The clinical manifestations of Tetralogy of Fallot include cyanosis, with cyanosis being the primary symptom. The severity of cyanosis is related to the extent of pulmonary stenosis and is commonly seen in areas rich in capillaries, such as the lips, fingertips, nail beds, and conjunctiva, where it appears more pronounced during physical activity or crying. Secondly, the squatting symptom is observed; children may show squatting behavior during walking or playing, often squatting down voluntarily for a moment. During squatting, the flexion of the lower limbs reduces the venous return to the heart, lightening the cardiac load and decreasing the right-to-left shunting, thereby alleviating hypoxia. Thirdly, clubbing of the fingers occurs due to long-term hypoxia, leading to hypertrophic growth at the fingertip and toe ends. Fourthly, paroxysmal hypoxic attacks occur.