Overview
Heart murmurs are common in asymptomatic and healthy children and may be innocent. However, murmurs may be the only initial sign of congenital heart disease (CHD).
Features
Innocent murmurs
Also known as functional murmurs, these are murmurs that occur due to normal physiological blood flow through the heart and blood vessels. Features suggesting an innocent murmur can be remembered using the seven S’s:
- Sensitive – changes with the child’s position or with respiration
- For example, a murmur heard when supine may disappear when sitting upright
- Short – not pansystolic
- Single – no associated clicks/gallops
- Small – non-radiating and limited to a small area
- Soft – low amplitude
- Sweet – not harsh sounding
- Systolic – only happens in systole
Other features supporting an innocent murmur include:
- An asymptomatic child
- No other abnormalities
- No thrills
Pathological murmurs
Features suggesting pathological murmurs are opposites of the above:
- Not systolic: diastolic murmurs – all diastolic murmurs are pathological
- Not short: pansystolic murmurs
- Not sweet: harsh murmurs
- Not single: additional abnormal heart sounds and clicks
- Not soft – grade 3 murmur or greater
- Heard over the upper left sternal border
Differential Diagnoses
Innocent murmurs
Innocent murmurs include:
- Still’s murmur:
- Location: lower left sternal edge mid-systolic murmur
- Sound: musical/vibratory sound
- Differential(s): ventricular septal defects
- Venous hum:
- Location: under the right/left clavicles
- Sound: only heard in upright position, blowing noise
- Differential(s): pulmonary stenosis, atrial septal defect
- Pulmonary ejection murmur:
- Location:
- Sound(s):
- Differential:
- Not single: additional abnormal heart sounds and clicks
- Not soft – grade 3 murmur or greater
- Heard over the upper left sternal border
Differential Diagnoses
Innocent murmurs
Innocent murmurs include:
- Still’s murmur:
- Location: lower left sternal edge mid-systolic murmur
- Sound: musical/vibratory sound
- Differential(s): ventricular septal defects
- Venous hum:
- Location: under the right/left clavicles
- Sound: only heard in upright position, blowing noise
- Differential(s): pulmonary stenosis, atrial septal defect
- Pulmonary ejection murmur:
- Location: upper left sternal border
- Sound(s): mid-systolic
- Differential: pulmonary stenosis, atrial septal defect
Pathological murmurs
Pathological murmurs include:
- Ventricular septal defects (VSDs):
- Pansystolic murmur in the left parasternal region, which may be harsh
- Smaller VSDs tend to cause louder murmurs
- Atrial septal defects:
- Ejection systolic murmur with fixed splitting of the second heart sound
- ‘Fixed splitting’ means the second heart sound does not become a single heart sound with expiration
- May become louder with inspiration
- Patent ductus arteriosus:
- A continuous ‘machinery’ murmur below the clavicle that may radiate to the back
- Ebstein’s anomaly:
- May be associated with tricuspid regurgitation which is heard as a pansystolic murmur at the lower left sternal edge
Investigations
Overview
If a clinical diagnosis of an innocent murmur cannot be made (e.g. the murmur sounds similar to a pathological one), then an echocardiogram should be performed.
