Tetralogy of Fallot (TOF) is a type of heart defect present at birth. Symptoms at birth may vary from none to severe. Later, there are typically episodes of bluish color to the skin known as cyanosis. When affected babies cry or have a bowel movement, they may develop a "tet spell" where they turn very blue, have difficulty breathing, become limp, and occasionally lose consciousness. Other symptoms may include a heart murmur, finger clubbing, and easy tiring upon breastfeeding.
The cause is typically not known. Risk factors include a mother who uses alcohol, has diabetes, is over the age of 40, or gets rubella during pregnancy. It may also be associated with Down syndrome. Classically there are four defects:pulmonary stenosis, narrowing of the exit from the right ventricle a ventricular septal defect, a hole between the two ventricles right ventricular hypertrophy, thickening of the right ventricular muscle an overriding aorta, which allows blood from both ventricles to enter the aorta
TOF is typically treated by open heart surgery in the first year of life. The timing of surgery depends on the baby's symptoms and size. The procedure involves increasing the size of the pulmonary valve and pulmonary arteries and repairing the ventricular septal defect. In babies who are too small, a temporary surgery may be done with plans for a second surgery when the baby is bigger. With proper care, most people who are affected live to be adults. Long-term problems may include an irregular heart rate and pulmonary regurgitation.
TOF occurs in about 1 in 2,000 newborns. Males and females are affected equally. It is the most common complex congenital heart defect, accounting for about 10 percent of cases. It was initially described in 1671 by Niels Stensen. A further description was published in 1888 by the French physician Étienne-Louis Arthur Fallot, after whom it is named. The first total surgical repair was carried out in 1954.