Tetralogy of Fallot is the most common cyanotic congenital heart disease in children, accounting for about 10% of congenital heart diseases. It is a complex type of congenital heart condition, consisting of four defects: a ventricular septal defect, right ventricular outflow tract obstruction, overriding aorta, and right ventricular hypertrophy. Due to these four malformations, children will experience cyanosis, poor exercise tolerance, and may quickly become fussy or emotionally disturbed with physical activity. This can lead to noticeable worsening of dyspnea and cyanosis. They may also exhibit a preference for squatting, as squatting can decrease the return blood volume to the heart, increase systemic vascular resistance, and temporarily relieve hypoxic symptoms. Other symptoms include clubbing, paroxysmal hypoxia attacks which are more common in infants. These attacks can be triggered by crying, emotional excitement, anemia, infections, etc., and suddenly manifest as paroxysmal breathing difficulties. In severe cases, there can be fainting, convulsions, and even death. Therefore, these clinical manifestations are very serious, making this disease a significantly dangerous condition.