomic findings in tetralogy of Fallot are depicted.

Aorta

The aorta in patients with tetralogy of Fallot is hugely dilated and overrides the diminutive pulmonary artery.  In about 25% of cases, the aorta arises from a right-sided aortic arch. Because of this feature and overriding of the septum, about 50% of the blood flow from the aorta arises from the RV via the large perimembranous VSD.

RVOTO

In the majority of adults with tetralogy of Fallot,  there is resistance to RV emptying. The obstruction is caused by the anterior displacement and rotation of the infundibular septum which narrows the outflow tract. The infundibular obstruction may be associated with pulmonary valve stenosis or atresia, which results in further outflow tract obstruction.

Pulmonary arteries

The size of the pulmonary arteries in tetralogy of Fallot vary in size and distribution. In most cases, the vessels are hypoplastic but can be atretic in severe cases. An almost universally common feature of tetralogy of Fallot is reduced blood flow in the pulmonary arteries and, hence cyanosis. There are also reported cases of an absent left pulmonary artery. In close to three quarters of patients with TOF, there is pulmonary valve stenosis, which is often due to leaflet tethering rather than commissural fusion. In virtually all such cases, the pulmonary annulus is narrowed.

Associated anomalies

Associated heart defects are very common in tetralogy of Fallot. Some patients may have an atrial septal defect, often referred to as part of the pentad of Fallot. Other common defects include a patent ductus arteriosus, muscular VSD, atrioventricular septal defects, anomalous coronary arteries, anomalous pulmonary venous return, absent pulmonary valve, aortic incompetence, and aortopulmonary window.[9, 10]

Etiology and Pathophysiology

Pathophysiology in pediatric patients with tetralogy of Fallot

The cause(s) of most congenital heart diseases (CHDs) are unknown, although genetic studies suggest a multifactorial etiology. Methylene tetrahydrofolate reductase (MTHFR) gene polymorphism may be a susceptibility gene for tetralogy of Fallot (TOF).[11, 12]  More recently, it appears that VEGF genetic polymorphisms, -2578C>A and -634C>G, may be associated with an increased risk for tetralogy of Fallot, whereas the risk is potentially reduced with 936C>T polymorphism.[13]

Prenatal factors associated with a higher incidence of tetralogy of Fallot include maternal rubella (or other viral illnesses) during pregnancy, poor prenatal nutrition, maternal alcohol use, maternal age older than 40 years, maternal phenylketonuria (PKU) birth defects, and diabetes. Children with Down syndrome also have a higher incidence of tetralogy of Fallot, as do infants with fetal hydantoin syndrome or fetal carbamazepine syndrome.

In addition, as one of the conotruncal malformations, tetralogy of Fallot can be associated with a spectrum of lesions known as CATCH 22 (cardiac defects, abnormal facies, thymic hypoplasia, cleft palate, hypocalcemia). Cytogenetic analysis may demonstrate deletions of a segment of chromosome band 22q11 (DiGeorge critical region). Ablation of cells of the neural crest has been shown to reproduce conotruncal malformations.

These abnormalities are associated with the DiGeorge syndrome and branchial arch abnormalities.

The hemodynamics of tetralogy of Fallot depend on the degree of right ventricular (RV) outflow tract obstruction (RVOTO). The ventricular septal defect (VSD) is usually nonrestrictive, and the RV and left ventricular (LV) pressures are equalized. If the obstruction is severe, the intracardiac shunt is from right to left, and pulmonary blood flow may be markedly diminished. In this instance, blood flow may depend on the patent ductus arteriosus (PDA) or bronchial collaterals.

Pathophysiology in the adult with tetralogy of Fallot

Previously, clinicians often ordered routine echocardiograms in adult patients with tetralogy of Fallot who were followed in the clinic following surgery in infancy. At that time, it was felt that, as in cases of tricuspid regurgitation, pulmonary valve insufficiency was a relatively benign and inconsequential observed entity. Because most affected patients were not symptomatic, they were never treated. However, observation of these patients over time revealed that they began to develop severe RV dysfunction and arrhythmias. The RV dilatation from the pulmonary valve insufficiency is associated with fibrosis and severe myocardial damage, which then often lead to a decrease in exercise endurance, and the majority of patients soon develop ventricular arrhythmias.[14]

Initially most patients with chronic RV function are asymptomatic, but as the compensatory mechanisms fail and the ejection fraction decreases, symptoms start to appear. If the condition is not treated at this stage, the RV dysfunction is irreversible. The arrhythmias occur as a result of progressive dilatation and stretching of the right atrium and RV.

Arrhythmias

Atrial arrhythmias of clinical significance are chiefly of the reentry type, but they may also include atrial tachycardia and atrial fibrillation. These atrial arrhythmias occur in 10-35% of patients with repaired tetralogy of Fallot.[15]

Ventricular arrhythmias and sudden death are also known to occur in those with repaired tetralogy of Fallot. Case studies have revealed that patients who experience sudden death often have moderate to severe pulmonary valve insufficiency at the time of death. Ventricular arrhythmias tend to be less common in patients with mild pulmonary valve insufficiency.

Overall, the risk of late sudden death is many times greater in patients who survive tetralogy of Fallot surgery than in their age-matched counterparts.[16]

Epidemiology

Tetralogy of Fallot (TOF) represents approximately 7%-10% of congenital heart diseases (CHDs),[2] and it is the most common cyanotic CHD, with 0.23-0.63 cases per 1,000 births.[1] This disorder accounts for one third of all CHD in patients younger than 15 years; in adults, tetralogy of Fallot has an estimated prevalence of 1 in 3,500 to 1 in 4,300 people.[2]  

In most cases, tetralogy of Fallot is sporadic and nonfamilial. The incidence in siblings of affected parents is 1-5%, and it occurs more commonly in males than in females. The disorder is associated with extracardiac anomalies such as cleft lip and palate, hypospadias, and skeletal and craniofacial abnormalities. Genetic studies indicate that in some patients with tetralogy of Fallot, there may be 22q11.2 deletion and other submicroscopic copy number alterations.[17]

Adult patients with tetralogy of Fallot currently represent a very large group of patients who underwent congenital heart surgery in early life. Although the exact number of these adults is not known, because many are lost to follow-up or have never been followed, it is estimated that over two thirds of affected children who undergo repair of tetralogy of Fallot in early childhood will reach adulthood, with one study showing 94% survival rate of 168 patients aged 16 years and older who underwent simple repair.[16]  For individuals born with this condition, the 30-year survival is above 75%, provided these individuals have been clinically followed. Limited data to date reveal that adult tetralogy of Fallot is equally common in both sexes.

The majority of adult patients with repaired tetralogy of Fallot present after the second or third decade of life. Males and females appear to be equally affected with symptoms as they age.[18]

Prognosis

In the present era of cardiac surgery, children with simple forms of tetralogy of Fallot (TOF) enjoy good long-term survival with an excellent quality of life. Late outcome data suggest that most survivors are in New York Heart Association (NYHA) classification I, although maximal exercise capability is reduced in some.

About 75% infants who undergo repair during infancy will survive to reach their second to third decade of life without major consequences. However, after the first two decades of life, symptoms start to appear due to pulmonary valve regurgitation. By the fourth decade of life, most survivors are symptomatic.

Adult patients with tetralogy of Fallot who undergo surgery again are usually symptom free for 10-15 years, but by the time they reach their fifth decade, even these patients begin to have symptoms.[16] Although the second surgery reduces the rate of death, the majority of these individuals have a shorter lifespan than age-matched control subjects without a history of congenital heart disease. Adults with recalcitrant arrhythmias and right heart failure have the worst prognosis.

Sudden death from ventricular arrhythmias has been reported in 1-5% of patients at a later stage in life, and the cause remains unknown. It has been suspected that ventricular dysfunction may be the cause. One study found left ventricular longitudinal dysfunction to be associated with a greater risk of developing life-threatening arrhythmias.[19] Continued cardiac monitoring into adult life is necessary. For some time, it has been suspected that certain children may have inherited a predispostion to developing long QT syndrome. A 2012 study by Chiu confirmed this suspicion.[20]

Most individuals who survive to age 30 years develop congestive heart failure (CHF), although individuals whose shunts produce minimal hemodynamic compromise have been noted, albeit rarely, and these individuals achieve a normal life span. Survival of patients into their 80s have been reported. Due to advanced surgical techniques, a 40% reduction in deaths associated with tetralogy of Fallot was noted from 1979 to 2005.[18]

Complications

Adults with repaired tetralogy of Fallot during infancy can present with the following complications later in life:

  • Right heart failure

  • Atrial and ventricular arrhythmias

  • Sudden death

  • Endocarditis

  • Septic central emboli

See Surgical Complications in patients with repaired tetralogy of Fallot.

 

Presentation

History

The clinical presentation of infants with tetralogy of Fallot (TOF) is included for comparison to that of adults.

Presentation of pediatric patients with tetralogy of Fallot

Most infants with tetralogy of Fallot have difficulty with feeding, and failure to thrive (FTT) is commonly observed. Infants with pulmonary atresia may become profoundly cyanotic as the ductus arteriosus closes unless bronchopulmonary collaterals are present. Occasionally, some children have just enough pulmonary blood flow and do not appear cyanotic; these individuals remain asymptomatic, until they outgrow their pulmonary blood supply.

At birth, some infants with tetralogy of Fallot do not show signs of cyanosis, but they may later develop episodes of bluish pale skin during crying or feeding (ie, "Tet" spells). Hypoxic tet spells are potentially lethal, unpredictable episodes that occur even in noncyanotic patients with tetralogy of Fallot. The mechanism is thought to include spasm of the infundibular septum, which acutely worsens the right ventricular (RV) outflow tract obstruction (RVOTO). These spells can be aborted with relatively simple procedures.

A characteristic fashion in which older children with tetralogy of Fallot increase pulmonary blood flow is to squat. Squatting is a compensatory mechanism, of diagnostic significance, and highly typical of infants with tetralogy of Fallot. Squatting increases peripheral vascular resistance (PVR) and thus decreases the magnitude of the right-to-left shunt across the ventricular septal defect (VSD). Exertional dyspnea usually worsens with age. Occasionally, hemoptysis due to rupture of the bronchial collaterals may result in the older child.

The rare patient may remain marginally and imperceptibly cyanotic, or acyanotic and asymptomatic, into adult life.

Cyanosis generally progresses with age and outgrowth of pulmonary vasculature and demands surgical repair. The following factors can worsen cyanosis in infants with tetralogy of Fallot:

  • Acidosis

  • Stress

  • Infection

  • Posture

  • Exercise

  • Beta-adrenergic agonists

  • Dehydration

  • Closure of the ductus arteriosus

The predominant shunt is from right to left with flow across the VSD into the left ventricle (LV), which produces cyanosis and an elevated hematocrit value. When the pulmonary stenosis is mild, bidirectional shunting may occur. In some patients, the infundibular stenosis is minimal, and the predominant shunt is from left to right, producing what is called a pink tetralogy. Although such patients may not appear cyanotic, they often have oxygen desaturation in the systemic circulation.

Symptoms generally progress secondary to hypertrophy of the infundibular septum. Worsening of the RVOTO leads to RV hypertrophy, increased right-to-left shunting, and systemic hypoxemia.

Presentation of the adult with tetralogy of Fallot

The clinical features of tetralogy of Fallot (TOF) in the adult are directly related to the severity of the anatomic defects. 

Even after surgery it is important to understand that despite the curative approach to surgery, it is simply a long-term palliative procedure. The surgery only corrects the anatomic abnormality; it does not address the cause and does not prevent the ongoing anatomic changes in the RV and pulmonary vessels. Hence, sooner or later, most patients with corrective surgery will present with some type of symptom related to dysfunction of the RV and RVOTO.[21]

The majority of patients with repaired tetralogy of Fallot remain symptom free for at least the first two decades following the initial surgery. Mild pulmonary valve insufficiency may appear after the second decade of life and is often asymptomatic. However, with time, the pulmonary valve insufficiency become severe and patients do become symptomatic. Chief complaints at that time may include lack of exercise endurance, palpitations, and a gradual decline in bodily functions.

Physical Examination

As tetralogy of Fallot (TOF) progresses in adults, exertional dyspnea, syncope, palpitations, and evidence of right heart failure such as elevated jugular venous pressure (JVP), ascites, peripheral edema, and hepatomegaly may be noted. Closer examination may also reveal the presence of a large "A wave" in the JVP tracing. This A wave occurs as a result of atrial contraction in late diastole; an abnormally large A wave is typically visible to the eye and denotes increased resistance to right atrial emptying as a result of right ventricular (RV) hypertrophy, which can be seen in severe pulmonary stenosis.

Auscultation

Auscultation of the chest for pulmonary valve insufficiency will reveal a low-pitched, short diastolic murmur. This murmur is often difficult to hear in most individuals as it has a very short duration, even when the insufficiency is severe; thus the pathology may be missed on the physical examination. Some patients may have an extra heart sound—an ejection click as a result of a dilated ascending aorta. In addition, some patients may have a murmur due to aortic regurgitation.

If RV outflow tract obstruction is present, an audible murmur is usually noted. In addition, the presence of a residual ventricular septal defect will reveal a loud pansystolic murmur.

If the pulmonary valve insufficiency is not identified, it gradually leads to RV dysfunction and the onset of arrhythmias. The majority of adult patients with tetralogy of Fallot need corrective surgery to repair or replace the pulmonary valve.

 

DDx

Diagnostic Considerations

When an adult with tetralogy of Fallot (TOF) presents, a wide variation exists in their clinical signs and symptoms, primarily owing to differences in the basic anatomic morphology of the heart and the types of surgical repair performed in infancy. Moreover, the pathophysiology of this condition primarily depends on the severity of the right ventricular (RV) outflow tract obstruction (RVOTO). In turn, RVOTO determines the severity of the right-to-left shunting, which is typical.

Two key reasons for why some individuals with tetralogy of Fallot present much later in life are 1) the perimembranous ventricular septal defect (VSD) is small (whereas it is usually quite large in children) and 2) the RVOTO is mild. For those who already underwent surgery in childhood, the most common reason for later presentation is pulmonary valve regurgitation. However, other disorders that also should be considered when evaluating an adult patient with tetralogy of Fallot include the following:

  • Endocarditis

  • Cerebral embolism

  • Cardiogenic shock

  • Pulmonary atresia

  • VSD

  • Lung disorders (eg, asthma, reactive airway disease)

  • Right heart failure

Differential Diagnoses

 

Workup

Approach Considerations

See also the Guidelines section for the 2018 American Heart Association/American College of Cardiology (AHA/ACC) recommendations for the management of adults with tetralogy of Fallot.

Laboratory studies

Laboratory studies that may be helpful in the evaluation of adult patients with tetralogy of Fallot (TOF) include the following:

  • Complete blood cell (CBC) count: Some patients may have a mild anemia, but if cyanosis is absent, polycythemia is rare.

  • Coagulation profile: This may be abnormal in patients with cyanosis and bleeding.

  • Arterial blood gas (including serum lactate, base excess, oxygen partial pressure [PO2]): The patient's oxygenation status, serum lactate levels, and base excess value appear to be prognostic markers for mortality in those undergoing surgical repair of tetralogy of Fallot.[4]

  • Blood cultures: Obtain blood cultures in febrile patients to rule out endocarditis or sepsis.

Electrocardiography

The electrocardiogram (ECG) will usually show the presence of right ventricular (RV) hypertrophy with a right bundle branch block. The longer the QRS interval, the larger will be the RV mass and volume. Furthermore, when the QRS interval is longer than 180 milliseconds (ms), it is a significant marker for the development of ventricular arrhythmias and sudden death.[22]

Another ECG feature that is also known to predict the risk for ventricular arrhythmias and sudden death is the rate of change in the QRS interval. A relatively fast increase (>3.5 ms/year) is associated with a higher risk of death. A rapid change in the rate of change is also a significant event in the absence of prolongation of the QRS interval. Finally, variation in the heart rate is also a marker for sudden death in these patients.[22]

In other patients, the ECG will reveal atrial tachycardia or atrial fibrillation.

Cardiac catherization

When adults with tetralogy of Fallot (TOF) present, the initial study of choice is usually echocardiography. However, in some cases, cardiac catheterization is needed to assess the pressures in the right ventricle and pulmonary artery, the location and size of the ventricular septal defect, and the status of the pulmonary vessels. Cardiac catheterization is also necessary when the cardiac anatomy cannot be completely defined by echocardiography, when disease in the pulmonary arteries is a concern, and if an anomalous coronary artery or pulmonary hypertension is suspected.

Imaging Studies

Imaging studies used in the evaluation of tetralogy of Fallot (TOF) includechest radiographs, magnetic resonance imaging (MRI), and echocardiography.

Radiography

The chest x-ray may be normal, or it may show cardiomegaly and prominent right ventricular (RV) shadowing. Although the hallmark of tetralogy of Fallot in infants is the classic boot-shaped heart (coeur en sabot) (see the following image), in which diminished vascularity in the lungs and diminished prominence of the pulmonary arteries become apparent, this classic shape of the heart is not always seen in adults with tetralogy of Fallot.

An uplifted apex and absence of pulmonary artery s An uplifted apex and absence of pulmonary artery segment typifies the "coeur en sabot" (ie, boot-shaped heart) of tetralogy of Fallot.

Echocardiography

Color-flow echocardiography is always obtained in adult patients tetralogy of Fallot to assess the overall cardiac function and the status of the valves, and for the presence of any residual ventricular septal defect (VSD), ductus arterosus, or atrial septal defect. Note that although echocardiography can assess the valvular anatomy, it is unable to visualize the coronary anatomy in the adult patient. This imaging modality is also able to reveal the grade and severity of any RV outflow tract (RVOT) obstruction.

Magnetic resonance imaging

MRI has become the gold standard for assessing the RV function and size, as well as for quantifying the pulmonary regurgitant volume. When a problem with the pulmonary valve is suspected, MRI is the first test of choice. This imaging modality can map the velocity of pulmonary regurgitation and provides good delineation of the aorta size as well as assessment of the pulmonary arteries, the status of the RVOT, and the presence of VSDs and/or RV hypertrophy.[5]  MRI can also measure intracardiac pressures, gradients, and blood flows.

MRI is quite sensitive at detecting branch pulmonary artery stenosis, which may be contributing to the increasing pulmonary valve insufficiency and the formation of aortopulmonary collaterals. These findings are more common in those with tetralogy of Fallot who have pulmonary atresia.[23, 24]

Screening

Some pediatric cardiology centers specialize in looking after patients with tetralogy of Fallot. They recommend a baseline MRI of the the heart, even in the absence of symptoms. The results can then be used to monitor the patient for any changes every 3-7 years.

 

Treatment

Approach Considerations

Most symptomatic adults with tetralogy of Fallot (TOF) require some type of surgical procedure, of which pulmonary valve replacement is the most common (usually performed under cardiopulmonary bypass).

In general, the majority of adult patients with tetralogy of Fallot are managed with elective surgery. Unlike infants with this condition, emergency surgery is very rare in the adult patient population. Once the diagnosis of pulmonary valve insufficiency is established, the patient is referred to the surgeon. Because the repair surgery is considered a "redo" surgery, albeit many years after the initial procedure, the surgeon will perform an exhaustive workup to ensure that the patient has a complication-free procedure.

In tetralogy of Fallot, the right ventricle (RV) can be dilated and hypertrophied and, hence, it may adhere to the posterior sternum. This is vital information to know before opening the chest with the mechanical saw. Thus, obtain a lateral chest x-ray to confirm this finding. If the RV is adhered to the posterior sternum, the surgeon may opt to have the patient go on bypass via the groin vessels, decompress the heart, and then open the chest with an oscillating saw. Once the chest is opened, the rest of the procedure is like that of any open heart surgery.

Risk factors for surgery in adults with tetralogy of Fallot

Factors that increase the risk for surgery in adult patients with tetralogy of Fallot include the following:

  • Cardiogenic shock

  • Poor RV function

  • Diminutive pulmonary arteries

  • Other major associated anomalies, such as tricuspid atresia or an anomalous coronary artery

  • Multiple previous surgeries

  • Advanced age

  • Severe annular hypoplasia

  • High peak RV–to–left ventricular pressure ratio

  • Multiple ventricular septal defects (VSDs)

  • Right-sided heart failure

See also the Guidelines section for the 2018 American Heart Association/American College of Cardiology (AHA/ACC) recommendations for the management of adults with tetralogy of Fallot.

Medical Treatment

There is no effective medical treatment for pulmonary insufficiency. Although afterload-reducing agents and diuretics have been attempted, most patients with tetralogy of Fallot (TOF) with pulmonary insufficiency do not show any benefit and the condition continues to progress. If the pulmonary artery pressures are high, some cardiologists place the patient on sildenafil. But long-term studies are lacking on the benefits of this agent in adult patients with tetralogy of Fallot.

For those adults who develop acute cyanosis, place them in a knee-chest position. In addition, provide oxygen and administer intravenous (IV) morphine. IV propranolol can be used in severe cases, as it is known to relax the infundibular muscle spasm and relieve the right ventricular outflow tract obstruction.[6]

Pulmonary vasodilator drugs

Research is being conducted on drugs that can dilate the pulmonary vasculature and lower the pulmonary insufficiency. Initial studies using nitric oxide suggest that such a strategy may be effiective. Sildenafil has been used to treat such patients,[25] but there are no long-term studies to determine if this agent can prevent progression of the pulmonary insufficiency.

Surgical Treatment

Primary correction in infants is the ideal operation for treatment of tetralogy of Fallot (TOF), and it is usually performed under cardiopulmonary bypass (CPB). The aims of the surgery in this population are to close the ventricular septal defect (VSD), resect the area of infundibular stenosis, and relieve the right ventricular (RV) outflow tract (RVOT) obstruction.

Before cardiopulmonary bypass is initiated, previously placed systemic-to-pulmonary artery shunts are isolated and taken down. Patients then undergo cardiopulmonary bypass. Associated anomalies, such as atrial septal defect (ASD) or patent foramen ovale (PFO), are closed.

Surgery for adults with tetralogy of Fallot

Before any surgery is undertaken, the risks of the procedure must be weighed against the benefits. If the patient is not adequately worked up and the patient has irreversible RV dysfunction, surgery will be futile and nothing short of a transplant will be lifesaving.

Surgery to repair tetralogy of Fallot in adults is usually performed under cardiopulmonary bypass using cardioplegia. Once the heart is arrested, the VSD is closed with a patch, the infundibulum is widened, and the pulmonary valve is repaired. Unlike in infants, transannular patching is rarely performed in adult patients because this procedure often leads to pulmonary insufficiency later in life. Currently, most surgeons replace or repair the pulmonary valve in adults rather than performing a transannular patch.

The ideal treatment for pulmonary valve insufficiency is pulmonary valve replacement, which can help decrease the RV size as well as improve RV function over the long term. In general, however, the incidence of arrhythmias remains unchanged.[26]

Timing of surgery in adults with tetralogy of Fallot

Although it is no longer in question that adult patients with pulmonary valve insufficiency require surgery, there is still some debate over when the surgery should take place. Previously, surgery was usually recommended based on the presence of whether the QRS interval was longer than 180 milliseconds on electrocardiography (ECG). More recently, some surgeons believe that pulmonary valve replacement is only necessary when there is evidence of RV dysfunction. Others state that it should be performed when the patient is symptomatic. Still others opine that earlier surgery based on echocardiographic findings irrespective of symptoms is appropriate. 

In addition, conflicting arguments exist about whether to undertake surgery early or late. The general consensus is that waiting for symptoms to develop before undertaking surgery may be too late and the RV may then become irreversibly damaged. Nevertheless, regardless of the existing debate, the pulmonary valve should be replaced before heart failure develops. However, if the patient has no symptoms and has only mild RV dilatation and normal RV function, then no surgery is indicated.[27]

Mechanical versus bioprosthetic replacement valves

Once the decision has been made to perform the surgery, the next step is to select the type of prosthetic valve. Because the right side of the heart and pulmonary artery vessels are a low-flow system, insertion of a mechanical prosthetic valve is associated with a very high risk of thrombosis. Patients will require lifelong anticoagulation, which also exposes them to a risk of bleeding in case of trauma. In addition, women who become pregnant may not be able to receive warfarin because of its teratogenic effects.[28]

Most often, surgeons implant a bioprosthetic valve, of which two types are available: human tissue (homografts) or animal tissue (bovine pericardium or porcine heart valve). Both types of  valves can be implanted as solo valves or as part of a conduit in the RVOT.

Although bioprosthetic valves eliminate the need for lifelong anticoagulation, they are not durable in young patients, which is a major concern. Most adults with tetralogy of Fallot are still young (second or third decade of life). In addition, nearly 40-55% of bioprosthetic valves fail within the first decade after implantation, almost guaranteeing that an otherwise healthy 30-40-year-old patient will need to undergo one or more open heart procedure(s) in the future, which also increases the risk of complications.

Automatic implantable cardioverter defibrillator

Some patients continue to have ventricular arrhythmias despite surgical repair; they are at greater risk for sudden death. These patients may benefit from placement of an automatic implantable cardioverter defibrillator (AICD). The procedure can be performed under local anesthesia and is relatively safe.[29]

Radiofrequency ablation

Relatively recently, the use of radiofrequency ablation (RFA) has become another option to treat arrhythmias in adult patients with tetralogy of Fallot. This technique may help to resolve atrial or ventricular arrhythmias.[1, 2, 30]

Postoperative Monitoring and Results

All infants who undergo open-heart procedures are sent to the pediatric intensive care unit (PICU). with close monitoring of hemodynamic parameters. One study of children who underwent complex open heart surgery procedures found short-term outcome may be predicted by the amount of inotropic and pressor support received in the ICU. The greater the support, the worse the outcome.[31] All infants initially remain intubated on a ventilator until cardiac and respiratory statuses stabilize. To maintain systemic peripheral perfusion, adequate cardiac output and atrial pacing may be required. Patients are weighed daily to follow volume status. Those with heart block typically have temporary atrioventricular (AV) pacing; if intrinsic conduction has not returned in 5-6 days, the patient probably needs a permanent pacemaker.

Revision/reoperation

The literature suggests that approximately 5% of individuals with tetralogy of Fallot (TOF) who underwent repair in childhood will need a revision/reoperation at some point. Indications for early reoperation include a residual ventricular septal defect (VSD) or a residual RV outflow tract obstruction (RVOTO).

Residual VSDs are poorly tolerated in patients with tetralogy of Fallot because these individuals cannot tolerate an acutely imposed volume overload. Small, residual VSDs are common after surgical repair and are usually clinically insignificant. In a cross-sectional prospective study that evaluated the effect of volume overload on global and regional RV and left ventricular (LV) deformation, and their relationships with conventional diagnostic parameters, Menting et al reported a reduction in RV free strain and strain rate in adults late after repair of tetralogy of Fallot, with the apical segment particularly affected.[32] LV septal strain also decreased, which the investigators suggested was likely due to mechanical coupling of the ventricles in which RV dysfunction negatively impacted LV function.[32]

A residual VSD with a 2:1 shunt or an RVOTO of greater than 60 mm Hg is an urgent indication for reoperation. Surgery can be performed with low risk and can result in dramatic improvements. Occasionally, pulmonary valve insufficiency may increase and may be associated with RV failure.

Once tetralogy of Fallot has been repaired in infancy or childhood, about 5% of individuals require repair or replacement of the pulmonary valve. Because of better surgical results in the present era, long-term survivors are increasingly reported. In most of these individuals, pulmonary regurgitation is the clinical presentation and can be treated with a prosthetic tissue valve.[33]

Porcine valves are preferred over mechanical valves because they have lesser tendency to thrombose.

Results in adults with tetralogy of Fallot

The few surgical series on adults patients report varying postsurgical results, with mortality ranging from 6% to 10%. After pulmonary valve replacement, some studies have shown a 5-year survival in excess of 90% and 86% at 10 years. However, although the short-term results after pulmonary valve replacement are good to excellent, the long-term outcomes are poor to fair.[34, 35, 36]  

In almost all case series, a number of patients have required redo procedures and/or pacemaker insertion, and some individuals have persistently elevated RVOT pressures. Others have even required re-replacement of their porcine valves.

Postoperative follow-up of adults with tetralogy of Fallot has shown that the pulmonary valve replacement also slows down or reverses the progression of some complications associated with pulmonary valve insufficiency, including RV dysfunction and tricuspid regurgitation. However, whether the surgery ameliorates the ventricular arrhythmias remains in debate. Some short-term studies reveal that there is a low incidence of arrhythmias in the postoperative period, but other long-term studies have not shown any difference. In general, arrhythmias continue to persist even after surgery in a number of patients tetralogy of Fallot who've undergone pulmonary valve replacement.[37]

Surgical Complications

Early postoperative complications following repair of tetralogy of Fallot (TOF) include the creation of heart block and residual ventricular septal defects (VSDs). Ventricular arrhythmias are more common and are reportedly the most frequent cause of late postoperative death. Sudden death from ventricular arrhythmias has been reported in 0.5% of individuals within 10 years of repair. The arrhythmias are thought to occur in fewer than 1% of patients having an early operation. As with most heart surgery, the risk of endocarditis is lifelong, but the risk is much less than in a patient with an uncorrected tetralogy of Fallot.

Surgery to manage tetralogy of Fallot has both short and long-term complications. As is the case with most heart surgeries, the risk of endocarditis is lifelong because the patient now has a prosthetic valve.

Short-term postoperative complications include the following:

  • Rebleeding

  • Tamponade

  • Persistent elevation in right ventricular (RV) pressures

  • Right heart failure

  • Sternal wound infection

  • Atrial arrhythmias

Long-term postoperative complications include the following:

  • Pulmonary valve insufficiency

  • Persistent RV outflow tract obstruction

  • Atrial and ventricular arrhythmias

  • Right heart failure

Long-Term Monitoring

It was previously believed that surgery for tetralogy of Fallot was curative; it is now acknowledged that even after primary repair, a fair number of individuals who underwent surgery as children will present as adults with symptoms of pulmonary valve insufficiency and arrhythmias. In the past, many of these children with repaired tetralogy of Fallot were lost to follow-up or never followed up because of the erroneous belief that their heart condition was cured.

It is currently recommended that all children with tetralogy of Fallot be followed closely, because many will present with symptoms in their third decade of life. Some pediatric cardiology centers specialize in looking after patients  with tetralogy of Fallot; they recommend a baseline magnetic resonance imaging of the heart even in the absence of symptoms. The results can then be used to monitor the patient for any changes every 3-7 years.

The Future

In the present day, some patients with tetralogy of Fallot survive for longer than 15-20 years after their first operation. The major problem encountered by these individuals is the development of pulmonary valvular regurgitation. It appears that a number of these individuals require pulmonary valve replacement.[38] Most individuals receive a pericardial homograft, and only time will tell how long these valves will last. However, the last decade has seen great advances in percutaneous technology and tissue engineering, and perhaps the role of surgery may decline.[39]

Percutaneous valve replacement

With innovations in endovascular technology, the potential for percutaneous pulmonary valve replacement is becoming a reality in the near future. For example, the Melody transcatheter pulmonary valve can be implanted percutaneously (see the image below) via the femoral vein, guided by fluoroscopy; early case reports indicate that the technique is feasible and safe. These few case reports reveal that after valve implantation, there is a moderate reduction in pulmonary valve insufficiency and the ventricular size,  as well as marked improvement in exercise tolerance. Thus far, the Melody valve is the only one approved for use through a humanitarian device exemption protocol for patients with a prior pulmonary artery conduit who now have developed pulmonary insufficiency or stenosis. If future studies regarding transcatheter pulmonary valve implantation prove to be durable, this may change how tetralogy of Fallot in adults is managed.[40] ​[41, 42]

Melody pulmonary valve. Melody pulmonary valve.
 

Guidelines

Guidelines Summary

2018 AHA/ACC guidelines

The American Heart Association/American College of Cardiology (AHA/ACC) released updates to their 2008 guideline for the management of adults with congenital heart disease (CHD) in August 2018.[43, 43] Their recommendations for tetralogy of Fallot (TOF) are outlined below.

Management and care of patients with tetralogy of Fallot (repaired or unrepaired) should involve a cardiology with expertise in CHDs. Interventions involving congenital heart lesions (cardiac surgery, catheter-based interventional cardiac procedures, electrophysiologic procedures) in adults with CHD should be performed by those with expertise in adult CHD procedures as well as that of a cardiologist specializing in adult CHD.

The AHA/ACC antomic/physiologic (AP) classification categorizes repaired tetralogy of Fallot to be of moderate complexity.

Experts in imaging with ultrasonography, echocardiography, and cardiac magnetic resonance imaging (CMRI) are preferred for cardiac imaging in patients with tetralogy of Fallot. 

Use a standard 12-lead electrocardiogram (ECG) in adults with CHD with serial assessment based on the specific CHD AP classification or when symptoms develop or worsen. Use ambulatory ECG monitoring in patients with CHD who are at risk for tachyarrhythmia, bradyarrhythmia or heart block, of when symptoms of a potential arrhythmic etiology develop.

Use ECG to measure QRS duration in patients following repair of tetralogy of Fallot and as part of the evaluation for cardiac resynchronization therapy (CRT).

CMRI, cardiac computed tomography (CCT) scanning, transesophageal echocardiography (TEE), and/or cardiac catherization may be superior to transthoracic echocardiography (TTE) in the assessment of right ventricular (RV) size and function in repaired tetralogy of Fallot, systemic RVs, and other conditions associated with RV volume and pressure overload.

Tetralogy of Fallot among other cardiac findings is commonly associated with DiGeorge (velocardiofacial syndrome) and Down syndromes.

Diagnostic recommendations

CMRI is useful for quantification of ventricular size and function, pulmonary valve function, pulmonary artery (PA) anatomy, and left heart abnormalities in patients with repaired tetralogy of Fallot.

Obtain coronary artery compression testing before performing right ventricle-to-PA conduit stenting or transcatheter valve placement in repaired tetralogy of Fallot.

Programmed ventricular stimulation can be useful for risk stratification of adults with tetralogy of Fallot and additional risk factors for sudden cardiac death (SCD).

In patients with repaired tetralogy of Fallot, cardiac catheterization with angiography, if indicated, is reasonable to assess hemodynamics when adequate data cannot be obtained noninvasively in the setting of an arrhythmia, heart failure, unexplained ventricular dysfunction, suspected pulmonary hypertension, or cyanosis.

Therapeutic recommendations

Pulmonary valve replacement (surgical or percutaneous) for symptomatic relief is recommended for patients with repaired tetralolgy of Fallot and moderate or greater pulmonary regurgitation (PR) with otherwise unexplained cardiovascular symptoms.

Pulmonary valve replacement (surgical or percutaneous) is reasonable for preservation of ventricular size and function in asymptomatic patients with repaired tetralogy of Fallot and ventricular enlargement or dysfunction and moderate or greater PR.

Primary prevention with implantable cardioverter-defibrillator (ICD) therapy is reasonable in adults with tetralogy of Fallot and multiple risk factors for SCD.

Surgical pulmonary valve replacement may be reasonable for adults with repaired tetralogy of Fallot and moderate or greater PR with other lesions that require surgical interventions.

Consider pulmonary valve replacement, in addition to arrhythmia management, for adults with repaired tetralogy of Fallot and moderate or greater PR and ventricular tachyarrhythmia.

RV-to-PA conduit

Diagnostic recommendations

Coronary artery compression testing with simultaneous coronary angiography and high-pressure balloon dilation in the conduit is indicated before RV-to-PA conduit stenting or transcatheter valve placement.

In patients with stented RV-to-PA conduits and worsening pulmonary stenosis (PS) or PR, evaluate for conduit complications, including fluoroscopy to evaluate for stent fracture and blood cultures to assess for infective endocarditis.

In adults with RV-to-PA conduit and arrhythmia, congestive heart failure, unexplained ventricular dysfunction, or cyanosis, cardiac catheterization is reasonable to assess the hemodynamics. 

Therapeutic recommendations

RV-to-PA conduit intervention is reasonable for adults with RV-to-PA conduit and moderate or greater PR or moderate or greater stenosis with reduced functional capacity or arrhythmia.

RV-to-PA conduit intervention may be reasonable for asymptomatic adults with RV-to-PA conduit and severe stenosis or severe regurgitation with reduced RV ejection fraction or RV dilatation. 

 

Medication

Medication Summary

The goals of tetralogy of Fallot (TOF) therapy are to reduce the ventilatory drive, increasing systemic venous return, and to increase peripheral vascular resistance.

Analgesics

Class Summary

Analgesic agents reduce ventilatory drive. In addition, pain control ensures patient comfort and promotes pulmonary toilet. Most analgesic agents have sedating properties, which are beneficial for patients who are having hypercyanotic episodes.

Morphine sulfate (Duramorph, Astramorph, MS Contin)

Morphine is the drug of choice (DOC) for narcotic analgesia because of its reliable and predictable effects, safety profile, and ease of reversibility with naloxone.

This agent is administered intravenously (IV), may be dosed in number of ways, and is commonly titrated until the desired effect is obtained.

Alpha-adrenergic Agonists

Class Summary

Alpha-adrenergic agents improve hemodynamic status by improving myocardial contractility and increasing heart rate, resulting in increased cardiac output. Peripheral resistance is increased by vasoconstriction, increased cardiac output, and elevated blood pressure.

Phenylephrine

Phenylephrine is a strong postsynaptic alpha-receptor stimulant with little beta-adrenergic activity. This drug produces vasoconstriction of arterioles, thereby increasing peripheral venous return.

 

Questions & Answers

Overview

What is tetralogy of Fallot (TOF)?

What are the signs and symptoms of tetralogy of Fallot (TOF) in adults?

What are the signs and symptoms of tetralogy of Fallot (TOF) in infants?

Which physical findings are characteristic of tetralogy of Fallot (TOF) in adults?

Which lab tests are performed in the workup of tetralogy of Fallot (TOF) in adults?

Which imaging studies are performed in the workup of tetralogy of Fallot (TOF)?

Which findings on chest radiograph are characteristic of tetralogy of Fallot (TOF)?

What are the indications for echocardiography in the workup of tetralogy of Fallot (TOF)?

What is the role of MRI in the workup of tetralogy of Fallot (TOF)?

What are the indications for cardiac catheterization in the workup of tetralogy of Fallot (TOF)?

How is acute cyanosis treated in patients with tetralogy of Fallot (TOF)?

Which factors increase the risk for surgical repair of tetralogy of Fallot (TOF)?

How is tetralogy of Fallot (TOF) classified?

What are the typical features of tetralogy of Fallot (TOF)?

What is the role of surgery in the treatment of tetralogy of Fallot (TOF) in infants?

What is the efficacy of surgical repair of tetralogy of Fallot (TOF) in infancy?

How was tetralogy of Fallot (TOF) first identified and treated?

What are the anatomic features of tetralogy of Fallot (TOF) in adults?

What are the anatomic characteristics of the aorta in adults with tetralogy of Fallot (TOF)?

What are the anatomic characteristics of RVOTO in adults with tetralogy of Fallot (TOF)?

What are the anatomic characteristics of the pulmonary arteries in adults with tetralogy of Fallot (TOF)?

What are the associated heart defects in adults with tetralogy of Fallot (TOF)?

What is the pathophysiology of tetralogy of Fallot (TOF) in children?

What is the pathophysiology of tetralogy of Fallot (TOF) in adults?

What is the role of arrhythmias in the pathogenesis of tetralogy of Fallot (TOF)?

What is the prevalence of tetralogy of Fallot (TOF)?

What is the prognosis of tetralogy of Fallot (TOF)?

What are the possible complications of a repaired tetralogy of Fallot (TOF) in adults?

Presentation

Which clinical history findings are characteristic of tetralogy of Fallot (TOF) in infants?

Which factors may worsen cyanosis in infants with tetralogy of Fallot (TOF)?

Which clinical history findings are characteristic of tetralogy of Fallot (TOF) in adults?

Which physical findings are characteristic of tetralogy of Fallot (TOF) in adults?

Which auscultation findings are characteristic of tetralogy of Fallot (TOF)?

DDX

Which conditions are included in the differential diagnoses of tetralogy of Fallot (TOF)?

What are the differential diagnoses for Tetralogy of Fallot (TOF) in Adults?

Workup

What is the role of lab testing in the workup of tetralogy of Fallot (TOF) in adults?

What is the role of ECG in the workup of tetralogy of Fallot (TOF)?

What is the role of cardiac catheterization in the workup of tetralogy of Fallot (TOF)?

What is the role of imaging studies in the workup of tetralogy of Fallot (TOF)?

What is the role of radiography in the workup of tetralogy of Fallot (TOF)?

What is the role of echocardiography in the workup of tetralogy of Fallot (TOF)?

Why is MRI the gold standard for assessing tetralogy of Fallot (TOF) in adults?

What is the role of MRI in tetralogy of Fallot (TOF) screening?

Treatment

How is tetralogy of Fallot (TOF) treated in adults?

What is the role of medications in the treatment of tetralogy of Fallot (TOF)?

What is the role of pulmonary vasodilator drugs in the treatment of tetralogy of Fallot (TOF)?

How is tetralogy of Fallot (TOF) treated in infants?

How is surgical treatment of tetralogy of Fallot (TOF) performed in adults?

When is surgical treatment of tetralogy of Fallot (TOF) performed in adults?

What are the differences between mechanical and bioprosthetic replacement valves for tetralogy of Fallot (TOF)?

What is the role of automatic implantable cardioverter defibrillator in the treatment of tetralogy of Fallot (TOF)?

What is the role of radiofrequency ablation in the treatment of tetralogy of Fallot (TOF)?

What is included in postoperative care following surgical repair of tetralogy of Fallot (TOF) in infants?

What are the indications for early reoperation for the repair of tetralogy of Fallot (TOF)?

How frequently is repair or replacement of the pulmonary valve required following surgical repair of tetralogy of Fallot (TOF) in infancy?

What are the reported outcomes for the surgical repair of tetralogy of Fallot (TOF) in adults?

What are the possible complications of tetralogy of Fallot (TOF) surgical repair?

What does long-term monitoring for tetralogy of Fallot (TOF) involve?

What is the survival rate of tetralogy of Fallot (TOF)?

What is the role of percutaneous valve replacement in the treatment of tetralogy of Fallot (TOF)?

Guidelines

What are the AHA/ACC guidelines on tetralogy of Fallot (TOF) in adults?

What are the AHA/ACC diagnostic guidelines for tetralogy of Fallot (TOF) in adults?

What are the AHA/ACC treatment guidelines for tetralogy of Fallot (TOF) in adults?

What are the AHA/ACC guidelines on the evaluation of the right ventricle-pulmonary artery (RV-PA) conduit in tetralogy of Fallot (TOF)?

What are the AHA/ACC guidelines on the use of the right ventricle-pulmonary artery (RV-PA) conduit in the treatment of tetralogy of Fallot (TOF)?

Medications

What is the goal of tetralogy of Fallot (TOF) therapy?

Which medications in the drug class Alpha-adrenergic Agonists are used in the treatment of Tetralogy of Fallot (TOF) in Adults?

Which medications in the drug class Analgesics are used in the treatment of Tetralogy of Fallot (TOF) in Adults?