Common benign murmurs that occur in around 1/3 of children at some point during childhood, can be associated with an acute infective illness

Examples/Causes:

• Still’s murmur
• Pulmonary flow murmur - older children and adolescents (also pregnant women)
  • low pitched crescendo/decrescendo heard in early-mid systole
  • heard loudest at the left upper sternal border, when supine and in expiration
• Cervical venous hum
  • 2-7 year age group
  • continuous rumbling sound at the sternoclavicular junction
  • louder on the right side - accentuated by turning the head up and away from the side of the murmur
  • the murmur will dissapear by pressing over the jugular vein, also dissapears when child is supine
• carotid bruit
  • at age 2+
  • crescendo/decrescendo, short, midsystolic sound over the carotid arteries
  • not affected by posture, and importantly in children it must be distinguished from aortic or subaortic stenosis that is radiating to the carotid arteries.
• peripheral pulmonary stenosis
  • Heard in infants in the first 6 months of life (common in premature infants)
  • a blowing, high pitched, short mid-systolic sound, often heard best in the axilla or over the lung fields - if heard over precordium it is loudest in the left upper sternal border

PC

The features of innocent murmurs can be summarised by the 6 S's. They do not all need to be present. These are:

• Soft
• Systolic (note: all diastolic murmurs are pathological) - *always a normal second heart sound
• Sensitive (changes with the child's position / alongside respiration)
• Short (not holosystolic)
• Single (no additional sounds)
• Small (localised, non-radiating)

Management

Innocent murmurs can be made more prominent when children have a febrile illness. If a murmur like this is discovered when a child has a febrile illness, the best option is to review the child in a few weeks. This will allow assessment of the murmur to see if it has resolved with the infection, in keeping with an innocent murmur. If the murmur persists, then further investigation (e.g. echocardiogram) could be considered.