The severity of congenital heart disease varies greatly, mainly due to the structural abnormalities of the heart that cause functional differences, and the degree of impact on function and compensatory capacity determines the severity of the condition. Which disease is serious? The severity of the disease varies from one disease to another, and even for the same disease, the severity can vary greatly. For a specific patient, the severity of the disease may be different at different times. For example, in the simplest form of congenital pulmonary stenosis, if the stenosis is not severe, the child may survive to an older age without symptoms, whereas in some cases, because of severe stenosis and no other shunt, the child will die shortly after birth. Therefore, congenital heart disease cannot be considered as simple or complex preconditioning, but depends on its impact on the patient’s physiology. Simple congenital heart disease can become serious or lost if not treated promptly. There are some complex congenital heart diseases that, due to their special anatomy, may have little effect on the circulatory system temporarily.