Tetralogy of Fallot correction (TOF correction) is a surgical procedure used to fix several congenital heart defects (present at birth). These defects affect the structure of the heart and cause oxygen-poor blood to flow out of the heart and to the rest of the body. When oxygen-poor blood is pumped to the body, the fingers, toes, and lips may appear blue. This condition is called cyanosis. Other symptoms may include shortness of breath and rapid breathing, clubbing of fingers and toes (thickening of the nail bed, causing the nail to curve downward), poor weight gain, and irritability. It is often diagnosed during infancy or soon after. Repairing the defects can greatly improve the child’s health and quality of life.