What are the symptoms of Tetralogy of Fallot?

By  ,  National Institute of Health
Jan 06, 2013

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An important sign of tetralogy of Fallot is cyanosis.


Cyanosis is a bluish tint to the skin, lips, and fingernails. Low levels of oxygen in the blood cause cyanosis.

Babies who have unrepaired tetralogy of Fallot sometimes have “tet spells" in response to an activity like crying or having a bowel movement. A tet spell occurs when the oxygen level in the blood suddenly drops. This causes the baby to become very blue. The baby also may:

  • Have a hard time breathing
  • Become very tired and limp
  • Not respond to a parent's voice or touch
  • Become very fussy
  • Lose consciousness

In years past, when tetralogy of Fallot wasn't treated in infancy, children would get very tired during exercise and could faint. This heart defect is now repaired in infancy to prevent symptoms like this.

Another common sign of tetralogy of Fallot is a heart murmur.


A heart murmur is an extra or unusual sound that doctors may hear while listening to the heart.

The sound occurs because the heart defect causes abnormal blood flow through the heart. However, not all heart murmurs are signs of congenital heart defects. Many healthy children have heart murmurs.

Normal growth and development depend on a normal workload for the heart and normal flow of oxygen-rich blood to all parts of the body. Babies who have tetralogy of Fallot may not gain weight or grow as quickly as children who have healthy hearts because they tire easily while feeding.

Children who have tetralogy of Fallot also may have clubbing. Clubbing is the widening or rounding of the skin or bone around the tips of the fingers.



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