Infants with Tetralogy of Fallot often exhibit the following symptoms: First, cyanosis, which is most apparent in areas rich in capillaries such as the lips, fingernail beds, and conjunctiva. Cyanosis tends to worsen gradually during crying, emotional distress, or physical exertion. Second, squatting symptoms; infants who cannot walk often prefer to be held by adults in a flexed position of both lower limbs, reducing venous return and easing the cardiac workload. Older children often exhibit squatting during activities such as walking and playing, frequently squatting down momentarily. Third, infants in a prolonged hypoxic environment may develop clubbing, characterized by the enlargement of the fingertips and toes, with capillary expansion and proliferation, resembling drumsticks. Fourth, episodic hypoxia occurs predominantly in infants, triggered by feeding, crying, or emotional distress, manifesting as episodes of respiratory difficulty, with severe cases leading to sudden fainting or convulsions.