Most murmurs in healthy asymptomatic children are innocent. The key characteristics of an innocent murmur are they are:
- Always – intensity less than 4/6, no radiation, normal peripheral examination, not diastolic
- Usually – intensity less than 3/6, short in duration, single, change with position, musical or vibratory
Most children will have an innocent murmur at some point during childhood and some persist until adolescence.
Detailed antenatal scanning can pick up major heart defects but a normal antenatal ultrasound does not rule out all cardiac defects.
The majority of pathological heart murmurs are picked up in early infancy.