In children who have tetralogy of Fallot, some low-oxygen blood gets pumped throughout the body. At the same time, not enough blood goes to the lungs because the pulmonary valve is narrow. Children with tetralogy of Fallot may have "tet spells" or "blue spells" if the blood going to the lungs is suddenly reduced. During a "tet spell," your child may look bluish or pale. In infants, this may happen when they are crying or feeding. In older children, it may happen when they are exercising.

• If your child is having a "tet spell":
  • Try to comfort them.
  • Bring their knees to their chest.
  • If they are older than 2 years, have them squat down.

Your child:

• had a "tet spell" and recovered
• is irritable and can't be comforted
• has a fever (temperature higher than 100.4°F)
• is not eating or is vomiting

• after a "tet spell," your child looks blue around the lips, tongue, fingernails, or skin; is listless, very tired, or not responding to you