Heart Murmur: Sounds, Types, and When to See a Doctor

Medically Reviewed By Meredith Goodwin, MD, FAAFP
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A heart murmur is an extra heart sound. Doctors can hear heart murmur sounds with a stethoscope. Hearts murmurs can occur in both adults and children. Several conditions can cause a heart murmur. Most people with heart murmurs have no outward signs or symptoms. If a doctor hears abnormal heart sounds, cardiac diagnostic and imaging tests can help find the underlying cause. Some heart murmur causes require treatment to prevent complications.

This article goes over the types of heart murmurs and how doctors diagnose and treat them.

What is a heart murmur and what does it sound like?

A heart murmur is an irregular noise due to vibrations caused by turbulent blood flow happening as the heart beats.

Heart murmurs can sound like swishes, whooshes, blowing, or clicking. The sounds come as blood moves through the heart’s chambers, valves, and arteries.

Normal heart sounds are in a familiar lub-dub pattern. Heart murmurs are abnormal sounds in addition to the lub and the dub.

One way doctors characterize heart murmurs is in terms of when the sounds occur during the cardiac cycle. Heart murmurs may be systolic, diastolic, or continuous.

  • Systolic murmur: This type of heart murmur happens when the heart muscle contracts. Doctors hear this after the lub and before the dub. Systolic murmurs tend to be loud, include click sounds, and last briefly.
  • Diastolic murmur: Diastolic murmurs occur when the heart muscle relaxes between beats. Doctors hear this murmur after the dub and before the next lub. Diastolic murmurs tend to be quieter, low-pitched, include a knocking sound, and last longer.  
  • Continuous heart murmurs: Doctors can hear the sounds of these murmurs throughout a heartbeat cycle — that is, during both the lub and the dub. The sounds continuous heart murmurs make depend on the underlying heart condition.

Heart murmurs can vary in loudness and duration. Doctors grade them on their intensity or loudness. They can be so faint that they are hard to hear with a stethoscope. This is a grade 1 murmur. The highest grade, grade 6, is audible without the stethoscope in contact with the chest.

What are the different types of heart murmur?

The two main types of heart murmur are innocent heart murmur and pathologic murmur.

Innocent heart murmur

Innocent heart murmurs are normal, functional, or physiological murmurs. They typically occur in children and may disappear and reappear as the child ages. By adulthood, they are usually gone.

Innocent heart murmurs are harmless, with no need for medication or lifestyle changes. Innocent murmurs in children include Still’s murmur and venous hum.

Innocent heart murmurs can also affect adults during pregnancy and activities that promote an increase in blood flow.

Pathologic murmur

Pathologic murmurs are abnormal or noninnocent murmurs. Less than 1% of pediatric heart murmurs fall into this category. In children, heart murmurs can be a sign of congenital heart disease (heart disease due to heart problem present at birth).

In adults, a new heart murmur may point to heart valve disease.

What are the symptoms of a heart murmur?

Heart murmurs are often symptoms of other problems. Often, a doctor or nurse notices a heart murmur during a routine physical exam. If your doctor hears a heart murmur, they may refer you to a cardiologist for follow-up care.

Seek emergency medical care (call 911) for symptoms that could indicate a serious problem with the heart or heart valves, including:

Heart murmurs in babies

Heart murmurs in babies may occur with these serious symptoms:

  • bluish tint to lips and fingernails
  • little to no weight gain compared to infants of same age and gender
  • rapid breathing
  • tiring easily, even while nursing

Seek prompt medical care (or call 911) if you notice rapid breathing or a bluish tint in your child.

What causes a heart murmur?

The sound of a heart murmur is due to the turbulent flow of blood through the heart or arteries. 

Possible causes of heart murmurs include:

  • congenital heart defects, including atrial septal defect, patent ductus arteriosus (cardiac shunt), and valve defects
  • endocarditis, which is an infection of the heart
  • heart valve disease — either regurgitation or stenosis, which is the most common cause of abnormal heart murmurs in adults
  • rheumatic fever, which is a complication of an untreated streptococcus bacterial infection such as strep throat

Innocent heart murmurs in children and adults can result from anything that temporarily increases blood flow. This includes: 

What are the risk factors for a heart murmur?

A number of factors increase the risk of developing a heart murmur. However, not all people with risk factors will get a heart murmur. Risk factors for heart murmur include:

  • congenital heart defects
  • family history of heart defects
  • high blood pressure
  • hyperthyroidism
  • history of endocarditis or rheumatic fever
  • uncontrolled diabetes or rubella infection during pregnancy
  • misuse of alcohol or drugs
  • certain medications during pregnancy

Reducing the risk of heart murmur

You may be able to lower the risk of heart murmur by keeping your heart healthy. This includes:

  • controlling conditions such as high cholesterol, high blood pressure, and diabetes
  • getting regular physical exercise
  • eating a healthy diet
  • maintaining good oral hygiene to reduce risk of bacteria entering the bloodstream and affecting your heart valves
  • quitting or not smoking
  • reducing alcohol intake

Contact your doctor to discuss your specific risk for heart murmur. Keep a schedule of regular checkups to monitor your health for any potential signs of heart murmur. 

How do doctors diagnose the cause of a heart murmur? 

To diagnose a heart murmur, your doctor will listen to your heart to determine:

  • where the heart murmur occurs in your heart  
  • whether the heart murmur can be heard in your back or your neck 
  • how loud the heart murmur is
  • whether the heart murmur is low-, medium- or high-pitched 
  • whether the sound of the heart murmur changes with body movement
  • when the heart murmur occurs
  • how long the heart murmur lasts 

If necessary, your doctor may order the following tests to diagnose a heart murmur: 

  • Chest X-ray: This imaging exam could show an enlarged heart that may cause a heart murmur. 
  • Echocardiogram: This is the main test to diagnose the cause of a heart murmur. It creates images of the heart’s structure and function using ultrasound waves. The images may show abnormal heart valves or heart defects that could cause a heart murmur. 
  • Electrocardiogram (ECG): This test records the electrical signals that make your heart beat using probes on your chest. It may show a disruption in heart rhythm that could lead to a heart murmur. 
  • Cardiac catheterization: This is a catheter-based procedure. It involves inserting a catheter into a blood vessel in the arm or leg. The doctor injects dye through the catheter to your heart. The dye will highlight the blood flow through your blood vessels, heart, and heart valves. It can show whether there is a disruption that could result in a heart murmur. 

How is a heart murmur treated?

Innocent heart murmurs do not require treatment. Pathologic heart murmurs may require treatment of the underlying condition. Treatment may be necessary if the murmur affects the heart’s ability to deliver enough blood and oxygen to the rest of your body. 

Treatment options depend on the underlying condition causing the heart murmur. Your doctor may recommend medications, catheter-based procedures, or surgery.

What are the potential complications of a heart murmur?

Innocent heart murmurs in children tend to disappear with time. A pathologic heart murmur itself does not necessarily lead to complications. However, the underlying causes can cause complications. The complications will vary with the cause. 

Summary

Most heart murmurs are harmless extra heart sounds. They can occur in both adults and children and can be normal.

Sometimes, a heart murmur is a sign of an underlying heart condition. If this is the case, treatment will depend on the cause. In children, the cause is often congenital heart disease. In adults, heart valve disease is the most common cause. 

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Medical Reviewer: Meredith Goodwin, MD, FAAFP
Last Review Date: 2022 Feb 28
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