Heart Murmur: Causes, Symptoms & When to Worry

What Is a Heart Murmur?

A heart murmur is an extra or unusual sound heard during a heartbeat when a doctor listens with a stethoscope. It is caused by turbulent blood flow through or near the heart, creating a whooshing, swishing, or rasping sound distinct from the normal "lub-dub" heartbeat sounds.

To understand heart murmurs, it helps to know how the normal heart sounds are produced. The characteristic "lub-dub" sound of a healthy heartbeat comes from heart valves closing. The first sound ("lub") occurs when the mitral and tricuspid valves close as the ventricles begin to contract. The second sound ("dub") happens when the aortic and pulmonary valves close as the ventricles relax. These sounds are crisp and distinct in a healthy heart.

A heart murmur represents additional sound between, during, or around these normal heart sounds. The turbulence creating this sound can result from blood flowing through narrowed valves, blood leaking backward through valves that don't close properly, blood flowing through abnormal passages in the heart, or simply blood flowing quickly through a structurally normal heart.

The significance of a heart murmur depends entirely on its cause. In many cases, particularly in children, murmurs are completely benign findings that require no treatment and cause no health problems. However, murmurs can also be the first sign of serious heart conditions that need medical attention. This is why proper evaluation by a healthcare provider is important whenever a murmur is detected.

Types of Heart Murmurs

Heart murmurs are broadly classified into two main categories based on their underlying cause and clinical significance. Understanding this distinction is crucial because it determines whether any follow-up or treatment is needed.

Innocent (functional or physiologic) murmurs occur in structurally normal hearts. They are caused by blood flowing through the heart in ways that create audible turbulence without any underlying abnormality. These murmurs are extremely common and completely harmless. They may be heard more prominently during fever, anemia, pregnancy, or exercise – conditions that increase blood flow through the heart.

Abnormal (pathological or organic) murmurs result from structural problems with the heart, most commonly involving the heart valves. These can be present from birth (congenital) or develop later in life (acquired). Abnormal murmurs require further investigation to determine their cause and whether treatment is needed.

What Causes Heart Murmurs?

Heart murmurs are caused by turbulent blood flow. Innocent murmurs result from normal blood flow in a healthy heart, while abnormal murmurs are caused by structural heart problems such as valve stenosis (narrowing), valve regurgitation (leaking), septal defects (holes in heart walls), or other cardiac abnormalities.

The causes of heart murmurs vary significantly between innocent and abnormal types, and understanding these causes helps explain why some murmurs are concerning while others are not. Blood normally flows through the heart in a smooth, laminar pattern. When this flow becomes turbulent – whether due to increased velocity, anatomical abnormalities, or changes in blood viscosity – it creates the sounds we identify as murmurs.

Causes of Innocent Murmurs

Innocent murmurs occur in hearts with completely normal structure and function. They are particularly common in children because their chest walls are thinner and their hearts are closer to the surface, making blood flow sounds easier to hear. Several factors can make innocent murmurs more audible:

• Fever: Increases heart rate and blood flow velocity
• Anemia: Reduces blood viscosity, allowing faster flow and more turbulence
• Pregnancy: Increases blood volume and cardiac output by up to 50%
• Hyperthyroidism: Increases metabolic rate and cardiac output
• Physical exercise: Temporarily increases heart rate and blood flow
• Anxiety or stress: Activates sympathetic nervous system, increasing heart rate
• Growth spurts in children: Rapid growth can cause temporary turbulence

In children, specific types of innocent murmurs have been identified. Still's murmur, the most common, creates a musical or vibratory sound typically heard between ages 2-7. The venous hum, heard in the neck area, results from blood flowing through the jugular veins and disappears when lying down. Pulmonary flow murmurs occur due to blood flow across the pulmonary valve and are common in thin children and adolescents.

Causes of Abnormal Murmurs

Abnormal murmurs indicate structural heart problems that cause turbulent blood flow. These conditions can be present from birth or develop over time due to aging, infection, or other factors. The most common causes include:

Valve stenosis occurs when a heart valve becomes narrowed, restricting blood flow. This forces blood through a smaller opening at higher velocity, creating turbulence. Aortic stenosis, narrowing of the aortic valve, is the most common valve disease in adults over 65. Mitral stenosis, often caused by rheumatic fever, restricts blood flow from the left atrium to left ventricle. Pulmonary stenosis is frequently congenital and varies from mild to severe.

Valve regurgitation (also called insufficiency or incompetence) happens when a valve doesn't close completely, allowing blood to leak backward. Mitral regurgitation is the most common valve disease worldwide. Aortic regurgitation can result from valve damage or aortic root enlargement. Tricuspid regurgitation is often secondary to other heart conditions.

Septal defects are holes in the walls (septa) between heart chambers. Ventricular septal defect (VSD) is the most common congenital heart defect, creating a hole between the left and right ventricles. Atrial septal defect (ASD) is a hole between the upper chambers that often goes undetected until adulthood.

What Are the Symptoms of a Heart Murmur?

Innocent heart murmurs cause no symptoms – the murmur itself is only detected during physical examination. Abnormal murmurs may be accompanied by shortness of breath, chest pain, dizziness, fainting, fatigue, rapid heartbeat, swelling in legs or feet, and blue-tinged skin. In infants, poor feeding and failure to thrive are warning signs.

An important point to understand is that a heart murmur itself is a physical finding, not a symptom. People cannot feel or sense their own heart murmurs – they are only detected when a healthcare provider listens to the heart with a stethoscope. The symptoms that matter are those that accompany the underlying condition causing the murmur.

Innocent murmurs are completely asymptomatic. A child or adult with an innocent murmur feels entirely normal and has no limitations whatsoever. The murmur is simply an incidental finding on examination. This is why innocent murmurs are also called "functional" murmurs – the heart functions perfectly normally.

When heart murmurs are caused by underlying cardiac problems, the symptoms depend on the specific condition and its severity. Mild valve disease may cause no symptoms at all, while more severe disease can significantly impact quality of life. Symptoms typically develop gradually as the condition progresses.

Common Symptoms in Adults

Adults with significant valve disease or other cardiac conditions causing murmurs may experience a range of symptoms that reflect the heart's reduced ability to pump blood effectively:

• Shortness of breath: Often first noticed during exercise, later occurring with minimal activity or at rest. May worsen when lying flat (orthopnea)
• Fatigue and weakness: Reduced cardiac output means less oxygen delivery to muscles and organs
• Chest pain or discomfort: May occur with exertion, particularly in aortic stenosis
• Dizziness or lightheadedness: Results from reduced blood flow to the brain
• Fainting (syncope): A serious symptom requiring urgent evaluation, particularly with aortic stenosis
• Palpitations: Awareness of rapid, irregular, or forceful heartbeats
• Swelling: Fluid retention in legs, ankles, feet, or abdomen indicates heart failure
• Rapid weight gain: From fluid retention, may be several pounds in a few days

Warning Signs in Children and Infants

While most murmurs in children are innocent, certain symptoms suggest a more serious underlying condition and warrant prompt medical evaluation:

• Poor feeding: Infants tire easily during feeding, take a long time to finish bottles
• Failure to thrive: Poor weight gain despite adequate feeding
• Blue or gray skin coloring: Especially around lips, fingertips, or during crying (cyanosis)
• Rapid breathing: Breathing faster than normal, especially at rest or during feeding
• Excessive sweating: Particularly during feeding or activity
• Easily fatigued: Tires more quickly than peers during activity
• Delayed growth and development: Not meeting expected milestones

How Are Heart Murmurs Diagnosed?

Heart murmurs are first detected through cardiac auscultation (listening with a stethoscope). Doctors assess the murmur's timing, location, intensity (graded 1-6), quality, and radiation. Echocardiogram is the gold standard test for determining the cause, showing heart valve structure and blood flow. Additional tests may include ECG, chest X-ray, or cardiac MRI.

The diagnostic process for heart murmurs begins with the physical examination and may progress to various imaging and testing modalities depending on initial findings. A skilled clinician can often distinguish innocent from potentially pathological murmurs based on auscultation alone, though confirmatory testing is frequently recommended.

Physical Examination and Auscultation

When listening to the heart, healthcare providers assess several characteristics of the murmur that provide clues to its cause. This assessment requires careful technique and considerable experience. The examination is typically performed with the patient in multiple positions (lying down, sitting, standing) as some murmurs change with position.

Timing refers to when the murmur occurs in the cardiac cycle. Systolic murmurs occur during ventricular contraction (between the first and second heart sounds). Diastolic murmurs occur during ventricular relaxation (between the second and first heart sounds). Continuous murmurs occur throughout both phases. Systolic murmurs are more common and can be innocent or abnormal, while diastolic murmurs are almost always pathological.

Location indicates where the murmur is loudest on the chest wall. Different valve conditions produce murmurs that are loudest at specific locations: aortic valve sounds at the right upper sternum, pulmonic valve at the left upper sternum, tricuspid valve at the left lower sternum, and mitral valve at the left side near the apex of the heart.

Intensity is graded on the Levine scale from 1 to 6:

Echocardiogram: The Gold Standard

An echocardiogram, often simply called an "echo," uses ultrasound waves to create detailed images of the heart's structures and blood flow. This non-invasive, painless test is the most important diagnostic tool for evaluating heart murmurs because it directly visualizes the valves and other heart structures.

The echocardiogram provides critical information including the size and shape of heart chambers, thickness and movement of heart walls, structure and function of all four heart valves, direction and velocity of blood flow (using Doppler), presence of any holes or abnormal connections, and estimates of pressures within the heart. This comprehensive assessment definitively determines whether a murmur is innocent or caused by structural heart disease, and if abnormal, quantifies its severity.

Additional Diagnostic Tests

Depending on the initial evaluation, additional tests may be recommended to complete the diagnostic picture:

• Electrocardiogram (ECG/EKG): Records the heart's electrical activity, detecting rhythm abnormalities, chamber enlargement, or evidence of previous heart damage
• Chest X-ray: Shows heart size and shape, lung congestion, and calcium deposits on valves
• Transesophageal echocardiogram (TEE): Ultrasound probe placed in the esophagus provides clearer images, especially of mitral and aortic valves
• Cardiac MRI: Detailed imaging particularly useful for complex congenital heart disease or when echo results are inconclusive
• Exercise stress testing: Evaluates heart function during physical exertion, revealing symptoms or changes not present at rest
• Cardiac catheterization: Invasive test measuring pressures directly within heart chambers and coronary arteries

How Are Heart Murmurs Treated?

Innocent heart murmurs require no treatment. Abnormal murmurs are treated based on their underlying cause: watchful waiting for mild cases, medications (beta-blockers, ACE inhibitors, diuretics, anticoagulants) for moderate disease, and surgical intervention (valve repair, valve replacement, or transcatheter procedures) for severe cases.

The approach to treating heart murmurs depends entirely on the underlying cause and its severity. Treatment decisions are based on whether the murmur represents innocent blood flow or structural heart disease, the specific type and severity of any valve abnormality, the presence and severity of symptoms, and the overall health status of the patient.

Management of Innocent Murmurs

Innocent murmurs require absolutely no treatment because they do not indicate any heart problem. Children and adults with innocent murmurs can participate fully in all activities, including competitive sports, with no restrictions whatsoever. The only "management" needed is reassurance that the murmur is harmless.

However, it's important that innocent murmurs be properly identified through appropriate evaluation. If there is any uncertainty about whether a murmur is innocent, an echocardiogram should be performed to confirm the diagnosis. Once confirmed as innocent, no follow-up testing is typically needed unless new symptoms develop or the murmur changes in character.

Watchful Waiting

Many people with mild valve disease may not need immediate treatment but benefit from regular monitoring. This approach, called watchful waiting or surveillance, is appropriate when valve abnormality is mild, no symptoms are present, heart function is preserved, and the condition is stable. Monitoring typically includes regular check-ups with a cardiologist, periodic echocardiograms to assess progression, lifestyle modifications to protect heart health, and prompt attention to any new symptoms.

Medication Therapy

While medications cannot repair damaged valves, they can help manage symptoms, protect heart function, and slow disease progression. The specific medications depend on the type of valve disease and individual patient factors:

• Diuretics: Reduce fluid retention and relieve symptoms of congestion
• ACE inhibitors or ARBs: Lower blood pressure and reduce strain on the heart in regurgitant valve disease
• Beta-blockers: Slow heart rate and reduce blood pressure, helpful in various conditions
• Anticoagulants: Prevent blood clots in patients with atrial fibrillation or mechanical heart valves
• Antiarrhythmics: Control abnormal heart rhythms that may develop with valve disease
• Vasodilators: Reduce the heart's workload in certain types of valve regurgitation

Surgical and Interventional Procedures

When valve disease becomes severe or significantly symptomatic, surgical intervention may be necessary. The decision to proceed with surgery depends on the type and severity of valve disease, symptom severity and progression, heart function measurements, patient age and overall health, and risk assessment for surgery.

Valve repair is preferred when possible because it preserves the patient's own valve tissue and typically doesn't require lifelong anticoagulation. Repair techniques include annuloplasty (tightening the valve ring), leaflet repair, and removal of calcium deposits. The mitral valve is most commonly repaired, though some aortic valve conditions can also be addressed with repair.

Valve replacement involves removing the diseased valve and implanting a prosthetic valve. Mechanical valves are extremely durable but require lifelong anticoagulation with warfarin. Biological (tissue) valves come from pig, cow, or human donors and don't require long-term anticoagulation, but may wear out and need replacement after 10-20 years. The choice between mechanical and biological valves depends on patient age, lifestyle, ability to take anticoagulation, and patient preferences.

Transcatheter procedures offer less invasive alternatives to open-heart surgery. Transcatheter aortic valve replacement (TAVR) has revolutionized treatment for aortic stenosis, particularly in older or higher-risk patients. MitraClip and similar devices can treat mitral regurgitation through a catheter. Balloon valvuloplasty can open narrowed valves in certain situations.

Can You Live a Normal Life with a Heart Murmur?

Yes, most people with heart murmurs live completely normal lives. Those with innocent murmurs have no restrictions whatsoever. Even many people with mild abnormal murmurs can participate in all normal activities. Only those with significant valve disease may need activity modifications, though modern treatments allow most patients to maintain good quality of life.

Living with a heart murmur depends entirely on whether it's innocent or abnormal, and if abnormal, how severe the underlying condition is. The vast majority of people with heart murmurs face no limitations whatsoever in their daily lives, work, or recreational activities.

People with innocent murmurs can and should live completely normal lives with no restrictions. This includes participation in all sports and physical activities, normal pregnancy and childbirth, any type of career including physically demanding jobs, and all travel including air travel. No special precautions are needed, and no follow-up testing is required unless the murmur characteristics change or symptoms develop.

Those with mild valve disease can often also lead essentially normal lives, though some monitoring is typically recommended. Regular follow-up appointments ensure any progression is detected early. Most people with mild disease can exercise, work, and travel normally. Pregnancy may require additional monitoring but is often possible. Healthy lifestyle choices become especially important to protect heart health.

People with moderate to severe valve disease may face more limitations, though modern treatments have dramatically improved outcomes. Some may need to limit strenuous physical activity. Symptoms should be reported promptly to healthcare providers. Medication adherence is crucial for those on prescribed treatments. With appropriate treatment, including surgery when indicated, most people can maintain good quality of life.

When Should You Worry About a Heart Murmur?

Worry about a heart murmur if it's accompanied by symptoms such as shortness of breath, chest pain, dizziness, fainting, rapid heartbeat, leg swelling, or unusual fatigue. In children, poor feeding, failure to gain weight, or blue-tinged skin require urgent evaluation. Any newly detected murmur in adults should be investigated with echocardiography.

Understanding when to be concerned about a heart murmur helps ensure appropriate medical attention while avoiding unnecessary worry. The murmur itself is not what matters – it's the underlying cause and any associated symptoms that determine significance.

Seek medical evaluation promptly in the following situations: new symptoms develop such as breathlessness, chest discomfort, or palpitations; an existing murmur becomes louder or changes in character; dizziness, lightheadedness, or fainting occurs; unusual fatigue limits normal activities; swelling develops in legs, feet, or abdomen; exercise tolerance decreases noticeably; and in children, if growth or development seems delayed.

Seek emergency care immediately for severe chest pain, sudden severe shortness of breath, fainting or loss of consciousness, blue discoloration of lips or fingertips, and rapid irregular heartbeat with feeling faint.

In adults, a newly detected murmur warrants investigation even without symptoms because adults are more likely than children to have pathological murmurs, valve disease often progresses silently for years, early detection allows for monitoring and timely intervention, and some conditions benefit from preventive treatment. An echocardiogram provides definitive answers about whether further action is needed.