This page explains how doctors distinguish between innocent and serious heart murmurs.
Murmurs are sounds the heart makes. The sound is made by the movement of the blood through the heart. A regular heartbeat makes a “lub-dub” sound. When there is a murmur, a “swooshing,” almost vibrating sound can be heard in addition to the “lub-dub.” A doctor hears the sound through a stethoscope placed on the chest. The type of sound the heart makes will help the doctor determine whether there is a problem or not, and if there is, what kind of problem.
Heart murmurs are quite common in children, occurring in about one in every two children. In fact, it is possible to hear a murmur in just about all children at some time or another in their young lives. It is more common to hear a murmur when a child is excited or has a fever.
Most murmurs are normal. Only about one in 100 murmurs indicates a problem with the heart.
Heart murmurs are rated on a scale from 1 to 6. Grade 1 means it can barely be heard, while grade 6 means it is very loud.
What are innocent murmurs?
Innocent murmurs don’t cause problems for a child and do not require treatment. They are also called functional, physiological or benign murmurs, or flow murmurs because they reflect the sound of regular blood flow.
Innocent murmurs can usually be heard when the child is between the ages of two and six. At this age, they are simply easier to hear than they were when the child was younger.
If a child is found to have an innocent murmur, it means they are healthy and do not need any treatment or activity restrictions. A heart murmur is also no indication that a child will have heart disease later in life.
The most common innocent murmur is Still’s murmur. Other murmurs include benign pulmonary outflow murmur, carotid bruit, and venous hum.
How does the doctor determine whether a murmur is innocent?
By listening to your child’s heart, the doctor will check to see where the heart murmur can be heard within the heart, the type of noise it makes (for example, clicking or blowing), whether it changes when the child moves, and when it occurs in the heartbeat process. Often the doctor will be able to tell just by listening whether it needs to be examined further.
What might indicate a serious murmur?
A doctor would be concerned about a murmur if it was accompanied by other symptoms. These might include cyanosis and breathing or eating difficulties. If an X-ray showed an enlarged heart, or other abnormal results, your family doctor or paediatrician would arrange for an echocardiogram or an electrocardiogram. If there is a heart problem, your child would be referred to a paediatric cardiologist.
What causes serious murmurs?
Serious murmurs are generally caused by heart defects, like heart valves that aren’t working properly or holes in the walls of the heart.
How are murmurs treated?
Once the doctor has done some tests, they will make a diagnosis and share it with you. If the murmur is innocent, no treatment will be needed. If the murmur is an indication of a more serious problem, the doctor will discuss the nature of the problem and the treatment options with you.