1.Cyanosis is an important symptom of complex congenital heart disease, manifested in skin and mucous membrane cyanosis, especially intensified after crying and noise and activity, such as cyanosis in neonatal period, common ones are complete aortic dislocation, pulmonary atresia, etc.; after 6 months, cyanosis gradually appears in tetralogy of Fallot, etc. 2. Squatting is a common manifestation of tetralogy of Fallot. When the child can walk, you will find that he does not move much and feels weak after walking a short distance, so he will automatically adopt a squatting position or take a chest and knee position, and then stand up again after resting for a moment. The episodes of hypoxia often occur during nursing, crying and defecation. Sudden onset of respiratory distress, cyanosis, unconsciousness and even coma, cramps 4, long-term hypoxia leads to soft tissue hyperplasia at the end of the fingers (toes), resulting in drumstick-like changes in the fingers and toes, called pestle-like fingers (toes), which often appear clinically after 2 to 3 years of age 5, long-term hypoxia can cause the formation of a large number of collateral blood vessels in the lungs, and the rupture of blood vessels can cause hemoptysis when coughing violently.