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Tetralogy of Fallot


Disease: Tetralogy of Fallot Tetralogy of Fallot
Category: Cardiovascular diseases

Disease Definition:

Tetralogy of Fallot is a rare condition of infants and young children caused by structural heart defects, which cause the heart to pump oxygen-poor blood to the body. As a result, children with this condition have blue-tinged skin.


There’s a statistical probability of 0.05% for a baby to have tetralogy of Fallot. The disease is always present at birth and often diagnosed when the child is still an infant, and sometimes, according to symptoms and severity of defects, it may be diagnosed later on. Appropriate treatment after early diagnosis may grant life to most of the children with tetralogy of Fallot into adulthood.

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Symptoms, Causes


According to the extent of blood flow blockage from the right ventricle to the lungs, symptoms may vary and my include:


  • Skin coloration with shades of blue due to poor oxygen supply (cyanosis)
  • Short and rapid breath
  • Loss of consciousness (fainting)
  • Clubbing of fingers and toes (increased thickness and width to the ends of the toes and fingers)
  • Loss of appetite
  • Inadequate weight gain
  • Rapid tiring during physical activity
  • Irritability


Tet spells:

Tet spells are episodes during which babies with tetralogy of Fallot occasionally and suddenly develop deep blue skin, lips and nails; this may happen during feeding, upon awakening or after crying. This condition is caused by the rapid drop in the amount of oxygen in the blood. Squatting, which increases the blood flow to the lungs, is sometimes noticed on toddlers and older children in cases of shortness of breath. These children squat instinctively.


Four “tetra” defects in the structure of the heart are involved in the tetralogy of Fallot. These defects hinder the flow of blood to the lungs and blood mixing from the both sides of the heart, resulting in oxygen-poor blood to be pumped to the body, which leads to cyanosis in infants and children.



This condition originates during the growth of the fetus while the heart is still under development. While the exact causes are yet unknown, some factors may increase the risks such as viral illnesses, genetic disorders and poor nutrition during pregnancy. Four heart abnormalities were described in 1888 by the French physician Etienne-Louis Arthur Fallot, which were common with his patients. These were:


Pulmonary valve stenosis:

This is the case when the pulmonary valve, which is the flap between the right ventricle and the pulmonary artery, is narrowed, reducing blood flow to the lungs.


Ventrical septal defect:

This is the case when deoxegenated blood mixes with the oxygenated blood through a hole in the wall separating the two ventricals, causing deoxygenated blood to be re-pumped to the body. The ventricular septal deect can eventually weaken the heart and deprive the body from oxygenated blood.


Overriding aorta:

The aorta is the main artery that distributes the blood pumped out of the left ventricle to the body through its branches. In the case of tetralogy of Fallot, there is a slight displacement of the aorta; it is located just above the ventricular septal defect. This position allows the aorta to receive blood from both ventricles, mixing deoxygenated and oxygenated blood.


Right ventricular hypertrophy:

This is the case when the wall muscles of the right ventricle are enlarged and thickened due to the increased workload of pumping blood. This weakens the heart over time and leads to failure.


The results of these four abnormalities lead to pumping more poor-oxygen blood to the body and pumping less blood to the lungs, failing the body to acquire enough oxygen. Some factors tend to increase the risk of tetralogy of Fallot, such as:


  • A viral infection during pregnancy, like rubella (measles)
  • Alcohol abuse during pregnancy
  • Malnutrition
  • Pregnancy after 40 years old
  • Family history in the previous generation
  • Down syndrome, which is a genetic disorder that results from an extra 21st chromosome.



Unless treated with corrective surgery, the baby may not have a proper growth and development, along with the susceptibility to grave complications such an inflammation caused by bacteria to the inner lining of the heart called infective endocarditis, or blood clots in the brain leading to a stroke. Disability or death in early adulthood may be the result of an untreated tetralogy of Fallot.


Intracardiac repair:

This is the corrective surgery in which the condition is treated in most of the children within their first year of life. The procedure involves placing a patch on the ventricular septal defect to close the hole between the two ventricles along with widening the pulmonary valve and pulmonary arteries, which results in an increased blood flow to the lungs. Upon completion of the procedure, the symptoms are diminished due to oxygen level increase in the blood. In some cases, when babies are born prematurely or their pulmonary arteries are not yet fully developed (hypoplastic), there might be a need for a temporary surgery before the main one. This temporary surgery involves creating a bypass between the aorta and the pulmonary arteries to increase blood flow to the lungs. When the time comes for the intercardiac repair, the bypass is removed.


After the surgery:

Though unlikely, but some complications are possible after intercardiac repair. Some of the most common complications are:
Chronic pulmonary regurgitation: This is when blood flows back to the heart through the pulmonary valve
Irregular heartbeat (arrhythmia), usually treated by medication. In some cases, even after intercardiac repair, blood flow to the lungs may still be obstructed, raising the need to replace the pulmonary valves with artificial ones. Also, there is a slight risk of blood clots, infection and unexpected bleeding.


Ongoing care:

Children who undergo intercardiac repair need periodic checkups to ensure the success of the procedure and detect possible new problems. Reduced physical activity is recommended for children after surgery along with antibiotics during dental procedures as preventive means against endocarditis, which is an inflammation of the lining of the heart; this is especially recommended for those who have replaced their heart valves with artificial prosthetic material valves.


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Consultants Corner

Dr. Samer Al-Jneidy

Dr. Samer Al-Jneidy Pediatrician

Yaser Habrawi , F.R.C.S.Ed

Yaser Habrawi , F.R.C.S.Ed Consultant Ophthalmologist

Dr. Faisal Dibsi

Dr. Faisal Dibsi Specialist of Otolaryngology - Head and Neck Surgery

Dr. Talal Sabouni


Dr. Tahsin Martini

Dr. Tahsin Martini Degree status: M.D. in Ophthalmology

Samir Moussa M.D.

Samir Moussa M.D. ENT Specialist

Dr. Hani Najjar

Dr. Hani Najjar Pediatrics, Neurology

Dr . Dirar Abboud

Dr . Dirar Abboud Hepatologist – Gastroenterologist

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