Generally speaking, murmurs occur when the blood flows too quickly or with too much force between the parts of the heart, causing the walls of the heart or large blood vessels to vibrate. In addition, if the normal channels between parts of the heart become too narrow, or if there are abnormal channels in the heart, abnormal “vortices” can be created as the blood flows through them, and a murmur can occur. In some children, a heart murmur can be heard but there is no heart disease. It is thought that the murmur occurs because the normal vibration is enhanced by the blood flow in the pediatric pulmonary artery. The murmur is variable, sometimes very mild, sometimes more pronounced, and sometimes even absent. It is usually more pronounced after a child has a fever, cries, exercises vigorously or lies flat, and diminishes after the fever has subsided, when quiet or after sitting up. So a murmur in a child’s heart does not necessarily mean heart disease, and it does not necessarily mean congenital heart disease. When a child is found to have a heart murmur, first of all, all aspects of the examination should be carried out, if the diagnosis is not clear for a while, whether or not congenital heart disease, parents should not be nervous, should be regularly re-examined. There are also some congenital heart disease without murmur, so this alone should not negate the diagnosis of congenital heart disease. As for the loudness and pitch of the murmur is also different, some congenital heart disease abnormal channel is very small, the blood flow through it will appear high tone louder murmur; while some other abnormal channel caliber is larger, blood flow through the murmur but the tone is lower and lighter. Obviously, the larger the abnormal channel mouth, the more serious the lesion. Therefore, the severity of the disease cannot be judged only by the loudness and pitch of the murmur.