Heart murmurs
Heart murmurs can be a cause of great anxiety, particularly to the parents of children in whom a murmur has been noticed.
But up to a quarter of people may have a heart murmur at one time or another and they are even more common in young children.
The heart is listened to through an instrument called a stethoscope — an instrument which amplifies the sounds made with each heartbeat. Murmurs are heard between heartbeats if the stream of blood flowing into, out of, and through the heart, becomes turbulent. This can be likened to the way the water in a smooth flowing river will 'break up' if a rock or other object is in its path.
Many things will cause the stream of blood to become turbulent. Sometimes it happens when there is increased blood flow due to a faster heart rate during exercise, or in pregnancy. Because young children have much faster heart rates than adults, many of them will have one of these harmless ‘flow’ murmurs. With normal ageing there may be some narrowing of the blood vessels taking blood to and from the heart, and the blood — having to pass through a narrower channel — may not flow as smoothly as before, producing a murmur.
Newborn children whose hearts have not formed correctly (congenital heart disease) will usually have a murmur. While some forms of congenital heart disease may be relatively minor and may resolve spontaneously, other forms may be extremely serious and require major corrective surgery.
A relatively common cause of significant heart murmurs in adults is damage to one or more of the valves in the heart. The heart has 4 separate chambers, a left and right ventricle and left and right atrium. Valves are present between the atrium and ventricle on each side and also at the places where blood leaves the heart — the aorta and the pulmonary artery. These valves are essential for the heart to function normally and to be able to send blood to the right place at the right time. When valves are damaged they may become too ‘tight’ (a condition referred to as stenosis) or too loose, allowing blood to flow back through them in the wrong direction. This is known as incompetence. Fortunately it is often possible to repair or even replace these damaged valves, returning the heart to normal function.
When a heart murmur is noticed and is not obviously ‘innocent’ a number of tests may be needed to find its cause. One of these is an echocardiogram which uses sound waves to build a picture of the blood flowing through the heart, allowing the doctor to see where the turbulence is happening.
If the doctor notices that you or your child has a heart murmur there is a good chance it is quite harmless, especially if you are physically well. If they are uncertain whether or not it is an ‘innocent murmur’, they will investigate further or refer you to a specialist. If an important cause is found, treatment is usually possible.
Last Reviewed: 13 February 2009
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