heart murmur
Meaning of heart murmur: Most murmurs are harmless noise from normal blood flow, which is why the character of the sound matters more than its presence.
Definition of heart murmur
A heart murmur is an extra sound heard through a stethoscope as blood moves through the heart, produced when flow becomes turbulent instead of smooth. It may arise from a narrowed or leaking valve, a hole between two chambers, or simply from blood moving quickly through a normal heart. The sound itself is a finding, not a diagnosis.
What makes the sound?
Blood moving smoothly through a healthy heart is almost silent, and a stethoscope picks up little more than the brief clicks of the valves closing. Turbulence changes that. When blood is forced through an opening that is too narrow, leaks backward through a valve that no longer seals, or crosses a hole between two chambers, the flow breaks into eddies that set the surrounding tissue vibrating. That vibration is audible as a whoosh, rumble or blowing sound filling part of the beat. Speed matters as much as structure, so fever, anemia, pregnancy and exercise can all make a structurally normal heart audible.
Which murmurs are harmless?
A great many. A murmur with no underlying abnormality is called innocent or functional, and it is common in children, in pregnancy and in anyone with a fast circulation. Innocent murmurs tend to be soft, short, confined to the contraction phase and unaccompanied by any other finding. The features that draw attention are the opposite ones, and they are what the listener is sorting for.
| Feature | Usually innocent | Needs explanation |
|---|---|---|
| Timing | Brief, early, during contraction | Fills the beat, or falls in the relaxation phase |
| Loudness | Soft, and varies with position | Loud or harsh, sometimes felt as a buzz through the hand |
| Company | No other symptoms or signs | Breathlessness, fainting, chest pain, poor growth in a baby |
| Spread | Stays near the breastbone | Carries into the neck or the armpit |
How is the cause worked out?
Listening places the murmur within the cycle and locates where it is loudest, which narrows the possibilities considerably before any test is arranged. The step that settles it is echocardiography, an ultrasound scan that watches each valve open and close and measures the direction and speed of flow across it. Narrowing of the aortic valve, leaking of the mitral valve and holes between chambers each produce a recognizable pattern. Where a valve fault has strained the heart for long enough, the signs of congestive heart failure appear alongside the sound, and the murmur is then the audible edge of a larger problem.
Also known as
Used in a sentence
A soft systolic murmur was audible at the left sternal border.
Good to know
A murmur names a sound rather than a disease, and its timing, loudness, location and spread carry the information; the commonest murmurs in children and in pregnancy come from increased flow through structurally normal hearts.
Word origin
Where “heart murmur” comes from
Murmur comes directly from the Latin murmur, meaning a humming, rumbling or muttering sound.