If you have a harmless heart murmur, more commonly known as an innocent heart murmur, you likely won't have any other signs or symptoms. An abnormal heart murmur may cause no obvious other signs or symptoms, aside from the unusual sound your doctor hears when listening to your heart with a stethoscope. But if you have these signs or symptoms, they may indicate a heart problem: Skin that appears blue, especially on your fingertips and lips.
http://www.mayoclinic.org/diseases-conditions/heart-murmurs/basics/symptoms/CON-20028706
An innocent murmur does not cause any symptoms. For other types of heart murmurs, symptoms vary depending on the cause. In general, when a heart murmur significantly interferes with the heart's ability to pump blood, you can experience one or more of the following symptoms: Shortness of breath.
https://www.drugs.com/health-guide/heart-murmur.html
Overview of Heart Murmur. A heart murmur is an abnormal whooshing or swishing sound heard with a stethoscope when there is unsteady blood flow near the heart. This sound is different from the usual lub-dub heartbeat sound. Heart murmurs can be loud or soft.
http://www.healthcommunities.com/heart-murmur/heart-murmur-overview.shtml
Parents might worry if they're told that their child has a heart murmur. But heart murmurs are very common, and many kids are found to have one at some point. Most murmurs are not a cause for concern and won't affect a child's health at all. The term heart murmur isn't a diagnosis of an illness or disorder. To better understand what it does mean, it helps to know a bit about the heart.
http://kidshealth.org/en/parents/murmurs.html
A heart murmur is a sound. It is not a disease or necessarily a problem. I often tell families it’s a sound that tells us to listen and evaluate carefully to see if there is something wrong. Murmurs are typically the sound of blood crossing a valve or other structure in the heart or blood vessels.
http://childrens.memorialhermann.org/patients-families/understanding-childrens-heart-murmurs/
A heart murmur isn't a disease — but murmurs may indicate an underlying heart problem. Often, heart murmurs are harmless (innocent) and don't need treatment. Some heart murmurs may require follow-up tests to be sure the murmur isn't caused by a serious underlying heart condition. Treatment, if needed, is directed at the cause of your heart murmur. Symptoms.
http://www.mayoclinic.org/diseases-conditions/heart-murmurs/basics/definition/CON-20028706
Patients with innocent murmurs have healthy, normal hearts and usually do not need treatment. Innocent heart murmurs frequently are detected in children. Innocent heart murmurs may become louder or softer when the heart rate changes from exercise, excitement, or anxiety; however, this usually is not cause for concern.
http://www.healthcommunities.com/heart-murmur/heart-murmur-overview.shtml
A hole in the heart is a common cause of abnormal murmurs in children. Cardiac shunts occur when blood flows abnormally through holes in the heart chambers or through the pulmonary and aortic valves. Valve calcification is hardening or thickening of valves that occurs with age.
http://childrens.memorialhermann.org/patients-families/understanding-childrens-heart-murmurs/
Innocent heart murmurs are often due to rapid blood flow through the heart, which can be caused by: 1  Strenuous exercise or physical activity. 2  Excitement or fear. 3  Fever. Anemia.  Variations in artery size and angles as the child grows.
http://childrens.memorialhermann.org/patients-families/understanding-childrens-heart-murmurs/
A heart murmur is a sound made by turbulent blood flow within the heart. Your doctor hears this sound with a stethoscope. A murmur can occur in a normal heart. Or it may indicate some problem within the heart. Most often, the turbulence is normal. And the sound is called a benign flow murmur.
https://www.drugs.com/health-guide/heart-murmur.html
what do heart murmurs come from
Heart murmurs come from turbulent blood flow within the heart.