Innocent Murmur

  • A heart 'murmur' is a sound heard by a doctor when listening to the heart with a Stethoscope. It occurs between, or in addition to, the normal 'heart sounds' and results from some turbulence ('eddies') resulting from the flow of blood through, or close to, the heart. Murmurs are sometimes described as "whooshing noises" produced with each heart beat.

    Whilst some murmurs can indicate the presence of a heart abnormality the commonest murmurs are not due to any heart problem at all. These so-called 'Innocent murmurs' are detected in many normal children. They result from minor turbulence in the flow of blood, which occurs in entirely healthy children and even in adults. Such murmurs are often found during a routine examination, either in infancy or later in childhood. They can also be found in adult life.

    Innocent murmurs are often rather louder, and hence more easily detected, during an illness associated with a raised temperature (fever). As the heart works harder when the body temperature is high this makes the turbulence in blood flow increase and the murmur is louder.

    If a doctor detects a heart murmur, during an illness when the child has a temperature, he will often ask to see the child again after an interval (e.g. when the temperature has returned to normal). This makes it easier for him to decide whether the murmur is normal / innocent.

    If a doctor has picked up a murmur and is unsure as to whether it is normal or whether it may be associated with a heart problem he may arrange some tests or ask another doctor to examine the child. Simple, but useful, tests to try to make sure whether the heart is normal include an Xray of the chest to check whether the heart is enlarged or whether there is any evidence of an abnormality in the appearance of the lungs (which can be due to some heart problems) and an electrocardiogram (ECG). This (the ECG) allows the electrical activity of the heart to be examined, which often indicates whether the heart is under any stress or strain, if an abnormality is present.

    Often a Paediatrician will examine the child and may be able to confirm that the murmur is 'innocent', in which case no further checks may be needed. If there is any continuing uncertainty, or if the doctor or the parents are anxious about the issue, then a consultation with a paediatric cardiologist (children's heart specialist) may be helpful.

    An ultrasound examination of the heart (Echocardiogram) may sometimes be organised, if a heart defect is suspected, but is not usually necessary when the murmur is clearly innocent. The echocardiogram (if required) is painless and takes about half an hour. Some younger children will require sedation for this examination to be performed.