Heart Murmur: Definition, Causes, Symptoms & Treatment

Instructor: Danielle Haak

Danielle has a PhD in Natural Resource Sciences and a MSc in Biological Sciences

A heart murmur is an abnormal sound due to turbulent blood flow through the heart. Murmurs can be innocent (harmless) or abnormal (potentially harmful). In this lesson we will learn the causes, symptoms, and treatments for murmurs.

What is a Heart Murmur?

You've probably heard your heart beat through a stethoscope. Even if you haven't used one, it's likely that a doctor has used a stethoscope to listen to your heart during a checkup. When we listen to the heart, the steady rhythm we are hearing is the sound of the valves opening and closing as the heart pumps blood throughout the body. Sometimes there is an additional 'whooshing' sound that forms due to turbulent blood flow through the heart. This extra sound is called a heart murmur. Some are harmless and some are indicative of a more serious condition.

The sound a heart makes can help diagnose the cause of a heart murmur.
heart sounds image

Causes of Heart Murmurs

What causes this extra whooshing sound? It depends on the type of heart murmur present. Innocent heart murmurs are due to increased blood flow, and these are usually harmless and don't require treatment. Conditions like fever, high blood pressure, overactive thyroid gland, anemia, pregnancy, and periods of rapid growth in teenagers can all cause increased heart rate which can cause a heart murmur.

However, not all heart murmurs are harmless. Abnormal heart murmurs develop due to an irregularity in the heart that can be serious and cause health problems. A number of heart valve conditions may be problematic.

Abnormalities of the heart valves can cause heart murmurs.
heart valve diagram

Here is a list of a few:

  • Aortic sclerosis: the aortic valve thickens
  • Aortic or mitral regurgitation: blood flows backwards in the heart if the valves don't close all the way
  • Aortic or mitral valve stenosis: valves become narrow due to age or infection
  • Mitral valve prolapse: the valve fails to close properly

Stenosis involves the narrowing of valves.
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Congenital heart defects, such as irregular valves or holes in the wall of the heart, can cause abnormal heart murmurs and are the most common cause of murmurs in children. The general term used to describe the thickening of valves is called valve calcification. Heart murmurs can also be caused by an infection of the inner lining of the heart, called endocarditis.

Symptoms of Heart Murmurs

Innocent heart murmurs may not have any symptoms, but abnormal heart murmurs can cause a number of different symptoms. These can include:

  • Chest pains
  • Shortness of breath
  • Passing out/fainting
  • Bluish tint to the fingertips or lips
  • Swelling
  • Sudden weight gain
  • Coughing
  • Enlarged liver
  • Enlarged neck veins
  • Poor appetite
  • Failure to grow (in children)
  • Heavy sweating without exertion

Symptoms may help diagnose what type of abnormality is causing the heart murmur.

Treating Heart Murmurs

Innocent heart murmurs usually don't require any treatment. If the underlying cause of an abnormal heart murmur is known and is treatable, like an infection, it can often be treated and the murmur will disappear. Additional treatment options include the use of diuretics, medications, and surgery.

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