Tetralogy of Fallot is a complex congenital heart disease, characterized by ventricular septal defect, right ventricular outflow tract obstruction, aorta overriding, and right ventricular hypertrophy. When the obstruction of the right ventricular outflow tract is severe, pulmonary artery blood flow significantly decreases. A large amount of unoxygenated venous blood passes through the ventricular septal defect causing a right-to-left shunt, which clinically manifests as severe cyanosis and increased red blood cells, and different degrees of hypoxia in the systemic circulation. Factors that can induce hypoxic episodes in these infants include feeding, crying, emotional agitation, anemia, infection, etc. These can suddenly lead to fainting, convulsions, or even death. The main reason is generally due to a sudden muscle spasm at the narrow pulmonary artery infundibulum on top of pre-existing stenosis, causing temporary pulmonary artery obstruction and exacerbating cerebral hypoxia, thus leading to severe hypoxic attacks.