What Is a Heart Murmur? Grades, Causes, and When to Get an Echocardiogram for Heart Murmur

Heart murmurs are not always cause for concern, but this article will explain when to get checked with an echocardiogram.

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Heart murmurs are often detected during routine check-ups, and while they can sound alarming, they aren't always a cause for concern. If you’ve just been diagnosed with a heart murmur and are concerned about what this could mean for you, this guide will explain what a heart murmur is, its potential causes, how they are graded, and when you might need an echocardiogram to investigate the condition. An echocardiogram is a key diagnostic tool used to look inside the heart to assess its health and evaluate any abnormal changes. 

Let’s get right into it!

What is a heart murmur?

To learn what a murmur of the heart is, it is important to first understand how blood flow works.

The heart is a four-chambered muscular organ that constantly pumps blood throughout the body via a network of blood vessels: arteries, which carry oxygenated (oxygen-rich) blood, and veins, which carry deoxygenated (oxygen-poor) blood. 

The timing and direction of blood flow within the heart is controlled by four valves—thin, strong flaps of tissue (known as leaflets or cusps)—located at the entrance of each heart chamber. These valves open and close rhythmically to direct blood to the appropriate channels and prevent backflow, producing two sounds often described as ‘lub-dub’ that you recognise as your heartbeat. A heart murmur (also called a cardiac murmur) is an unusual sound that occurs along with the normal heartbeat sound.

You might be wondering: ‘what does a heart murmur sound like?’ As described by doctors who listen to the heart through a stethoscope, a heart murmur sounds like a whoosh, hum, swish, or rasp. The sound is caused by turbulent (rapid, rough or forceful) blood flow through the valves within the heart.

Is a heart murmur dangerous? - Not all heart murmurs are harmful. Some are common findings regarded as a benign (harmless) or innocent heart murmur, meaning they don't affect your health or require any treatment, while other murmurs can signal a heart problem that requires prompt medical attention. 

It’s important to note that both worrisome and innocent heart murmurs can sound the same through a stethoscope, so distinguishing between them usually necessitates a more thorough physical examination, a medical history review, and diagnostic imaging tests like an echocardiogram.

What are the symptoms of a heart murmur?

What does a heart murmur feel like? - A heart murmur doesn’t produce a feeling or symptom that you would notice, as it is a sound rather than a sensation or disease. But this only applies to innocent heart murmurs. If a heart murmur is due to an underlying heart condition, you might experience symptoms related to that condition.

Here are heart murmur symptoms to look out for:

  • Fatigue and dizziness

  • Fainting spells

  • Chest pain

  • Fast, pounding, or skipping heartbeat

  • Shortness of breath

  • Swelling in the legs, ankles, or abdomen

  • Persistent coughing

  • Cyanosis (a bluish or purple tinge to the skin, fingernails, or lips due to low blood oxygen level)

  • Swollen neck veins

  • Excessive sweating after minimal physical activity or even while at rest

Signs of a heart murmur in babies and young children may also include:

  • Stunted growth

  • Poor appetite

  • Excessive fussiness

  • Rapid or irregular heartbeat

What causes a heart murmur?

Innocent heart murmurs are common in newborns, children, young people, and adults. They come and go, appearing more frequently during certain developmental or life stages.

Even though they aren’t due to heart problems, innocent murmurs result from changes in blood flow within the heart. These changes can be caused by:

  • Pregnancy (a woman’s body makes and pumps 45% more blood during pregnancy).

  • Exercise or any physical activity that raises your heart rate.

  • Fever (a raised body temperature is often associated with an increased heart rate, as the heart pumps more blood and oxygen to help the immune system fight against illness).

  • Growth spurts.

  • Hyperthyroidism (an overactive thyroid gland can increase a person’s heart rate and blood pressure).

  • Untreated high blood pressure.

  • Anaemia (a condition in which there is a shortage of healthy red blood cells to carry oxygen throughout the body, causing the heart to work harder to compensate for insufficient oxygen levels).

Can anxiety cause a heart murmur? - Anxiety triggers the body’s fight-or-flight response, leading to temporary changes such as increased sweating, muscle tension, rapid breathing, and elevated heart rate and blood pressure. These changes can disrupt normal blood flow within the heart and might cause a murmur, though this is usually not a cause for concern.

When babies have worrisome heart murmurs, it is often due to congenital heart defects (CHDs), which are conditions present from birth. Common congenital anomalies include:

  • Septal defects: A hole in the wall between the heart’s chambers. If the hole is between the lower chambers, it’s known as a ventricular septal defect (VSD), and if it’s between the upper chambers, it’s called an atrial septal defect (ASD). 

  • Bicuspid aortic valve: Commonly seen in male infants, it is a condition where one of the heart’s four valves, the aortic valve (which connects the heart to the main blood vessel that carries blood away), develops two flaps of tissue instead of three.

Heart murmur in adults is often caused by problems with one or more of the heart’s four valves: mitral, tricuspid, aortic, and pulmonary. Sometimes, these valves can become narrowed (stenosis) or leak (regurgitation). For example: 

  • Mitral stenosis: The mitral valve starts constricting and doesn’t open properly. 

  • Aortic regurgitation: The aortic valve doesn’t close tightly, allowing blood to leak backwards.

Heart valve diseases don’t develop on their own; they are typically caused by:

  • Calcification (the accumulation of calcium deposits on and around the heart valves).

  • Congenital heart defects.

  • Rheumatic fever (an inflammatory condition resulting from a throat infection which, if left untreated, can spread to the heart valves and cause a rheumatic heart disease).

  • Bacterial endocarditis (an infection of the heart’s inner lining and valves).

Grades of heart murmur

To help determine whether a heart murmur is innocent or worrisome, identify its underlying cause, and plan the most appropriate treatment, all heart murmurs are carefully analysed based on their characteristics, such as their primary location, intensity (loudness), site(s) of radiation or echo, pitch, and timing. 

Heart murmurs are also graded—based on their intensity—on a scale of 1 to 6, with 1 being a faint, barely audible sound and 6 being very loud.

Heart murmur grades

  • Grade 1: A murmur so faint it can only be heard when an experienced clinician listens carefully in a quiet room.

  • Grade 2: A heart murmur that is soft, faint or intermittent, but audible without requiring special effort by the clinician. 

  • Grade 3: A moderately loud, easily audible heart murmur. 

  • Grade 4: A very loud murmur.

  • Grade 5: An extremely loud heart murmur that can be heard with the stethoscope lightly or partially touching the chest.

  • Grade 6: A murmur so loud it can be heard without the stethoscope being in direct contact with the chest.

It’s worth noting that grade 4 heart murmurs and higher are usually accompanied by a thrill—a palpable vibratory sensation. Additionally, the heart murmur grades don't always correlate with the severity of the underlying cause or condition. For instance, a grade 3 heart murmur can be associated with a serious heart condition, while a grade 6 murmur might be due to an innocent cause. However, the type of murmur can be indicative of its severity. For example, systolic heart murmurs (i.e., those that occur when the heart contracts and pumps out blood) are generally harmless, while diastolic murmurs (i.e., those that occur when the heart relaxes and fills with blood) and continuous murmurs (i.e., those that occur throughout the heartbeat) often point to a problem in the heart.

When to worry about a heart murmur

When to worry about a heart murmur in children

Many children have innocent heart murmurs that they eventually outgrow. However, if a murmur is accompanied by symptoms such as poor weight gain, stunted growth, excessive fussiness, difficulty feeding, or bluish skin, it’s important to consult with a paediatrician.

When to worry about a heart murmur in adults

If you develop a heart murmur later in life and are not pregnant, anaemic, or suffering from an overactive thyroid, but you are experiencing symptoms such as shortness of breath, chest pain, or  fainting, it could be a cause for concern.

When to worry about a heart murmur in elderly people

Heart murmurs in older adults can sometimes indicate age-related changes in the heart, such as valve calcification (an excess build-up of calcium deposits on the heart valve). If you’re an older adult and have been diagnosed with a heart murmur, consider getting an echocardiogram to assess the situation.

When to get an echocardiogram for a heart murmur

An echocardiogram, or echo, is a type of ultrasound used to examine the heart. It is a non-invasive, painless, and quick procedure that uses high-frequency sound waves to produce detailed, moving pictures of the heart chambers, valves, and surrounding blood vessels. Since the heart is constantly beating, the echocardiogram offers detailed, dynamic insights into how blood flows through the heart and heart valves.

Do I need an echocardiogram if I have a heart murmur? 

As a gold-standard imaging test, an echocardiogram heart murmur scan is often the first port of call in cases where a doctor suspects a murmur may be due to an abnormality in the heart. Therefore, whether you need one will depend on the nature of the murmur and your symptoms. 

What does an echocardiogram show for a heart murmur?

You might be wondering: ‘Will an echocardiogram show a heart murmur?’ ‘What does a heart murmur look like on an echocardiogram?’ A heart murmur echocardiogram scan doesn’t “show” the murmur, but it does show the structures and functions of the heart that might be causing the murmur. For example, if a murmur is due to a leaky valve, the heart murmur echocardiogram results will show the valve’s abnormal movement and the regurgitation (backward flow) of blood.

It may help:

  • Identify structural heart defects present at birth and those acquired due to ageing, trauma, or lifestyle habits.

  • Assess how well the heart is pumping blood and whether there’s any evidence of heart failure.

  • Show whether the heart’s valves are opening and closing properly and whether there’s any leakage or narrowing.

  • Determine the size and shape of the heart chambers and assess the thickness of the heart muscle.

An echocardiogram for heart murmur scan may be used alongside other tests, such as an electrocardiogram (ECG/EKG), chest X-ray, or cardiac catheterization, to provide a more comprehensive evaluation of the structural or functional changes responsible for the abnormal sound and any associated symptoms.

Book an echocardiogram for heart murmur diagnosis today to address your concerns and get all the answers you need. Scan.com is the UK’s largest imaging network, so you can choose an option that best fits your location, schedule, and budget. We also deliver a complete care package, including pre- and post-scan clinician consultations with our experienced clinician team, referral, and digital access to your report and images quickly, supporting you from finding the right scan and preparing for it to understanding your results.

Not sure if an echocardiogram is right for you? Book a consultation for £50 to speak to a member of our expert clinician team, who’ll review your medical history and offer tailored advice. If after, you decide to book your scan with us, you’ll get a £50 discount on your fee. 

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