Classification of Heart Murmurs

Heart murmurs can be classified according to their intensity, tone, or location. In any case, they are usually harmless, although it is advisable to monitor them.
Classification of Heart Murmurs
María Vijande

Reviewed and approved by the pharmacist María Vijande.

Written by María Vijande

Last update: 27 May, 2022

Turbulence in the blood flow as it passes through the heart and large vessels cause vibrations. This in turn causes heart murmurs. In other words, they are sounds that appear during the heartbeat cycle that produce turbulent blood flow in or near the heart. People use stethoscopes to hear heart murmurs.

In addition, you can be born with it, or it can happen at any point in life. If you are born with them, they are called congenital heart murmurs. Above all, it needs to be made clear that murmurs are not a disease. However, they have to be controlled because they can encourage an undiagnosed heart problem.

Characteristics of heart murmurs

A heart.
There are different classifications of heart murmurs.

Characteristics of murmurs must be specified according to their intensity and sound frequency, as well as location in the chest and location in the  cardiac cycle  – if they occur during systole or diastole.

Furthermore, the volume of blood responsible for turbulent blood flow or the tension gradient that causes said turbulence determines the intensity of the murmur.

It’s important to know that the degree of the murmur is not necessarily related to the severity of the cardiac injury.

How to classify heart murmurs?

The most frequently-used classification system was first introduced in 1933 by Levine. He relied on intensity, a term explained above, to be able to classify this cardiac disorder. According to Levine, there are 6 different degrees of heart murmurs depending on their intensity:

  • 1st grade: barely audible. Listening to several cardiac cycles of the patient may be the only way to hear them.
  • 2nd grade: these are soft, but audible.
  • 3rd grade: these are moderate, and palpable vibrations in the chest wall from the passage of blood.
  • 4th grade: these are intense murmurs that are accompanied by a thrill.
  • 5th grade: these are very intense murmurs. They can even be heard by barely touching the chest with the edge of the stethoscope.
  • 6th grade: a stethoscope isn’t needed to hear these murmurs because they’re so intense.

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Other classifications of heart murmurs

A plastic heart.
Whether they occur during systole or diastole also influences murmurs.

Apart from classifying heart murmurs according to their intensity, they can also be grouped based on other characteristics. We can classify them as diastolic or systolic if we take duration into account.

Based on form, they can be constant, increasing, decreasing or a combination of the latter two. As for its location, this refers to the place where the murmur is most intense. Therefore, there are 6 auscultation points on the anterior side of the chest to identify a murmur:

  • In the second intercostal space on the right hand side
  • From the second to the fifth intercostal space on the left hand side
  • In the fifth intercostal space in the left mid-clavicular line

Additionally, murmurs can be classified based on their irradiation. This characteristic refers to where the murmur radiates. It usually goes in the same direction as the blood flow. Finally, depending on its tone, it can be low or high. And quality is a special characteristic of breathing. Meaning it can be musical, blowing, or running, among others.


Some pills.
Treatment will depend on the underlying cause of the murmur.

Heart murmurs are usually harmless, so they usually don’t need treating. Therefore, follow-up tests are sometimes required to make sure they don’t cause an undiagnosed heart disorder.

If treatment is needed, it will be aimed at the cause of the murmur.

For example, if functional murmurs are caused by fever or hyperthyroidism, they will disappear once doctors treat the condition.

Sometimes medication alone isn’t enough to treat the causes of heart murmurs. Sometimes surgery is required. Depending on the condition, your doctor may recommend one of these options to treat a damaged or punctured valve:

If you think you have heart murmurs, seek medical attention immediately. Your doctor will assess the problem and determine how to treat it.


All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Tamariz-Martel Moreno, R. (2008). Los soplos cardíacos en la infancia. Pediatria Integral.
  • Díaz, H. S., Danglot-Banck, C., & Gómez, M. G. (2002). Soplos cardíacos patológicos en los niños. Revista Mexicana de Pediatria.
  • Ruiz-Berdejo Iznardi, C. (2015). Soplo sistólico inocente: importancia diagnóstica. Cardiología Pediátrica y Cardiopatías Congénitas Del Niño y Del Adolescente.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.