Heart Murmurs – Explaining Those Extra Sounds

The heart is arguably one of the most important organs in the body. It never stops working, and all of the organs and tissues in the body depend on that steady work to deliver necessary oxygen for life.

When the heart is examined with a stethoscope, the person listening is paying attention to the sound of the beats – are they occurring in a regular pattern? Are there extra noises between the  beats? Commonly, the heart sounds are described as “Lub-dub” noises and are simple and predictable. It can take a long time to become comfortable with listening to hearts, especially in young pediatric patients whose hearts beat very rapidly. When I work with medical students in my clinic, it is my goal for them to listen to the hearts of patients of as many different ages as possible. I want these students to become familiar with what “normal” hearts sound like, no matter how rapidly the heart is beating. Once “normal” is established and becomes routine and comfortable to the ear, it is much easier to identify any “abnormal” sounds. 

Heart murmurs are extra noises between the “Lub-dub” sounds of the heart.  They are caused when blood flow becomes turbulent as it flows through the heart and surrounding structures, causing it to be heard more distinctly. It can be a fearful experience for parents when a doctor hears a heart murmur in their child – especially if those parents have no knowledge of what a heart murmur is. Parents often equate any exam findings of the heart with something bad, but heart murmurs in children are actually very common and do not always indicate a problem with the heart itself. 

When discussing murmurs, I often tell parents that there are two very different types of murmurs – innocent heart murmurs which cause no issues, and pathologic heart murmurs which are cause for concern. In order to help determine which type of murmur we are hearing, we listen to the timing of the murmur, how loud it is, and how long it lasts. The good news is these two types of murmurs usually sound very different and further testing is often not needed. Sometimes, however, the sounds are not completely clear. 

It is important to make the distinction between innocent and pathologic heart murmurs. Innocent murmurs are common and harmless. They become louder or more prominent when the child is excited or ill (particularly with fevers). They are not related to underlying heart problems and require no intervention or restrictions in activity. Often these murmurs become harder to hear as children grow older. 

In contrast, pathologic murmurs are a result of a problem with the heart. Thankfully, these are much more rare than innocent murmurs, but they need evaluation and management by a specialist. They may require surgery to correct the problem so the heart can function properly. Pathologic murmurs are loud and harsh. They can occur because of abnormal connections (holes) between the heart chambers, abnormal connections between the large blood vessels that come from the heart, or from defects in heart valves. 

If there is concern for a pathological murmur on exam, further evaluation is needed. This is done by a Pediatric Cardiologist (doctor who specializes in the heart), and sometimes with an echocardiogram and/or electrocardiogram.

• Echocardiogram (Echo): this is an ultrasound of the heart. It allows for visualizing the structures and function of the heart to make sure it is pumping properly. These images will show any abnormal connections within the heart or associated blood vessels, as well as make sure all four chambers of the heart are working appropriately. 

• Electrocardiogram (EKG or ECG): this records the electrical signal produced by the heart to check for abnormalities in heart rhythm and function. 

The results of these tests along with a thorough examination by the Pediatric Cardiologist will determine the proper course of treatment for the child. 

Final thoughts

Hearing heart murmurs is a skill learned over time and with exposure to hearts of all ages and disease states. Pediatricians become very adept at listening carefully – often through bouts of screaming when the exam involves a toddler – for any unusual noises or additions to the expected “Lub-dub” noises of a normal heart that is beating quickly. I make it a point to always tell parents when an innocent murmur is present, so that they are aware that it is there but not of concern. Reassurance is a big part of pediatrics, and the presence of an innocent heart murmur is no exception.