Everything You Need to Know About Tetralogy of Fallot

Everything You Need To Know About Tetralogy Of Fallot

What is tetralogy of Fallot?

Tetralogy of Fallot is a rare congenital heart defect that is characterized by a combination of four different heart defects. The heart is a muscular organ that is about the size of a fist. It is on the left side of the chest region. It is made up of four chambers:

  • The right atrium: which will receive deoxygenated blood from the three major veins and a few smaller veins. It pumps blood into the right ventricle through the help of the tricuspid valve. The major veins are superior vena cava, inferior vena cava, and the coronary sinus. The smaller veins are anterior cardiac veins and the smallest cardiac veins. 
  • The right ventricle: It receives deoxygenated blood from the right atrium through the help of the tricuspid valve. The blood in the right ventricle is carried to the lungs by the pulmonary artery, where it is loaded with oxygen. The valve that controls the blood flow between the right ventricle and the pulmonary artery is the pulmonary valve. 
  • The left atrium: It receives oxygenated blood from the lungs through pulmonary veins. It is then pumped to the left ventricle through the help of the mitral valve. 
  • The left ventricle: This is the strongest chamber of the heart. It pumps oxygen-rich blood to all the rest of the body through the help of the aorta. The valve that controls blood flow is the aortic valve. 

In the tetralogy of Fallot, the structures of the heart involved are the ventricles, aorta, and pulmonary valve. These structures can be affected individually as a single condition or together as in the tetralogy of Fallot. 

What are the four defects of tetralogy of Fallot?

The four conditions that make up the tetralogy of Fallot are:

  1. Pulmonary valve stenosis:  It is the narrowing of the pulmonary valve. This leads to backflow of deoxygenated blood(low oxygen blood) into the right ventricle, the right atrium, and decrease the amount of blood flowing into the lungs. 
  2. Ventricular septal defect:  It is is a hole (defect) in the wall (septum) that separates the left and right ventricles. This allows deoxygenated blood in the right ventricle to flow into the left ventricle and oxygenated blood to flow into the right ventricle. Over time, this back and forth weakens the heart’s ability to pump effectively due to the heart’s attempt to compensate the body for the less oxygen it receives.
  3. Right ventricular hypertrophy: The backflow of blood into the right ventricle cause the ventricle to work more. The more it works, the thicker the heart muscle becomes. Over time the muscle becomes weak and fails. 
  4. Overriding aorta: It is the shifting of the aorta to the right and directly above the ventricular septal defect. This leads to the flow of deoxygenated and oxygenated from both ventricles into the aorta. 

Tetralogy of Fallot causes blood with less oxygen to flow out of the heart and into the body. This leads to several health discomforts. 

Symptoms Of Tetralogy Of Fallot

Here are the sign and symptoms Of Tetralogy Of Fallot:

  • Tet spell: is the sudden development of difficulty in breathing, loss of consciousness that occasionally occurs, bluish discoloration of the skin, nails and lips of a baby with Tetralogy Of Fallot when he or she cries, eat, or is agitated.
  • Cyanosis of skin (blue-tinged skin)
  • Finger clubbing and toes (abnormal, rounded shape of the nail) 
  • Rapid breathing
  • Failure to thrive (difficulty gaining weight)
  • Prolonged crying in infants
  • Mild activities lead to physical exertion (extreme tiredness).
  • Irritability
  • Heart murmurs

What is the most common cause of congenital heart defects?

There is no specific known cause for congenital heart defects, but certain factors increase the odds of a child being born with a heart defect:

  • A maternal viral illness, such as rubella (German measles).
  • Maternal diabetes
  • Down syndrome
  • Maternal alcoholism
  • Family history of congenital heart defects

How is tetralogy of Fallot diagnosed?

  • Echocardiogram: establishes the presence of TOF by demonstrating a ventricular septal defect, right ventricular hypertrophy, and aortic override.
  • Chest X-ray: will show the abnormal “coeur-en-sabot” (boot-like) appearance of the heart with the absence of interstitial lung markings. 
  • Electrocardiography: presence of right ventricular hypertrophy (RVH) with right axis deviation.
  • Pulse oximetry: measures oxygen saturation. 
  • Cardiac catheterization. 

Treatment Of Tetralogy Of Fallot


  • Open heart surgery: is usually done in the first year of life to repair the damage. 
  • Palliative surgery is an option that is usually carried out to correct the heart before open-heart surgery. 

Other treatment options include:

  • Beta-blockers (propranolol). 
  • Morphine. 
  • Intranasal fentanyl. 
  • Phenylephrine. 
  • Oxygen therapy. 


  • Squatting increases blood flow to the lungs. Therefore, Squatting during a Tet spell is recommended. 
  • Placing the baby on his or her side and pulling your baby’s knees up to his or her chest when he or she becomes blue is a good way to bring relief to your child.