Heart murmur: what is it, what causes it and most importantly... do we need a cure?

By Cristiano Antonino Last updated Jun 16, 2023

A heart murmur is a condition in which the blood generates a noise of a duration, intensity and frequency that is different from the physiological one

The blood, passing through the heart does not generate any noise; the heart murmur may sometimes be inaudible, at other times it is audible and by using the phonendoscope this ‘murmur’ is accentuated.

The noise is due to the valve constricting, which prevents normal blood flow and if it cannot hold it back, there will be some sort of reflux which will generate noise.

Generally, a heart murmur is not associated with serious diseases, but it may hide some.

Types of heart murmurs

A heart murmur, which is common in children, is physiological but is linked neither to problems nor to cardiac malformations, and in most cases tends to disappear with time.

An abnormal heart murmur, on the other hand, appears as a result of pathologies or congenital malformations.

It occurs in children and adults.

An abnormal murmur indicates a more serious heart problem.

In children they are caused by a congenital heart disease; in adults they are linked to reduced function of the heart valves, a condition that develops with age.

Systolic murmur, will make noises during ventricular systole, i.e. when the heart contracts and carries blood to the ventricles via the atrioventricular and semilunar valves.

It is caused by insufficiency of the former or narrowing of the latter.

The diastolic murmur, will give rise to murmurs that will be audible in the ventricular phase, thus when the heart relaxes releasing blood from the ventricles.

It is due to the narrowing of the atrioventricular valves or the inefficiency of the semilunar valves.

Continuous murmurs will be heard in the systolic and diastolic ventricular phase.

They will occur in the presence of congenital heart disease. However, the murmurs will vary in duration, intensity and perceived noise.

What are the causes of heart murmurs?

Innocent heart murmurs will occur when the circulation of blood in the heart is faster than normal.

This can be a consequence of: physical activity, pregnancy, fever, anaemia, hyperthyroidism, rapid growth in adolescence.

Abnormal heart murmurs will be congenital in children as a consequence of a heart defect present from birth.

Congenital defects that cause heart murmurs are

Holes or deviations of blood flow in the heart muscle; depending on size and position, they can be mild or severe. Blood flow deviations occur when the passage of blood between atria/ventricles or between blood vessels is abnormal.
Heart valve abnormalities; the valve, due to its narrowing, will not allow proper blood passage or blood will flow back due to the valve not closing.
These abnormalities are usually present from birth but are sometimes diagnosed in the first years of life.
Other causes of abnormal heart murmurs can be infections and other conditions that damage the structures of the heart; they are more common in older children and adults:
Valve calcification, as we age, the valves can harden or thicken and narrow making it more difficult for blood to pass through: the vortex caused by the slowing of flow is the cause of the heart murmur.
Endocarditis, an infection of the inner lining of the heart and valves, occurs when bacteria spread through the blood and reach the heart. The infection, left untreated, causes significant damage to the heart valves.
Rheumatic fever, is a serious condition that can occur following a streptococcal infection, when treatment of the infection is delayed or not completed.

There are risk factors that increase the chances of developing a heart murmur

If there is a history of valvular heart disease in the family, the chances of having heart defects or a heart murmur will be higher.
As a consequence of medical conditions, including untreated hypertension, endocarditis, high blood pressure in the lungs, secretion of hormones by cancer cells, chronic diseases such as lupus or arthritis, and rheumatic fevers.

Risk factors for children are

Presence of diseases during pregnancy, such as diabetes and rubella infection, which increase the risk for the child to develop congenital heart disease or heart murmur.
Taking certain medications, drug and alcohol intake, which cause coronary heart disease in the foetus.

What are the symptoms?

If heart murmurs are innocent, there will be no particular symptoms, in fact their diagnosis is most often casual.

Abnormal murmurs, on the other hand, are accompanied by symptoms.

In infants, there will be insufficient nutrition and slowed growth, shortness of breath especially during physical activity, dizziness, chest pain, cyanotic skin and excessive sweating.

What are the consequences?

Benign murmurs disappear on their own over time; abnormal murmurs lead to clinical complications such as heart failure and syncope.

Heart murmurs: how can they be prevented?

If there is already a diagnosis of a heart murmur, regular checks should be performed to keep an eye on the presence of the murmur and its severity, using a phonocardiogram.

Other tests that can be performed are chest X-ray, electrocardiogram and echocardiography.

As for treatment, benign heart murmurs are common at a young age and heal over time.

Since it is not a real pathology, there is no correction for the heart murmur, but there will be therapies aimed at correcting pathologies and abnormalities that have caused it.

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