How to Know if a Heart Murmur Is Dangerous

How to Know if a Heart Murmur Is Dangerous

Some experts believe that as many as 10% of adults and 45% of children in the United States have heart murmurs. Others think the numbers may be much higher, since heart murmurs can come and go without being detected.

But because a murmur can signal problems with the way blood flows through your heart, identifying the underlying cause of the abnormal heart sound is essential.

Leading New York cardiologist and founder of Madison Avenue Cardiovascular in Midtown Manhattan Dr. Mark L. Meyer explains the basics of heart murmurs and what they might mean about your heart health.

What is a heart murmur?

Ordinarily, your physician hears a “lub-dub” sound when listening to your heart with a stethoscope. But when you have a heart murmur, the sound is better described as a whooshing or swishing noise.

Heart murmurs can be harmless and may not require treatment. These “innocent” heart murmurs often occur during:

But a heart murmur sometimes signals an underlying condition that may require ongoing monitoring, medication, or even surgery. Thus, Dr. Meyer notes that any heart murmur should be evaluated to determine its cause.

What causes heart murmurs?

Heart murmurs occur when blood flows abnormally across your heart valves, which may be due to a variety of underlying conditions, including:

Valvular heart disease

Valvular heart disease is the most common cause of heart murmurs. It occurs when heart valves don't open or close properly, disrupting blood flow and creating a murmur.

Congenital heart defects

Some people are born with structural abnormalities in the heart that can cause murmurs. For instance, a septal defect (hole in the heart) is a common congenital abnormality that may or may not require surgical repair.

Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy occurs when the heart muscle enlarges, thickens, or stiffens, making it harder for blood to flow.

Rheumatic fever

This is a complication of untreated strep throat that can cause damage to the heart valves and lead to murmurs.


Endocarditis is an infection of the heart lining and valves that can cause murmurs.


Low levels of red blood cells (anemia) can cause the heart to work harder to pump blood, resulting in a murmur.


Hyperthyroidism, due to an overactive thyroid gland, can cause heart murmurs, anxiety, and a rapid heartbeat.

What are the symptoms of a heart murmur?

Heart murmurs may be asymptomatic and are often discovered during a routine medical exam. But some underlying heart problems that can lead to murmurs may cause symptoms such as:

During your initial evaluation, Dr. Meyer completes a physical exam and detailed review of your symptoms and medical history. Initial diagnostic studies typically include an in-office EKG, echocardiogram, and blood work to further evaluate your heart function.  

Once he’s identified the underlying cause of your heart murmur, Dr. Meyer develops a comprehensive treatment strategy to protect your heart health.  

Schedule a visit with Dr. Meyer at Madison Avenue Cardiovascular today by calling our office or requesting an appointment online.

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