Heart Murmurs: Causes, Symptoms, Diagnosis and Treatment

Author: Thomas C. Weiss
Published: 21 Dec 2012 - Updated: 4 Oct 2026
Publication Type: Informative

Table of Contents:
Synopsis - Definition - Overview - FAQs - Insights, Updates - Related Content

Synopsis

This information explains what a heart murmur is, how blood normally moves through the heart's four chambers and valves, and why turbulent flow produces the whooshing sound a clinician hears through a stethoscope. It separates harmless innocent murmurs, which are heard in roughly one-third to three-quarters of children at some point between ages 1 and 14, from abnormal murmurs caused by congenital heart defects, heart valve disease or endocarditis, and it covers symptoms, testing, treatment and prevention. The material is useful because it draws its figures from the agencies and professional bodies that publish them, including the National Heart, Lung, and Blood Institute, the Centers for Disease Control and Prevention, the American Heart Association and the World Health Organization, and because it speaks to the people most likely to be affected - parents of newborns, older adults with age-related valve changes, people with disabilities who may have trouble reporting symptoms, and the caregivers who support them.*

At a Glance

• 1 - Echocardiography, a painless ultrasound scan, is the most common test used to diagnose a heart valve problem.
• 2 - Murmur loudness is graded from 1 to 6, from very faint to loud enough to hear with the stethoscope off the chest.
• 3 - Heart defects affect nearly 1% of U.S. births, about 40,000 babies a year, and about 1 in 4 of them has a critical defect.
• 4 - Rheumatic heart disease, which follows untreated strep throat, affects an estimated 55 million people worldwide and claims about 360,000 lives each year.

Topic Definition

Heart Murmur

A heart murmur is an extra or unusual sound, typically a whooshing, swishing or blowing noise, heard through a stethoscope during the heartbeat and produced by turbulent blood flow through the heart's chambers, valves or nearby blood vessels. Murmurs are classified as innocent, meaning they occur in a structurally normal heart and need no treatment, or abnormal, meaning they result from an underlying condition such as a congenital heart defect, a narrowed or leaking heart valve, or an infection of the heart lining. Clinicians describe a murmur by its timing in the heartbeat cycle, its location on the chest and its loudness on a scale of 1 to 6. A heart murmur is a physical finding and not a disease in itself, so its significance depends entirely on its cause.

Overview

A heart murmur is an extra or unusual sound - often described as whooshing, swishing or blowing - that a health care professional hears through a stethoscope during the heartbeat cycle. The sound is made by turbulent blood flow in or near the heart [MedlinePlus, 2026]. Murmurs can be present at birth (congenital) or develop later in life. Many are harmless, while others point to a problem with a heart valve or with the structure of the heart. A murmur can also appear whenever blood moves through the heart faster than usual, as it does with pregnancy, fever, anemia, exercise, emotional stress or an overactive thyroid gland (hyperthyroidism) [MedlinePlus, 2026].

The Human Heart

The heart has four chambers - two upper chambers called atria and two lower chambers called ventricles. The right and left sides are divided by walls of tissue known as the atrial septum and the ventricular septum. Four valves - the tricuspid, pulmonary, mitral and aortic valves - sit between the chambers and at the exits of the ventricles. The valves do not pump blood. They open and close with each heartbeat so that blood moves in the right direction and does not flow backward [National Heart, Lung, and Blood Institute, 2025].

How the Heart Works

Each heartbeat has two phases: systole, when the ventricles contract and pump, and diastole, when the chambers relax and fill with blood. Oxygen-poor blood returns from the body through the superior and inferior vena cava into the right atrium, then passes through the tricuspid valve into the right ventricle. During systole, the right ventricle sends this blood through the pulmonary valve into the pulmonary artery and on to the lungs.

In the lungs, red blood cells pick up oxygen, and carbon dioxide - a waste product of metabolism - is removed. Oxygen-rich blood returns through the pulmonary veins to the left atrium and passes through the mitral valve into the left ventricle. The left ventricle then generates the high pressure needed to push blood through the aortic valve into the aorta, which carries it to the tissues of the body [National Heart, Lung, and Blood Institute, 2025].

A murmur is heard when blood does not move smoothly through the heart and turbulence occurs. Clinicians describe a murmur by where on the chest it is heard, by whether it falls in systole or diastole, and by its loudness, which is graded from 1 to 6. A grade 1 murmur is very faint and heard only with special effort, while a grade 6 murmur is loud enough to be heard with the stethoscope not quite touching the chest [American Heart Association, 2026a]. Not every murmur is dangerous, but a murmur can be the first sign of a structural problem and is worth having checked.

Causes of Heart Murmurs

Innocent Murmurs

Many heart murmurs are harmless and are called innocent, functional or physiologic murmurs. They happen when blood moves quickly through a normal heart, and no heart disease is present. About one-third to three-quarters of children have an innocent murmur at some time between ages 1 and 14. Most of these fade by adulthood, although some remain for life without causing problems [American Heart Association, 2026a]. In adults, an innocent murmur is often tied to a temporary state that makes the heart beat faster or harder, such as anemia, fever, pregnancy or hyperthyroidism.

Congenital Heart Defects

Abnormal murmurs in babies and children are most often caused by a congenital heart defect - a problem with the valves, the septa, or the arteries and veins that carry blood to and from the heart. More complex forms of congenital heart disease may involve several of these at once. Heart defects affect nearly 1% of births in the United States, or about 40,000 babies each year, and about 1 in 4 of those babies has a critical heart defect [Centers for Disease Control and Prevention, 2025a]. Some simple defects close or improve on their own, while others need a catheter procedure or surgery [National Heart, Lung, and Blood Institute, 2022a].

Patent ductus arteriosus (PDA) can cause a murmur in newborns. Before birth, the aorta and the pulmonary artery are connected by a short vessel, the ductus arteriosus, which is part of normal fetal circulation. Soon after birth this vessel is supposed to close. When it stays open, a murmur may be heard. Small openings may close on their own over time [National Heart, Lung, and Blood Institute, 2022b]. When they do not, doctors may use medicines such as indomethacin, ibuprofen or acetaminophen to help the vessel close, or close it with a catheter procedure [National Heart, Lung, and Blood Institute, 2022a]. In some babies born with another serious heart defect, an open ductus helps maintain circulation until that defect can be treated.

Heart Valve Disease

In adults, an abnormal murmur usually involves a heart valve that does not work properly [American Heart Association, 2026a]. Heart valve disease affects an estimated 2.5% of U.S. adults, and more than 28,000 deaths in the United States each year are due to it [Centers for Disease Control and Prevention, 2026]. Any of the four valves can be affected. Symptoms depend on how badly the valve is damaged and how far the normal pattern of blood flow is disturbed, and each valve problem tends to produce a murmur with its own timing and character.

• Valve stenosis - the valve opening is narrowed and stiff, so the valve cannot open fully. It usually develops over time, from calcium deposits that build up with age, from scarring after rheumatic fever, or from a congenital defect. The heart muscle has to work harder to push blood through the smaller opening, which can eventually lead to heart failure.
• Valve regurgitation - the valve does not close completely, so blood leaks backward against the normal direction of flow. A single valve can have both stenosis and regurgitation.
• Valve sclerosis - the valve, most often the aortic valve, becomes thickened and stiff with age but does not yet significantly block blood flow. It is associated with atherosclerotic heart disease.
• Valve prolapse - the flaps of a valve, most often the mitral valve, bulge backward when the valve closes, which may allow some leaking.

Endocarditis

Infective endocarditis is an infection of the inner lining of the heart. It most often affects the heart valves and can destroy them. It is usually caused by bacteria that enter the bloodstream from somewhere else in the body, such as the mouth or the skin. People with an artificial heart valve, a previous episode of endocarditis or certain congenital heart conditions are at the highest risk of serious complications [American Heart Association, 2026b].

Holes in the Heart

A hole in the septum, the wall that divides the chambers of the heart, can also be the source of a murmur. An atrial septal defect (ASD) is a hole in the wall between the two upper chambers. A ventricular septal defect (VSD) is a hole in the wall between the two lower pumping chambers, and it is the most common type of heart defect [Centers for Disease Control and Prevention, 2025a]. Many VSDs are small and close on their own, with regular checkups to confirm that they have [Centers for Disease Control and Prevention, 2025b]. An ASD may also close as the heart grows during childhood [National Heart, Lung, and Blood Institute, 2022b].

Heart Murmur Symptoms

A heart murmur itself causes no symptoms and usually cannot be heard by the person who has it. An innocent murmur has no consequences at all. When symptoms do occur, they come from the underlying heart condition and not from the sound.

Newborns with congenital heart disease may have trouble breathing or may be cyanotic, meaning the skin, lips or nails take on a bluish tint because the blood is carrying too little oxygen. Newborn pulse oximetry screening, which measures the oxygen level in the blood, is used to help find these babies early [National Heart, Lung, and Blood Institute, 2022c]. Some infants with heart problems have difficulty feeding and do not grow and develop as expected. In children who are otherwise well and developing normally, the great majority of murmurs are harmless.

In adults, heart valve disease may cause shortness of breath, chest pain, dizziness, fatigue, swelling of the feet, ankles or abdomen, and palpitations or an irregular heartbeat [Centers for Disease Control and Prevention, 2026]. These problems often come on slowly, and older adults may put tiredness or breathlessness down to aging. A new or worsening symptom is a reason to see a health care professional. For people who find it hard to describe how they feel, including some people with cognitive or communication disabilities, a caregiver can help by noting changes in breathing, energy, appetite or swelling and passing them on to the care team.

How Heart Murmurs Are Diagnosed

Most murmurs are found during a routine physical examination. If the sound suggests more than an innocent murmur, or if there are symptoms, further tests are ordered. Echocardiography - a painless ultrasound scan that shows the heart's chambers and valves as they move - is the most common test used to diagnose a heart valve problem. An electrocardiogram, a chest X-ray or a stress test may also be used [National Heart, Lung, and Blood Institute, 2022c].

Treatment for Heart Murmur

Treatment depends on the cause of the murmur and on the person's overall health. Innocent murmurs need no treatment or follow-up, and a murmur brought on by fever, anemia or an overactive thyroid usually settles once that condition has passed or been treated. Murmurs linked to an infection of the heart valves are treated with antibiotics, and a badly damaged valve may still need surgery afterward.

For heart valve disease, medicines can control blood pressure and heart rate and help prevent blood clots, which eases the strain on the heart but does not correct the valve itself. When a valve is seriously narrowed or leaking, it can be repaired or replaced. Options now include open-heart surgery, balloon valvuloplasty to stretch a narrowed valve, and transcatheter aortic valve replacement (TAVR), in which a new valve is delivered through a catheter without open-heart surgery [National Heart, Lung, and Blood Institute, 2022d]. Less invasive procedures have made treatment possible for many older adults and others for whom major surgery carries high risk.

In infants and children, a septal defect that is large or causing symptoms can be closed with a catheter procedure or with heart surgery [National Heart, Lung, and Blood Institute, 2022a]. Many children do well afterward, though some people with a repaired heart defect need checkups with a heart specialist into adulthood. People whose murmur signals a mild structural problem are often simply monitored, with treatment considered only if symptoms develop or tests show the heart is under strain.

It is important to remember that a heart murmur is a physical finding, not a disease. It is a sound, and what it means for a person's health depends entirely on what is causing it and on how that cause affects the way the heart works. The goal of treatment is to restore normal blood flow through the heart so the person can return to an active life.

Prevention and Heart Health

Rheumatic fever is an inflammatory reaction that can follow an untreated strep throat infection and leave the heart valves permanently scarred. It is much less common in the United States than it once was because most strep infections are treated early with antibiotics [Centers for Disease Control and Prevention, 2026]. Worldwide the picture is different. Rheumatic heart disease affects an estimated 55 million people and claims about 360,000 lives each year, the large majority in low- and middle-income countries [World Health Organization, 2025].

Congenital defects and age-related valve changes cannot always be prevented, but a heart-healthy lifestyle may lower the risk of some valve problems. That means keeping blood pressure, cholesterol and diabetes under control, staying physically active, managing weight and not smoking [National Heart, Lung, and Blood Institute, 2022d]. Good oral health, with regular brushing, flossing and dental care, also lowers the risk of endocarditis [American Heart Association, 2026b].

This article is general information and not a substitute for medical care. Anyone who has been told they have a heart murmur, or who is caring for someone who has, should ask a doctor or cardiologist what kind of murmur it is and whether any follow-up is needed.

Frequently Asked Questions

NOTE: Researched FAQs by Disabled World (DW)

Can a heart murmur be felt as well as heard?

Sometimes. Louder murmurs, generally those graded 4 or higher on the 6-point scale, can produce a vibration called a thrill that a clinician feels with a hand placed over the heart. Fainter murmurs can only be heard with a stethoscope.

Can a child with an innocent heart murmur play sports?

Yes. Children with an innocent murmur do not need medication, a special diet or limits on physical activity, and they can take part in sports and play like any other child. Restrictions are only considered when a murmur is caused by an underlying heart condition, and a doctor will advise on that.

Is a heart murmur the same as an irregular heartbeat?

No. A murmur is a sound made by blood moving through the heart, while an irregular heartbeat, or arrhythmia, is a problem with the rate or rhythm of the heartbeat. The two are separate findings, although some heart valve conditions can cause both.

How soon after strep throat can rheumatic fever develop?

Rheumatic fever usually appears about 1 to 5 weeks after a group A strep infection such as strep throat or scarlet fever that was not treated. It is most common in school-age children between 5 and 15 years old, and treating strep infections with antibiotics prevents it.

Who may need antibiotics before dental work to prevent endocarditis?

Preventive antibiotics before certain dental procedures may be recommended for people at the highest risk, including those with an artificial heart valve, a previous episode of endocarditis, certain congenital heart conditions, or a heart transplant with valve disease. Most people with a heart murmur do not need them, and a cardiologist or dentist can confirm what applies.

How many babies are born with a ventricular septal defect each year?

About 42 of every 10,000 babies in the United States are born with a ventricular septal defect, which works out to about 16,800 babies each year. The size of the hole affects whether a murmur can be heard and whether treatment is needed.

What is the difference between mechanical and biological replacement heart valves?

Biological valves are made from animal tissue and do not require lifelong blood thinners, but they wear out and eventually need to be replaced. Mechanical valves are made from carbon or other sturdy material and last longer, but people who have them need to take blood-thinning medicine for life.

How many people in the United States are living with a congenital heart defect?

A national estimate for 2010 put the figure at about 1 million children and 1.4 million adults living with a heart defect in the United States. Some of them need checkups with a heart specialist throughout life.

References:

• American Heart Association. (2026a). Heart murmurs.
• American Heart Association. (2026b). Infective endocarditis.
• Centers for Disease Control and Prevention. (2025a). Data and statistics: Congenital heart defects (CHDs).
• Centers for Disease Control and Prevention. (2025b). Ventricular septal defect.
• Centers for Disease Control and Prevention. (2026). About heart valve disease.
• MedlinePlus. (2026). Heart murmurs. National Library of Medicine.
• National Heart, Lung, and Blood Institute. (2022a). Congenital heart defects: Treatment.
• National Heart, Lung, and Blood Institute. (2022b). Congenital heart defects: Types.
• National Heart, Lung, and Blood Institute. (2022c). Heart valve diseases: Diagnosis.
• National Heart, Lung, and Blood Institute. (2022d). Heart valve diseases: Treatment.
• National Heart, Lung, and Blood Institute. (2025). How the heart works: How blood flows through the heart.
• World Health Organization. (2025). Rheumatic heart disease.

Insights, Analysis, and Developments

Editorial Note: A heart murmur is best understood as a clue and not a verdict - the same whooshing sound can come from a healthy child's fast-flowing blood or from a valve that is slowly failing, and only an examination and, where needed, a heart scan can tell the two apart. That distinction matters most for older adults, since heart valve disease accounts for more than 28,000 deaths in the United States each year and its early signs of tiredness and breathlessness are easily mistaken for ordinary aging, and for families of infants, since ventricular septal defects are the most common heart defect yet many are small and close without treatment. With catheter-based valve replacement and repair now sitting alongside open-heart surgery, more people who were once considered too frail for an operation have options, which makes it all the more worthwhile for patients and caregivers to ask what kind of murmur has been found and what follow-up it calls for.*

Author Credentials: Thomas C. Weiss is a researcher and editor for Disabled World. Thomas attended college and university courses earning a Masters, Bachelors and two Associate degrees, as well as pursuing Disability Studies. As a CNA Thomas has provided care for people with all forms of disabilities. Explore Thomas' complete biography for comprehensive insights into his background, expertise, and accomplishments.

* Editorial additions by Ian C. Langtree.