Heart murmurs can be either innocent or abnormal, with abnormal heart murmurs indicating a serious heart condition such as damaged heart valves

A normal heartbeat has two sounds. A heart murmur is the extra rasping, humming or whooshing sound that can be heard in-between. It must be investigated to be sure it’s “innocent”, meaning harmless.

As opposed to an innocent heart murmur, an abnormal heart murmur may point to a serious underlying heart problem such as damaged heart valves or congenital heart defects like a hole in the heart.

“Prognosis for abnormal heart murmurs varies according to the underlying heart problem and its severity. It is excellent in patients with otherwise structurally normal hearts and poor in patients with severe underlying valvular or congenital heart defects,” say ​doctors from the ​Department of Cardiology, National Heart Centre Singapore (NHCS), a member of the SingHealth​ group.

Innocent heart murmurs

Innocent heart murmurs are common​ in children. “About 50 per cent of children will have a heart murmur detected during a routine physical examination at some point in their childhood, but only less than 1 per cent are abnormal heart murmurs,” say​ doctors.​

In adults, an innocent heart murmur may be triggered by:

1. Pregnancy
2. Physical exercise
3. Fever
4. Anaemia (low red blood cell count)
5. Hyperthyroidism (overactive thyroid)

Because patients with innocent heart murmurs have structurally normal hearts and no underlying heart problems, these murmurs may disappear over time, or they may persist without causing any harm.

Abnormal heart murmurs

Abnormal heart murmurs in children are usually due to congenital heart defects such as a hole in the heart, abnormalities in the heart chambers or their connecting blood vessels, or defective heart valves. For instance, the heart valves can be too thick and narrow (valve stenosis) to allow normal blood flow, or they can leak (valve regurgitation).

These congenital heart problems put undue pressure on the heart which must work harder to pump the required amount of blood, resulting in turbulent blood flow - and heart murmurs.

Abnormal heart murmurs in adults are often the result of acquired heart valve diseases such as damaged heart valves due to ageing, rheumatic fever, valve stenosis, ischaemic heart disease and endocarditis (infection of the endocardium, the heart’s inner lining).

6 tips to prevent abnormal heart murmurs

You can effectively reduce your risk of developing an abnormal heart murmur by following these six tips:

1. Eat a healthy diet.
2. Exercise regularly.
3. Quit smoking.
4. Cut down on alco​​hol.
5. Keep pre-existing illnesses, such as high blood pressure, diabetes or high cholesterol, under control.
6. Maintain good dental hygiene to prevent bacteria from potentially getting into the bloodstream and affecting the heart valves.​

See previous page for the causes, symptoms and t​reatments for heart murmurs​.

Ref: S13​