Heart murmurs in babies

What are heart murmurs?

The heart normally makes a recognisable sequence of sounds as blood is pumped through its chambers, and the heart valves open and close. Murmurs are abnormal heart sounds that can be heard using a stethoscope or sometimes by just listening to the chest.

Murmurs are very common during childhood and the vast majority are not a sign of disease or anything to worry about.

Symptoms of a heart murmur

There may be no other symptoms - a murmur is generally diagnosed by the sound heard through the stethoscope.

However, if the murmur is due to disease - ie, it isn't harmless or 'innocent' - the child may be cyanosed (blue, especially around the lips), short of breath (especially on feeding), off their feeds, failing to thrive (poor growth) or have frequent chest infections.

Causes of a heart murmur

The majority of heart murmurs are the result of the fast rate at which children's hearts beat or normal variations in the structure of the heart. Some factors, such as fever or excitement, make these innocent murmurs more likely because they increase the speed at which the heart pumps.

However, a heart murmur is also the most common sign of congenital heart defects caused by abnormal development of the heart tissues. This may be atrial or ventricular septal defects - a hole in the heart or an abnormal hole between two heart chambers. Sometimes the connections between vessels from the heart don't close after birth as they should, resulting in patent ductus arteriosus.

Other abnormalities of the heart valves and still rarer problems can also cause a murmur.

Heart murmurs may also be caused by heart failure and infection involving the heart.

Diagnosing a heart murmur

Innocent murmurs usually make characteristic sounds that can be identified with a stethoscope. However, it can be difficult to tell an innocent murmur from a suspicious one. If a child has an unusual murmur but seems well, the doctor may suggest the child comes back for review in a few weeks or months.

Tests including a chest x-ray, electrocardiogram and echocardiogram may be recommended to examine the structure of the heart and check for abnormalities. If heart disease is suspected, more extensive tests may be needed.

Treatment of a heart murmur

Treatment depends on the cause of the murmur. Innocent murmurs need no treatment and the child can lead a normal active life.

Congenital heart disease often requires major cardiac surgery.

Advances in medicine mean we now understand heart murmurs are rarely the ominous sign they were once thought to be. Even children with severe heart defects usually have a good chance of leading a normal life.

Advice and support

• British Heart Foundation
• Heart HelpLine: 0300 330 3311
• Website: www.bhf.org.uk

• HeartLine Association
• Tel: 0330 022 4466
• Website: www.heartline.org.uk

• Children's Heart Federation
• Tel: 0808 808 5000
• Website: www.childrens-heart-fed.org.uk