What to Know About Still's Murmur

Medically Reviewed by Poonam Sachdev on November 02, 2022
4 min read

Still's murmur was first described in a small section of the pediatrician Dr. George Frederick Still's 1909 book Common Disorders and Diseases of Childhood. He described it as a small sound he wanted to bring attention to. Dr. Still described it as musical, but not indicative of heart pathology or alarming signs. He compared it to a “twanging” piece of tense string music that seemingly does not occur due to any disease of the heart. 

In that case, then, what exactly is this murmur, and why is it significant?

Marked by a low-pitched, musical sound, Still's murmur is produced by the blood flowing through the heart. Despite its unusual sound, it is seemingly not related to a problem of the heart or other health issues. It is most commonly observed in children aged 3 to 6. During a physical exam, a pediatrician can easily detect this incidental heart murmur. Usually, though, the murmur will completely disappear prior to adolescence

When blood flows through the heart of a child, the sound now described as Still's murmur is generated. Medical providers cannot currently pinpoint the cause of the murmur, though some have hypothesized that the sound is caused by:

  • False tendons in the left ventricle. These create a vibrating noise that accompanies blood flow.
  • The chordae (strong thin cords of the heart connected to the tricuspid valve) caught in the blood flow of the right ventricle through the lower right chamber of the heart
  • Increased blood flow turbulence within the heart that may be a result of low red blood cell counts or anemia

Currently, though, no one truly knows what causes a Still's murmur. Ultrasounds of kids' hearts that produce this murmur have been studied, and they have been compared to those of kids who are murmur-free. No one has identified a physical difference. Fortunately, it is obvious that this murmur is not caused by any major heart defects. The most likely explanation is that younger kids have healthy, elastic hearts that cause a ringing sound when the blood flows through them at a certain speed. This sound can be compared to blowing your breath over the top of a soda bottle.

A musical, low-pitched vibration is the signature of Still's murmur. Kids who lay on their backs facing upward may generate the loudest murmurs, which can be heard by medical providers with the aid of a stethoscope. Many kids have a Still's murmur, though it usually goes away by the time they reach adulthood. 

A medical doctor will not attempt to treat the murmur because it in no way threatens a kid's health. Almost 72% of all children will have a heart murmur at some stage in life, and Still's murmurs are the most common nonconsequential heart murmurs observed in kids.

A soft vibration is the main symptom of someone with a Still's murmur. It is often compared to the musical sound of the string instrument called an Aeolian harp, which is manipulated by the wind. You should not be able to hear the murmur of a child, but a medical provider can listen to it with a stethoscope. The murmur will also be louder when a kid lies down with their face pointing up. The sound is softer when they stand or sit. The murmur can fluctuate, coming or going at different times. When a child is excited or ill, the Stills' murmur might be louder. The murmur is not a signal of (nor does it cause) other health conditions.

Once your pediatrician has detected Still's murmur, they will monitor the condition. They will determine if it changes with movement like lying down or standing up. They will monitor whether the murmur is heard in a single place or radiates to other places. There is no radiation in the case of a Still's murmur. 

The doctor will have to pinpoint an exact location. A Still's murmur is located mainly in the center of the chest and anterior to the rib cage in the lower left sternum. When the murmur occurs is also important when it comes to diagnosis. Whether it happens when the heart contracts or rests will make it a diastolic or systolic murmur. A Still's murmur is mid-systolic. A Stills's murmur is soft-sounding, so the intensity will be monitored. The quality and pitch should remain musical, low, and similar to the sound of blowing. 

Since it does not indicate a medical problem with the heart, there is no required treatment for Still's murmur. An affected child should have a totally normal life without limitations or restrictions. Still's murmur has no complications because there is physically nothing wrong with the heart. It usually will disappear during puberty. In the rare situation in which it does not, it still is of no consequence because the murmur is found in an otherwise healthy heart.