Heart murmurs are additional sounds a doctor might hear when listening to the beat of a heart with a stethoscope. They are sometimes called extra beats. They often have a rushing or whooshing sound, though other sounds can indicate that heart murmurs have a specific cause.
Frequently, heart murmurs heard in children are completely innocent. They may be heard a few days after birth, and often are the result of the ductus, a small opening between the left and right arteries above the heart, remaining open. A murmur due to an open ductus usually disappears within a few weeks. In preemies, the ductus may remain open and require closure at a later date. Unless the ductus is causing significant problems for the newborn, closure is usually not attempted for six months to a year.

Heart murmurs may arise in the first few days of life from the change in circulation. When a child is born, the body begins to circulate blood in the opposite direction. This new form of circulation may cause an initial murmur that disappears shortly after birth.
Tiny differences in heart formation may also result in heart murmurs. These can be heard in children from birth, or when children are around two. Usually such heart murmurs are innocent and tend to disappear within a few years. Innocent heart murmurs are often referred to as functional heart murmurs.
Heart murmurs are graded on their sound. The quietest murmurs receive a grade one. The loudest heart murmurs are rated as grade six. It is not unusual for even functional murmurs to be somewhat loud, and receive a grade between three and six.
In adults, heart murmurs can also be functional. People who suffer from anxiety may sometimes have additional beats called pre-atrial contractions or pre-ventricular contractions. These heart murmurs are quite normal and do not represent danger to the heart.
While most heart murmurs are functional, some can indicate serious illness or problems with the heart. Often children with congenital heart defects will have heart murmurs. Usually, heart murmurs are accompanied by other classic symptoms such as poor growth, blue tinge to the skin, failure to thrive, inability to eat, or breathing difficulties. These murmurs are a cause for concern, and one should take these concerns to a pediatric cardiologist, who can diagnose specific heart defects and determine treatment.

Heart murmurs that are present in teenagers and young adults, and have a honking or clicking sound, may indicate a defect called mitral valve prolapse. The symptoms of this defect usually are not present when a child is young. Mitral valve prolapse, a defect of the valve between the left atrium and left ventricle, usually requires treatment or replacement of the valve. Often the honking sound can be heard without a stethoscope, and should immediately be brought to the attention of a physician.