Introduction

Heart murmurs are sounds — such as whooshing or swishing — made by rapid, choppy (turbulent) blood flow through the heart. The sounds can be heard with a device called a stethoscope. A typical heartbeat makes two sounds like “lubb-dupp” (sometimes described as “lub-DUP“) when the heart valves are closing^[1]. There is no way to prevent congenital heart defects that cause some heart murmurs.

Research^[2] estimates that heart murmurs affect up to 72% of children, but often, the murmur will go away as they grow older. However, some people may live with a heart murmur into adulthood. In adults, some heart diseases — including heart valve disease — can cause heart murmurs. Most heart murmurs aren’t dangerous, but sometimes, they can be a sign of a heart problem. Heart murmurs are classed as either: Innocent heart murmur – when your heart still beats normally but makes extra sounds when your blood flows through your heart faster than usual^[3].

Heart murmurs are unique sounds from the heart produced when blood flows across a heart valve or blood vessel.^[4] They happen when turbulent blood flow creates a sound that is loud enough for a medic to hear with a stethoscope^[5]. Turbulent blood flow is not smooth^[6], and the sound differs from normal heart sounds by their characteristics. For example, heart murmurs may have a distinct pitch, duration and timing.^[7] Heart murmurs are quite common and don’t necessarily indicate a health problem, especially in children, but they should be evaluated because they may signal a heart problem or other health issue.

Picture Credit: “File:Diagram of the human heart (cropped).svg” by Wapcaplet is licensed under CC BY-SA 3.0.

The main way that health care providers examine the heart on physical exam is heart auscultation^[8]/^[9]. Another clinical technique is palpation, which can detect by touch when such turbulence causes vibrations called cardiac thrill.^[10]

Murmurs are of various types and are important in detecting cardiac and valvular pathologies (i.e. they can be a sign of heart diseases or defects).

Phonocardiograms from normal and abnormal heart sounds. Attribution: Madhero88, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0&gt;, via Wikimedia Commons. Page URL: https://commons.wikimedia.org/wiki/File:Phonocardiograms_from_normal_and_abnormal_heart_sounds.svg This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.

There are three main types of heart murmurs^[11]:

• Systolic murmur – when the heart pumps blood to the rest of the body. Systolic murmurs are divided into ejection murmurs (due to blood flow through a narrowed vessel or irregular valve) and regurgitant murmurs^[12].
• Diastolic murmur – when the heart relaxes between beats to fill up with blood. Diastolic murmurs are due to a narrowing (stenosis) of the mitral or tricuspid valves or regurgitation of the aortic or pulmonary valves^[13].
• Continuous murmur – throughout the heartbeat.

A functional murmur or “physiologic murmur” is a heart murmur primarily caused by physiologic conditions outside the heart. Other types of murmurs are due to structural defects in the heart itself. Functional murmurs are benign (an “innocent murmur“).^[14]

Most of the time, murmurs are normal variants and occur at various ages due to changes in the body as we get older. For example, chest size, blood pressure, flexibility or rigidity of structures. Normal variants are present without a cardiovascular problem.^[15]

Murmurs may also be the result of various problems. For instance, narrowing or leaking of valves or the presence of abnormal passages through which blood flows in or near the heart.^[16] Murmurs caused by a disease process are pathologic murmurs. Pathologic murmurs may need evaluation by a cardiologist.

Heart murmurs are frequently categorised by timing. These include systolic heart murmurs, diastolic heart murmurs, or continuous murmurs. These differ in the part of the heartbeat they make sounds, during systole or diastole. But continuous murmurs create sound throughout both parts of the heartbeat. Continuous murmurs^[17] are not placed into the categories of diastolic or systolic murmurs.

Murmurs have several characteristics. These include timing, shape, location, radiation, intensity, pitch and quality:

• Timing refers to whether the murmur is a systolic, diastolic, or continuous murmur.
• Shape refers to the intensity over time. Murmurs can be crescendo, decrescendo or crescendo-decrescendo. Crescendo murmurs increase in intensity over time. Decrescendo murmurs decrease in intensity over time. Crescendo-decrescendo murmurs have both shapes over time. These have progressive increase in intensity, peak, and progressive decrease in intensity. Crescendo–decrescendo murmurs resemble a diamond or kite shape.
• Location refers to where the heart murmur is usually heard best. There are four places on the anterior chest wall to listen for heart murmurs. Each location roughly corresponds to a specific part of the heart. Health care providers listen to these areas with a stethoscope.

• Position for auscultation: The patient is most often lying on their back (supine) with the head of the bed at a slight upward angle. The head of the bed is usually at a 30-degree upward angle. Usually, the health care provider stands to the right of the person they are examining.^[18] Below are positional changes that one may use:
  • Left lateral decubitus (lying on the left side). This will decrease the distance from the wall of the chest to the apex of the heart and help to examine the point of maximal impulse. Also, this will help to hear extra heart sounds (S3 or S4).^[19]
  • With the patient sitting upright.
  • With the patient seated, leaning forward and holding their breath after exhalation. This will decrease the distance of the chest wall to the left ventricular outflow tract and help find the presence of an aortic regurgitation murmur.[20]
• Radiation refers to where the sound of the murmur travels. The rule of thumb is that the sound radiates in the direction of the blood flow.
• Intensity refers to the loudness of the murmur with grades according to the Levine scale^[21], from 1 to 6.^[22] The grading gives a number to the intensity from 1 to 6. The palpable murmur is known as thrill, which can be felt at grade 4 or higher. The Levine scaling system provides accuracy, consistency, and interrater agreement, which are essential for diagnostic purposes, particularly to distinguish innocent from pathological murmurs. The Levine scale is usually written down as a fraction of 6 and in Roman numerals, as in a scale of II/VI.^[23]

Symptoms
HarvardHealth^[24] says that an innocent murmur does not cause any symptoms. For other types of heart murmurs, symptoms vary depending on the cause. In general, when a heart murmur significantly interferes with the heart’s ability to pump blood, you can experience one or more of the following symptoms:

• Shortness of breath
• Light-headedness
• Episodes of rapid heartbeat
• Chest pain
• Decreased tolerance for physical exertion and, in later stages, symptoms of heart failure

In addition to the above, symptoms of worrisome heart murmurs may include^[25]:

• Blue or grey fingernails or lips
• Cough that doesn’t go away
• Dizziness
• Swollen liver
• Swollen neck veins
• Fainting
• Heavy sweating with little or no activity
• In infants, poor appetite and lack of growth
• Swelling or sudden weight gain

The British Heart Foundation^[26] add one more symptom: not growing at a normal rate and a lack of appetite (in babies and children only).

Advice from the British Heart Foundation^[27]
Abnormal heart murmurs are rare, especially in babies or young people. If your doctor thinks you might have an abnormal heart murmur, they will arrange tests to see how your heart is working. If your healthcare team diagnoses a problem with your heart, they will discuss treatment options with you. Your healthcare team will understand if you feel worried and can support you. It’s common for babies and children to experience ‘innocent’ heart murmurs. They usually disappear by reaching puberty (between the ages of 8-14) and don’t need any treatment. Your child might have harmless murmurs come and go depending on their breathing, their heart rate and how active they’re being at the time.

You should call 999 immediately if you’re experiencing:

• pain in your chest or upper body
• difficulty breathing or shortness of breath.

Picture Credit: “Heart Exam ECG” by medipics1066 is licensed under CC BY 2.0.

Tests^[28]
Because specific heart problems are associated with specific types of murmurs, your doctor often will make a tentative diagnosis based on your medical history, symptoms and the murmur’s distinctive sound and timing (whether the murmur occurs when the heart is pumping or resting). As part of your medical evaluation, your doctor may order diagnostic tests, which may include:

• Electrocardiography (ECG) – This painless, non-intrusive procedure measures the electrical activity of the heart.
• Chest X-ray – This is used to check for an enlarged heart and certain congenital abnormalities.
• Echocardiography – This noninvasive test uses sound waves to create an image of the heart’s structure, including the structure of its valves.
• Doppler echocardiography – This test is similar to echocardiography, but it creates an image of the heart’s blood flow patterns rather than its structure.
• Cardiac catheterisation – In this test, a small, sterile tube called a catheter is guided into the heart to measure pressures and oxygen levels in the heart’s chambers. A dye is injected through the catheter to produce an X-ray image of the heart’s internal structure and blood flow patterns.
• Blood tests – Blood tests are used to check for infection in people with suspected endocarditis^[29] or Pericarditis^[30]:
• Endocarditis is a rare and potentially fatal infection of the inner lining of the heart (the endocardium). It’s most commonly caused by bacteria entering the blood and travelling to the heart. Although the heart is usually well protected against infection, it may be easier for bacteria to bypass the immune system in people who have an artificial (prosthetic) heart valve – valve replacement surgery is increasingly being used when people experience narrowing of one of their heart valves, congenital heart disease (where a person is born with heart defects), hypertrophic cardiomyopathy (where the heart muscle cells have enlarged and the walls of the heart chambers thicken), or damaged heart valves – because of infection or heart disease
• With Pericarditis, the pericardium gets inflamed, and blood or fluid can leak into it. The pericardium is the protective fluid-filled sac around the heart. It is difficult to confirm the exact cause of Pericarditis, but usually, it’s a viral infection. Pericarditis causes chest pain and a high temperature. It’s not usually serious, but it can cause serious health problems. Get medical advice if you have chest pain.

In another test (Electrophysiology study), your doctor may attach electrodes to your heart through a catheter. When the electrodes are in place, your doctor can send electric pulses through and record how the heart responds^[31].

Diagnosis^[32]
Heart murmurs may be detected during a physical exam carried out for another reason. The GP or cardiologist may ask questions about personal and family medical history. They listen to the heart using a stethoscope and consider several issues when listening to the heart to tell if a murmur is innocent or worrisome, such as:

• Volume – How loud is the heart murmur on a scale from 1 to 6? The loudest heart murmur is 6 (see note 21 re the Levine scale).
• Location – Where in the heart is it? Does the sound spread to the neck or back?
• Pitch – Is it high-, medium- or low-pitched?
• Timing of the murmur – A murmur that occurs when blood leaves the heart (systolic murmur) generally is an innocent heart murmur. One that happens when the heart fills with blood (diastolic murmur) or throughout the heartbeat (continuous murmur) may signal a heart problem.
• Sound changes – Does exercising or changing body position affect or alter the sound?

Causes
Defective heart valves often cause non-innocent (or abnormal) heart murmurs. For example:

• a stenotic heart valve has a smaller-than-normal opening and can’t open completely, or
• a valve may also be unable to close completely, which leads to regurgitation (blood leaking backwards through the valve when it should be closed).

Certain congenital defects and other conditions such as pregnancy, fever, anaemia or thyrotoxicosis (a condition caused by an overactive thyroid gland) can also cause heart murmurs.^[33]

Young Children^[34]
Young children have small, slim chests, so their hearts are nearer to a stethoscope than those of teenagers and adults, and their heart rate is faster. Blood has to negotiate two tight bends as it flows through the heart. The flow of blood travelling through the heart and blood vessels in this way can also make a noise, and this is known as an ‘innocent’ murmur. Innocent murmurs can sometimes come and go, becoming noisier if the heart is beating fast – after exercise or with a fever – and quieter as a child sleeps. As the years go by, the heart rate slows, and the heart grows and lies deeper within the body. The normal bends within the heart become less tight, and an innocent murmur disappears. In rarer cases, a heart murmur can come from abnormal blood flow within the heart and blood vessels. This might be related to either a narrow or leaking valve or a hole in the wall (called a septal defect, a problem with the heart’s structure that a person is born with – congenital).

The following can increase the risk of heart murmurs in babies^[35]:

• Family history of heart problems linked to murmurs
• Uncontrolled diabetes in the mother during pregnancy
• German measles (rubella) in the mother during pregnancy
• Use of certain medications, alcohol or illegal drugs by the mother during pregnancy^[36]

Adults^[37]
In adults, abnormal murmurs are most often caused by damaged heart valves:

• Heart valves operate like one-way gates, helping blood flow in one direction between heart chambers and into and out of the heart. When disease or an infection damages a heart valve, it can cause scarring and affect how well the valve works. The valve may not be able to close properly so that blood can leak through. Or the valve may become too narrow or stiff to let enough blood through. When a damaged heart valve cannot close properly, it causes regurgitation. When the valve can’t let enough blood through, the problem is called stenosis.
• Heart valves can be damaged by heart disease or by infections like rheumatic fever or endocarditis. The normal wear and tear that comes with ageing can also cause damage.
• Some heart murmurs are caused by a thicker than normal heart, a condition called hypertrophic obstructive cardiomyopathy. When the heart muscle grows too large, it can get in the way of normal blood flow and cause a murmur.

Some medical conditions can increase the risk of heart murmurs, including:

• A rare cancerous tumour that releases certain chemicals into the bloodstream (carcinoid syndrome)
• A weakened heart muscle (cardiomyopathy)
• An infection of the lining of the heart (endocarditis)
• Anaemia
• Blood disorders marked by a high number of certain white cells, called eosinophils (hypereosinophilic syndrome)
• Certain autoimmune disorders such as lupus and rheumatoid arthritis
• Heart valve disease
• High blood pressure in the lungs (pulmonary hypertension)
• History of rheumatic fever
• Overactive thyroid (hyperthyroidism)

Treatment (including Medications)
Innocent heart murmurs don’t usually need treatment. If a fever or an overactive thyroid (hyperthyroidism) causes a murmur, it usually goes away when that condition is treated.

Treatment for a worrisome heart murmur depends on the cause. A worrisome heart murmur requires close monitoring by your GP or hospital cardiologist. Medications or surgery may be needed. Medications that might be used to treat heart conditions associated with murmurs include^[38]:

• Blood thinners (anticoagulants). This type of medicine prevents blood clots. Some conditions that cause heart murmurs are closely linked to irregular heartbeats (arrhythmias) that can cause blood clots.
  Blood clots increase the risk of strokes. Blood thinners include warfarin (Jantoven), clopidogrel (Plavix), apixaban (Eliquis), rivaroxaban (Xarelto), dabigatran (Pradaxa) and others.
• Water pills (diuretics). This medicine removes excess fluid from the body. A diuretic may be given to treat high blood pressure or other conditions that can make heart murmurs worse.
• Angiotensin-converting enzyme (ACE) inhibitors. This type of drug lowers blood pressure. High blood pressure can worsen underlying conditions that cause heart murmurs.
• Beta-blockers. A beta blocker lowers heart rate and blood pressure.

There’s a comprehensive list of treatments for heart and circulatory conditions on the British Heart Foundation website^[39].

Prognosis^[40]
The outlook for people with a heart murmur depends on the condition causing it. More often than not, children outgrow childhood murmurs, and a murmur with pregnancy goes after giving birth. Innocent heart murmurs are benign and do not usually require medical attention, and may go away over time.

Sometimes, heart murmurs continue for life without causing serious health problems, but abnormal heart murmurs, signal an underlying heart condition and require medical treatment – the prognosis depends on the cause and severity of the problem. When treating abnormal heart murmurs, the doctor must first determine the cause. Sometimes, people need surgery to repair a defective valve. Others may not need surgery and will be able to lead a relatively healthy life afterwards.

Heart valve disease is more common with age. Doctors can help people manage heart murmurs and improve the heart’s function. Healthy lifestyle choices can help you prevent heart disease. They can also help you treat the condition and prevent it from worsening. Your diet is one of the first areas you may seek to change, together with exercising more and stopping tobacco use.

Sources and Further Reading

• https://en.wikipedia.org/wiki/Heart_murmur
• https://www.medicalnewstoday.com/articles/326802
• https://www.mayoclinic.org/diseases-conditions/heart-murmurs/diagnosis-treatment/drc-20373175
• https://www.mayoclinic.org/diseases-conditions/heart-murmurs/symptoms-causes/syc-20373171
• https://www.bhf.org.uk/informationsupport/conditions/heart-murmurs
• https://www.nhs.uk/conditions/endocarditis/diagnosis/
• https://my.clevelandclinic.org/health/diseases/17083-heart-murmur
• https://www.webmd.com/heart-disease/guide/heart-murmur-causes-treatments
• https://www.health.harvard.edu/a_to_z/heart-murmur-a-to-z
• https://www.health.harvard.edu/heart-health/different-types-of-heart-murmurs
• https://www.heart.org/en/health-topics/heart-murmurs
• https://www.gosh.nhs.uk/conditions-and-treatments/general-medical-conditions/heart-murmurs-innocent/
• https://kidshealth.org/en/parents/murmurs.html
• https://www.hopkinsmedicine.org/health/conditions-and-diseases/heart-murmurs
• https://stanfordhealthcare.org/medical-conditions/blood-heart-circulation/heart-murmurs/types.html
• https://geekymedics.com/heart-murmurs/
• https://www.cedars-sinai.org/health-library/diseases-and-conditions/h/heart-murmurs.html
• https://www.yalemedicine.org/conditions/heart-murmur
• YouTube Video: HCL Learning: Structure of the Human Heart, at: https://youtu.be/qmpd82mpVO4
• YouTube Video: Learn How the Human Heart Works: Veative Labs, at: https://youtu.be/fqRy9poXZzM
• YouTube Video: British Heart Foundation: How does a healthy heart work? at: https://youtu.be/ep4cQrYFL0w
• Book: The Human Heart: A Basic Guide to Heart Disease, Illustrated, by Brendan Phibbs 3^rd February 2007, at: https://www.amazon.co.uk/Human-Heart-Basic-Guide-Disease/dp/0781767776

Picture Credit: “Doctor with a stethoscope” by wuestenigel is licensed under CC BY 2.0.

CAUTION: This paper is not medical advice. No advice is implied or given in articles published by us but is only for general information. You should always seek the advice of your GP or other qualified health provider with any questions you may have regarding a medical condition. This paper is compiled from the sources stated but has not been medically reviewed. It should never be used as a substitute for obtaining advice from a consultant Cardiologist or other qualified clinician/medical practitioner. If you have already been given dietary advice, you should not make changes without first talking to your GP, consultant or dietitian. Any medications mentioned may include names for US drugs which may have a different name to those available in the UK. The facts are believed to be correct as at the date of publication, but there may be certain errors and omissions for which we cannot be responsible. There is no implied endorsement or promotion of any organisation by the writer. The hyperlinks were valid at the date of publication.

1. Source: https://www.mayoclinic.org/diseases-conditions/heart-murmurs/symptoms-causes/syc-20373171 ↑
2. See: https://www.ncbi.nlm.nih.gov/books/NBK507849/ ↑
3. Source: https://www.bhf.org.uk/informationsupport/conditions/heart-murmurs ↑
4. Source: Patient education: Heart murmurs (The Basics)”. UpToDate. 25 March 2022. ↑
5. Source: Braunwald’s heart disease : a textbook of cardiovascular medicine. Douglas P. Zipes, Peter Libby, Robert O. Bonow, Douglas L. Mann, Gordon F. Tomaselli, Eugene Braunwald (Eleventh ed.). Philadelphia, PA. 2019. ISBN 978-0-323-46342-3. ↑
6. Source: Hurst’s the heart. Valentin Fuster, Robert A. Harrington, Jagat Narula, Zubin J. Eapen (14th ed.). New York. 2017. ISBN 9780071843249. ↑
7. Sources: Braunwald’s heart disease : a textbook of cardiovascular medicine. Douglas P. Zipes, Peter Libby, Robert O. Bonow, Douglas L. Mann, Gordon F. Tomaselli, Eugene Braunwald (Eleventh ed.). Philadelphia, PA. 2019. ISBN 978-0-323-46342-3. Bickley, Lynn S. (2021). Bates’ guide to physical examination and history taking. Peter G. Szilagyi, Richard M. Hoffman, Rainier P. Soriano (Thirteenth ed.). Philadelphia. ISBN 978-1-4963-9817-8. ↑
8. Explanation: Auscultation is the process of listenening, usually with the aid of a stethoscope, to sounds producedby movement or gas gas or liquid with the body, and is an aid to the diagnosis of abnormalities of the heat, lungs, intestines and other organs according to the characteristic changes in sound pattern caused by different disease processes. Source: Oxford Concise Medical Dictionary. ↑
9. Source: Bickley, Lynn S. (2021). Bates’ guide to physical examination and history taking. Peter G. Szilagyi, Richard M. Hoffman, Rainier P. Soriano (Thirteenth ed.). Philadelphia. ISBN 978-1-4963-9817-8. ↑
10. Source: https://www.ncbi.nlm.nih.gov/medgen/534403# ↑
11. Source: https://www.bhf.org.uk/informationsupport/conditions/heart-murmurs#Heading2 ↑
12. Source: https://stanfordhealthcare.org/medical-conditions/blood-heart-circulation/heart-murmurs/types.html ↑
13. Ibid ↑
14. Sources: (1) “Patient education: Heart murmurs (The Basics)”. UpToDate. 25 March 2022, and (2) heart murmur” at Dorland’s Medical Dictionary ↑
15. 0 Bickley, Lynn S. (2021). Bates’ guide to physical examination and history taking. Peter G. Szilagyi, Richard M. Hoffman, Rainier P. Soriano (Thirteenth ed.). Philadelphia. ISBN 978-1-4963-9817-8 ↑
16. See: “Patient education: Heart murmurs (The Basics)”. UpToDate. 25 March 2022 ↑
17. Source: “continuous murmur” at Dorland’s Medical Dictionary ↑
18. Ibid ↑
19. Ibid ↑
20. Ibid ↑
21. Explanation: In cardiac physiology, the Levine grading scale is a numeric scoring system to characterize the intensity or the loudness of a heart murmur. The name comes from researcher Samuel A. Levine who studied the significance of systolic heart murmurs. ↑
22. See: (1) Orient JM (2010). “Chapter 17: The Heart”. Sapira’s Art & Science of Bedside Diagnosis (4th ed.). Philadelphia: Wolters Kluwers Health. p. 339. ISBN 978-1-60547-411-3, and (2) Freeman AR, Levine SA (1933). “Clinical significance of systolic murmurs: Study of 1000 consecutive “noncardiac” cases”. Ann Intern Med. 6 (11): 1371–1379 ↑
23. Source: https://en.wikipedia.org/wiki/Levine_scale ↑
24. At: https://www.health.harvard.edu/a_to_z/heart-murmur-a-to-z ↑
25. Source: https://www.mayoclinic.org/diseases-conditions/heart-murmurs/symptoms-causes/syc-20373171 ↑
26. At: https://www.bhf.org.uk/informationsupport/conditions/heart-murmurs ↑
27. Source: https://www.bhf.org.uk/informationsupport/conditions/heart-murmurs ↑
28. Ibid ↑
29. See: https://www.nhs.uk/conditions/endocarditis/ © Crown Copyright acknowledged ↑
30. See: https://www.nhs.uk/conditions/pericarditis/ © Crown Copyright acknowledged ↑
31. Source: https://www.healthline.com/health/heart-disease ↑
32. Source: https://www.mayoclinic.org/diseases-conditions/heart-murmurs/diagnosis-treatment/drc-20373175 ↑
33. Source: https://www.heart.org/en/health-topics/heart-murmurs ↑
34. Source: https://www.gosh.nhs.uk/conditions-and-treatments/general-medical-conditions/heart-murmurs-innocent/ ↑
35. Source: https://www.mayoclinic.org/diseases-conditions/heart-murmurs/symptoms-causes/syc-20373171 ↑
36. Source: https://stanfordhealthcare.org/medical-conditions/blood-heart-circulation/heart-murmurs/causes.html ↑
37. Source: https://www.mayoclinic.org/diseases-conditions/heart-murmurs/diagnosis-treatment/drc-20373175 ↑
38. At: https://www.bhf.org.uk/informationsupport/treatments ↑
39. Based on information at: https://www.heart.org/en/health-topics/heart-valve-problems-and-disease/heart-valve-problems-and-causes/heart-murmurs-and-valve-disease ↑