Clinically, congenital heart disease is generally classified into three major categories according to the presence or absence of shunts between the left and right sides of the heart and large blood vessels. 1.left-to-right shunt lesions (latent cyanosis) Under normal conditions, blood is shunted from left to right because the pressure of body circulation is higher than that of pulmonary circulation, so cyanosis does not appear. When the pressure in the pulmonary artery or right ventricle is increased and exceeds the pressure in the left heart due to severe crying, breath-holding or any pathological condition, the blood may be shunted from right to left and temporary cyanosis may occur, such as ventricular septal defect, patent ductus arteriosus, atrial septal defect, endocardial cushion defect and partial ectopic pulmonary venous drainage. This type of preconditioning is prone to pneumonia and pulmonary hypertension, among which perimembranous and myocardial ventricular septal defects, patent ductus arteriosus and secondary foramen ovale septal defects can be treated with intervention. 2, right-to-left shunt lesions (cyanosis) Some reasons (such as right ventricular outflow tract stenosis) cause the right heart pressure to increase and exceed the left heart, so that the blood flow from the right to the left shunt, or due to the abnormal origin of the large arteries, so that a large amount of venous blood flow human circulation, can be out of persistent cyanosis, such as Farrow’s tetralogy and transposition of the great arteries. This kind of precordial disease is easy to die, need early diagnosis and timely surgical treatment. 3, no shunt type (obstructive lesions) (no cyanosis type) that is, there is no abnormal access or shunt between the left and right sides of the heart or large vessels, such as pulmonary stenosis, aortic stenosis and aortic constriction. Pulmonary stenosis can be cured by interventional surgery, while the latter two require surgical treatment to relieve the obstruction.