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Tetralogy of Fallot


Tetralogy of Fallot (TOF) is a congenital disorder of the heart. It is made up of four anatomical malformations, hence the prefix tetra, which denotes a four part event. The anomalies are ventricular septal defect (VSD), pulmonary infundibular stenosis, right ventricular hypertrophy and overriding aorta.


One of the commonest presenting complain is failure to thrive and this results from difficulty in feeding due to dyspnea. Infants typically develop cyanosis and the severity is related to the degree of stenosis [7]. Sometimes these infants only develop these signs when they cry or feed in a phenomenon known as Tet spells. Older children with this condition squat a lot as squatting increases pulmonary blood flow by increasing peripheral vascular resistance. Dyspnea on exertion worsens with age and older children may rupture some bronchial collaterals which will cause hemoptysis [8].

Physical exam will reveal a small for age baby, cyanosis, finger clubbing in older children, heart murmurs typically a systolic ejection murmur, scoliosis, bulging left hemithorax, palpable right ventricle and retinal engorgement.

Atrial Septal Defect
  • Preoperative echocardiography was diagnostic of tetralogy of Fallot with an atrial septal defect of the primum type, unroofed coronary sinus, and a left superior vena cava draining into the left atrium.[ncbi.nlm.nih.gov]
  • Abstract This report describes a rare case of Tetralogy of Fallot with associated left superior vena cava and coronary sinus atrial septal defect. The initial diagnosis was made by echocardiography.[ncbi.nlm.nih.gov]
  • Do you have a child between 30 days and 17 years old who will have elective surgery to close an atrial septal defect? This study tests a tool that allows surgeons to tell the difference between various types of heart tissue and avoid injury.[nhlbi.nih.gov]
Cyanotic Congenital Heart Disease
  • Abstract Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease and can occur in the setting of chromosomal aberrations or multisystem malformation syndromes.[ncbi.nlm.nih.gov]
  • Abstract Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease, with a familial recurrence risk of 3%.[ncbi.nlm.nih.gov]
  • Introduction - Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart disease (CHD).[ncbi.nlm.nih.gov]
  • Abstract Tetralogy of Fallot (TOF) is one of the most severe forms of cyanotic congenital heart disease (CHD) and is also the most common.[ncbi.nlm.nih.gov]
  • Abstract: This book covers the most common form of cyanotic congenital heart disease, one of the first to be successfully repaired by heart surgeons. The text explores monitoring and treatment of adults, Read more...[worldcat.org]
Congestive Heart Failure
  • Drugs that help to remove excess fluid from the body (diuretics), dietary salt restriction, and bed rest may be effective in treating congestive heart failure.[rarediseases.org]
  • Major factors were congestive heart failure and schizophrenia in one patient (#17 in Table 1, died suddenly) and schizophrenia in the other (#15 in Table 1, with repeated admissions).[nature.com]
  • In addition, this approach avoids the risks of pulmonary artery shunting with its inherent risks, namely shunt thrombosis, congestive heart failure, pulmonary artery distortion, or pulmonary vascular disease.[circ.ahajournals.org]
  • Finally, for patients with mild disease, with so‐called “pink tetralogy” due to the lack of cyanosis, their presentation may consist of signs and symptoms of congestive heart failure due to the left‐to‐right shunting across the VSD and subsequent pulmonary[pedclerk.bsd.uchicago.edu]
  • 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[emedicine.com]
Respiratory Distress
  • We report a male infant with these combined anomalies who presented with severe cyanosis, heart failure, and respiratory distress after birth.[ncbi.nlm.nih.gov]
  • Fetuses with this combined condition who survive through birth typically need intervention in infancy or early childhood because of respiratory distress, heart failure, or failure to thrive.[ncbi.nlm.nih.gov]
  • Discontinuation of life: ethical and legal issues -- Respiratory complications: acute respiratory distress syndrome, chylothorax, diaphragmatic palsy, and functional and respiratory physiotherapy -- Gastrointestinal complications: necrotizing enterocolitis[worldcat.org]
  • The past few days he has had poor feeding and recurrent episodes of respiratory distress associated with ‘turning blue’. He was diagnosed with Tetralogy of Fallot antenatally and was born at term (a normal vaginal birth).[lifeinthefastlane.com]
  • Most patients will present in the neonatal period with mild-to-moderate cyanosis, but typically without respiratory distress.[ncbi.nlm.nih.gov]
Heart Disease
  • To participate in this study, you must be an adult with congenital heart disease with or without a family member with congenital heart disease. This study is located in Columbus, Ohio.[nhlbi.nih.gov]
  • Cyanosis is an important sign of tetralogy of Fallot. Cyanosis is a bluish tint to the skin, lips, and fingernails. Low oxygen levels in the blood cause cyanosis. Babies who have unrepaired tetralogy of Fallot sometimes have "tet spells."[web.archive.org]
  • This leads to cyanosis (a bluish-purple color to the skin).[nlm.nih.gov]
  • There may be permanent cyanosis. Also found in cattle and dog.[web.archive.org]
  • Typically this is significant, resulting in cyanosis evident in the neonatal period, as a result of the right to left shunt across the VSD.[web.archive.org]
Single S2
  • S2 clubbing (in older children with uncorrected defect) Imaging Radiography indication for all patients views chest findings boot-shaped heart dark lung fields Echocardiogram indication performed as the gold standard diagnostic test most sensitive test[step1.medbullets.com]
  • Single S2 - pulmonary valve closure not heard. Systolic ejection murmur - varies in intensity inversely with the degree of RVOT obstruction. Cyanotic patients have greater obstruction and a softer murmur.[patient.info]
  • There is also a loud and single S2 in TOF.[lifeinthefastlane.com]
  • Patients will have a normal S1 and possibly a single S2 due to diminished P2 component. Click on the icon below to hear the murmur of TOF: Cyanosis: If patients are cyanotic, this is most commonly seen on the lips or nail beds.[pedclerk.bsd.uchicago.edu]
Vertical Gaze Palsy
  • Paramedian thalamic infarction causing vertical gaze palsy without midbrain involvement is an infrequent finding.[ncbi.nlm.nih.gov]
Short Hands
  • Typical features of this disorder are distinctive facial appearance, deafness, intellectual disability, cardiovascular abnormalities, short stature, short hands and feet, compact build, joint stiffness, and skeletal anomalies.[ncbi.nlm.nih.gov]
Joint Stiffness
  • Typical features of this disorder are distinctive facial appearance, deafness, intellectual disability, cardiovascular abnormalities, short stature, short hands and feet, compact build, joint stiffness, and skeletal anomalies.[ncbi.nlm.nih.gov]
  • A 50-year-old man was admitted to our stroke unit for a sudden onset of left cervical pain, mild left ptosis, dysarthria, and dysphagia. His medical history was remarkable for surgically repaired ToF.[ncbi.nlm.nih.gov]


Laboratory investigations include blood tests to check the hemoglobin and hematocrit which will be elevated; arterial blood gas to show oxygen saturation, pH and partial pressure of carbon dioxide.

Radiologic studies include chest X-rays which shows a characteristic boot shaped heart, signifying right ventricular hypertrophy. MRI is also valuable as it shows vessels in addition to the heart. An echocardiogram is the mainstay in diagnosis as it demonstrates the four anatomical defects. Electrocardiograms can also be done to examine the electrical activity of the heart [9].

P Pulmonale
  • Supporting criteria Right atrial enlargement (P pulmonale). Right ventricular strain pattern ST depression / T wave inversion in the right precordial (V1-4) and inferior (II, III, aVF) leads.[litfl.com]
Right Atrial Hypertrophy
  • ECG shows right ventricular hypertrophy and may also show right atrial hypertrophy.[msdmanuals.com]


The definitive treatment of this condition is surgical correction and this is best done in the first year of life. The surgery aims to close the ventricular septal defect with the use of a patch or homograft, resect the infundibular stenosis and relieve right ventricular outflow tract obstruction. These procedures are usually done under cardiopulmonary bypass.

The two common surgical procedures are Blalock-Taussig shunt which is palliative and intracardiac repair which is definitive.

Before surgery however, medications like prostaglandins may be necessary to keep the ductus arteriosus patent. Other associated acute complications are also managed like diuretics and digitalis for heart failure [10].


The prognosis is favorable for patients who undergo surgical repair with over 90% of 20-year survival rate. The advancement of surgical techniques has seen a drastic reduction in the number of deaths. There is however a high mortality rate in those who do not undergo surgical repair. It is estimated that 50% of them would have died by the age of 6 years. Less than 20% of them reach the age of 10 years and less than half of those live beyond 20 years. Patients who survive beyond this point develop congestive cardiac failure [6].


The cause of tetralogy of Fallot, like most congenital heart diseases, is unknown. Studies however suggest a multifactorial etiology. There are prenatal factors that have been associated with an increased risk of developing tetralogy of Fallot. These include viral illnesses during pregnancy e.g rubella, mothers age greater than 40 years, maternal alcohol use, diabetes, and poor prenatal nutrition. Children born with Down syndrome and fetal hydantoin syndrome also have an increased risk of suffering from tetralogy of Fallot [2].


It is estimated that tetralogy of Fallot is responsible for 10% of all cases of congenital heart disease. It has an incidence of up to 6 in 100,000 live births and it is the most common cause of cyanotic congenital heart disease. It is responsible for approximately 33% of all congenital heart diseases in patients younger than 15 years [3].

It affects males more than females and the cases are usually sporadic with no familial association. It is associated with other extracardiac defects like hypospadias, cleft lip and palate, and craniofacial and skeletal anomalies.

Sex distribution
Age distribution


The initial defect is pulmonary infundibular stenosis which causes narrowing of the outflow tract, which limits the amount of deoxygenated blood that goes into pulmonary circulation. In response to this, the right ventricle increases the pressure with which it pumps blood into the lungs. This increased workload will lead to hypertrophy of the muscles of the right ventricle. There is also a ventricular septal defect which allows shunting of blood between both ventricles. In VSD, due to the hypertrophy of the right ventricle, the shunting is from right to left i.e. deoxygenated to oxygenated. This blood which is part deoxygenated is then pumped though the overriding aorta to the systemic circulation leading to the cyanosis that is manifested [4].

In different individuals, there is slight anatomical variation in the degree of anomalies. The severity of the outflow tract varies between patients and is responsible for severity of symptoms. In patients with smaller obstructions, as in patients with isolated VSD, the shunt is left to right and this allows the blood to go into the lungs where it can get reoxygenated [5].


There are no known guidelines for preventing this condition. Some steps may however be taken to prevent some preventable risk factors like maternal alcohol use.


Tetralogy of Fallot is a common congenital heart disorder. It is a cyanotic heart disease and is the most common cause of blue baby syndrome, a common name for methemoglobinemia in newborns. Although it comprises of four main anomalies, there could be other defects and they are all together responsible for the myriad of symptoms seen in patients with tetralogy of Fallot [1].

Patient Information

Definition: Tetralogy of Fallot (TOF) is a congenital heart defect, the baby is born with it. It is made up of 4 different defects and the severity of these defects determine the severity of the symptoms in the child.

Cause: There is no known cause. However, some maternal factors have been associated with an increased risk of the child developing TOF. They include, viral infections in pregnancy, maternal diabetes, maternal age over 40, maternal alcohol use, and poor prenatal nutrition.

Symptoms: The most common symptom us the child’s inability to feed. The growth will also be stunted as a result. There might also be blue discoloration especially of the lips and mouth (blue baby syndrome) and sometimes, this discoloration is only noticed when the child feeds or cries. Older children tend to squat a lot. There may be also be difficulty in breathing after a little exercise and coughing up blood.

Diagnosis: A series of blood tests will be required to check the blood levels including its gases. Some imaging tests like X-rays and echocardiograms will also be done to look at the size of the heart and the direction of blood flow within it.

Treatment: The main treatment is corrective surgery. This is preferably done in the first year of life and ideally not later than 2 years. Medications are given before surgery to manage circulation and also treat acute attacks.



  1. Starr JP. Tetralogy of fallot: yesterday and today. World J Surg. Apr 2010;34(4):658-68
  2. Mølgaard-Nielsen D, Pasternak B, Hviid A. Use of oral fluconazole during pregnancy and the risk of birth defects. N Engl J Med. Aug 29 2013;369(9):830-9.
  3. Perloff JK. The Clinical Recognition of Congenital Heart Disease, 4th, WB Saunders, Philadelphia 1994.
  4. Anderson RH, Weinberg PM. The clinical anatomy of tetralogy of fallot. Cardiol Young. Feb 2005;15 Suppl 1:38-47.
  5. Flanagan MF, Foran RB, Van Praagh R, et al. Tetralogy of Fallot with obstruction of the ventricular septal defect: spectrum of echocardiographic findings. J Am Coll Cardiol 1988; 11:386.
  6. Hövels-Gürich HH, Konrad K, Skorzenski D, Minkenberg R, Herpertz-Dahlmann B, Messmer BJ, et al. Long-term behavior and quality of life after corrective cardiac surgery in infancy for tetralogy of Fallot or ventricular septal defect. Pediatr Cardiol. Sep-Oct 2007;28(5):346-54.
  7. Fox D, Devendra GP, Hart SA, Krasuski RA. When 'blue babies' grow up: What you need to know about tetralogy of Fallot. Cleve Clin J Med. Nov 2010;77(11):821-
  8. Miatton M, De Wolf D, François K, Thiery E, Vingerhoets G. Intellectual, neuropsychological, and behavioral functioning in children with tetralogy of Fallot. J Thorac Cardiovasc Surg. Feb 2007;133(2):449-55.
  9. Srivastava S, Salem Y, Chatterjee S, Helen Ko H, Lai WW, Parness IA, et al. Echocardiographic Myocardial Deformation Evaluation of Right Ventricular Function in Comparison with CMRI in Repaired Tetralogy of Fallot: A Cross-Sectional and Longitudinal Validation Study. Echocardiography. Feb 2013;30(2):196-202.
  10. Aboulhosn J, Child JS. Management after childhood repair of tetralogy of fallot. Curr Treat Options Cardiovasc Med. Dec 2006;8(6):474-83.

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Last updated: 2019-07-11 21:18