These defects, which affect the structure of the heart, cause the heart to pump blood with insufficient oxygen to the rest of the body. In general, infants and children with tetralogy of Fallot have bluish skin because the blood does not carry enough oxygen.

Tetralogy of Fallot is often diagnosed during the first year of life or immediately thereafter. However, tetralogy of Fallot may only be detected later in life in some adults, depending on the severity of the defects and symptoms.

With early diagnosis and appropriate surgical treatment, most children and adults with tetralogy of Fallot can lead a relatively normal life, although they will need regular medical care throughout their lives and may need to restrict physical activity.