Tetralogy of Fallot (TOF), formerly known as Steno-Fallot tetralogy, is a congenital heart defect characterized by four specific cardiac defects. Classically, the four defects are: Pulmonary stenosis, which is narrowing of the exit from the right ventricle; A ventricular septal defect, which is a hole allowing blood to flow between the two ventricles; Right ventricular hypertrophy, which is thickening of the right ventricular muscle; and an overriding aorta, which is where the aorta expands to allow blood from both ventricles to enter. At birth, children may be asymptomatic or present with many severe symptoms...