Heart Murmur - Causes, Symptoms and Treatment

Heart murmur is the name we give to the sound the blood makes when it passes through a heart valve with some structural change. However, not every patient with a heart murmur must have heart disease.

Blood circulation in heart
Blood circulation in heart

How the heart murmur arises

The blood flows continuously and in a single direction into the cardiac cavities, producing no noise. That "tum-tum" we usually hear when listening to the heart is sound produced by the closing of the heart valves.

The heart murmur is a sound that can be heard when there is interference in the blood flow that passes through these valves. Blow, therefore, usually arises from problems in the heart valves. However, in children and young healthy people it may be an innocent finding, with no clinical significance.

Breathing is usually identified during the physical examination by cardiac auscultation with the stethoscope.

Before we speak of the heart murmur itself, we must take a quick step in the anatomy and basic physiology of the heart. To understand terms such as systolic murmur, murmur of regurgitation, or murmur of mitral insufficiency, one must first understand what the heart valves are and how the blood normally flows between the structures of the heart. Read the next few lines carefully because your understanding is essential for understanding the rest of the text. I'll use some pictures to help.

How heart works

Heart anatomy
Heart anatomy
The heart is divided into 4 chambers:
  • Left atrium
  • Right atrium
  • Left ventricle
  • Right ventricle

The blood reaches the heart in two ways:

1. The blood that reaches the left part of the heart comes from the lungs, enters the left atrium, passes to the left ventricle and is then pumped back to the body. This blood is represented by the red color in the figure below.

2. The blood, after passing through the body, returns to the heart. Now it arrives through the right atrium, passes into the right ventricle and is finally pumped towards the lungs, where after oxygenated it returns to the heart through the left atrium as explained in item 1. This blood is represented by the blue color in the figure below.

The blood does not circulate freely inside the heart. There are 4 valves that serve as door, opening and closing to prevent blood from returning from one cavity to another. Once inside the ventricles, the blood no longer returns back to the atria, and when inside the arteries, the blood also no longer returns to the ventricles. Thanks to the valves, the blood flows in only one direction: vein → atrium → ventricle → artery.

Valves of the right heart:
  • Tricuspid valve - is located between the right atrium and the right ventricle.
  • Pulmonary valve - is located between the right ventricle and the pulmonary artery.

Valves of the left heart:
  • Mitral valve - is located between the left atrium and the left ventricle.
  • Aortic valve - is located between the left ventricle and the aorta artery.

How is heart murmur

As we all know, when we listen to the heart with a stethoscope it is possible to hear it beating: "tum-tum ... tum-tum ... tum-tum ... tum-tum".

But why does the heart make two sounds at a time ("tum-tum ... tum-tum ... tum-tum") instead of just one ("tum ... tum ... tum")?

Actually, contrary to what one thinks, these sounds are not by the heart beat, but by the closing of their valves. The first "tum" is produced by the closure of the mitral and tricuspid valves that prevent the blood from returning to the atria while the ventricles contract. The second "tum" occurs by closing the aortic and pulmonary valves, preventing the blood that has already been released towards the arteries to return to the ventricles. While the mitral and tricuspid are closed, the aortic and pulmonary are open and vice versa.

This "tum", caused by the valves, is called the heart sound or sound. We describe the normal heartbeat as 2-stroke or 2-stroke heart sounds.

Breathing occurs every time there is a defect in the valves, causing blood to not flow properly into the heart.

There are 2 basic defects:
  • Valve stenosis: When the valve becomes hardened and can no longer fully open, blood ends up having difficulty moving from one chamber to another. This whirlwind produces the breath. If the stenosed valve is the aortic valve, we call it aortic stenosis. If the defect is in the tricuspid valve, blow by tricuspid stenosis, and so on.
  • Regurgitation or valve insufficiency: When the valve does not close completely, it eventually allows blood to flow back in the opposite direction. This type of retrograde flow also produces whirling and, consequently, a blow. Therefore, we have the murmur of mitral insufficiency, aortic insufficiency, etc.

While the normal valve produces a "tum-tum" sound, sick and blown valves do something like "tuuuush-tum" or "tum-tuuuush."

What is systolic and diastolic murmur?

Systole is the time when the ventricles are contracting, expelling the blood towards the arteries. Diastole is the time when the ventricles are relaxed, filling with blood coming from the atria.

In systole, the aortic and pulmonary valves are open and the mitral and tricuspid valves are closed. In diastole the opposite occurs. Therefore, the first "tum", closure of the mitral and tricuspid valves, occurs in systole. The second "tum", due to the closure of the aortic and pulmonary valves, occurs in the diastole. When the murmur occurs shortly after the first "tum", ie "tuuush-tum", we call them systolic murmur. If the murmur occurs after the second tum, ie "tum-tuuush" we are facing a diastolic murmur.
  • Systolic murmurs are caused by stenoses of the aortic or pulmonary valves, or by insufficiency of the mitral or tricuspid valves.
  • Diastolic murmurs occur due to stenoses of the mitral or tricuspid valves, or due to insufficiency of the aortic or pulmonary valves.

The woodwinds are graduated from I to VI.
  • grade I - blow very discreet, inaudible for those who do not have trained ears
  • grade II - medium puff, easily audible by stethoscope
  • grade III - high blow
  • grade IV - very high blow that can be felt by hand when touching the patient's chest
  • grade V - Very loud blowing that can be heard even without touching the stethoscope on the patient's chest
  • grade VI - blowing so loud that it can be heard even without a stethoscope

The greater the degree of the murmur, the more severe is the valve disease.

How to tell if a murmur is benign or a sign of heart disease

Up to 50% of children without heart problems may have a heart murmur. In general, the murmur disappears spontaneously with growth. It usually occurs due to the disproportion between the sizes of the heart structures and their vessels. In the adult, the breath can also be benign, but it is not as common as in children.

The benign murmur is always systolic and of low intensity (grade I or II). Diastolic or degree blows greater than III are always pathological. The benign murmur usually becomes more intense when the patient lies and disappears, or almost when the patient sits or stands.

In children, heart diseases that cause murmurs are usually congenital, that is, birth defects, which causes the pathological murmur to be accompanied by symptoms such as developmental problems, asthenia, lack of appetite, cyanosis (purplish lips), etc.

In adulthood, valve diseases develop over time. If you have symptoms of heart failure, such as shortness of breath, edema, easy tiredness, chest pain, etc., it is easy to know that the heart murmur is indicative of heart valve disease. The problem is that in adults, the murmur may be the first sign of heart disease, preceding in years the onset of symptoms of heart failure.

Some conditions may cause the onset of a temporary heart murmur, unrelated to valve disease. This breath disappears as soon as its cause is eliminated. Are they:

Diseases caused by heart murmur

The pathological murmur is one that occurs secondary to heart disease. As already said, in children it occurs due to congenital diseases, whereas in adults it arises after acquired heart diseases during the life.

In children, in addition to valve lesions, pathological heart murmur may also occur due to a defect in the septum that separates the ventricles. Usually the left and right ventricles never communicate, but defects during the formation of the wall between both can cause small holes that allow the passage of blood between one and the other. This abnormal blood flow also produces breath.

In adults, murmurs occur due to valve defects, whether stenoses or insufficiencies. The main causes of acquired heart murmur are:
  • Prolapse of the mitral valve
  • Rheumatic fever
  • Infective endocarditis
  • Calcification of the valve by age. They occur most commonly in the mitral and aortic valves

Injuries to the heart valves usually lead to heart failure, but the reverse can also occur. An insufficient heart is usually dilated causing the valve leaflets to move away, causing regurgitation of the blood flow. Therefore, every patient with moderate to severe heart failure, for reasons other than valve injury, may also experience heart murmur. The difference is that in this case, the murmur appears after the symptoms of heart failure are already present.


A good doctor can only by physical examination establish the cause of the heart murmur. However, not all physicians are cardiologists and the breath is not always easy to evaluate.

The definitive examination for evaluation of the murmurs and consequently of the heart valves is Doppler echocardiography. This test allows not only identifying the type of valve lesion, but also measuring the degree of stenosis or insufficiency and evaluating the damage to the heart as a result of these lesions.


It is good to remember that the breath is not a disease, but a sign of disease. What worries is not the breath itself, but the disease that is causing it. Winds caused by anemia or fever, disappear after treatment of these.

In the case of valve damage, the treatment is more complex. If the valve injury does not cause more effort to the heart and there are no signs of heart failure, the treatment is done clinically. In the most severe situations, with an important valve lesion, surgery may be indicated to replace the defective native valve with an artificial valve.

Benign windmills do not need any treatment.

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