The heart is a strong muscle about the size of your fist that pumps blood around the body. It sits inside the chest and is protected by the ribcage. The heart has four different areas, or chambers. These chambers are connected to each other by valves that control how much blood enters each chamber at any one time. The valves open and shut with every beat. As the valves shut to control the flow of blood through the heart, they make the sound you recognize as your heartbeat.
Depending on a person's age, the heart beats about 60 to 120 times every minute. Each heartbeat is really two separate sounds: lub-dub, lub-dub. Your heart goes "lub" with the closing of the valves that control blood flow from the upper chambers to the lower chambers. Then, as the valves controlling blood going out of the heart close, your heart goes "dub."
A heart murmur is a whooshing sound between the beats that a doctor hears through a stethoscope. The whoosh is an extra noise that the blood makes as it flows through the heart. Doctors usually discover murmurs during regular checkups or when kids see the doctor because they're sick.
More than half of all children have a heart murmur at some time in their lives; and most heart murmurs don't mean anything is wrong. Doctors may call these "innocent," "functional" or "normal" murmurs. They are caused by blood rushing through the valves in a normal heart and are nothing to worry about.
A normal murmur can get louder when the blood flows faster through the heart, like when kids have a fever or run around. That's because an increase in body temperature or activity makes the heart pump more blood. When your temperature goes down, the murmur may get quieter or even disappear. Some innocent murmurs are caused by an illness that is not related to the heart but can cause the blood to flow faster than normal, creating murmur. This may include fever, anemia and hyperthyroidism.
Even though most murmurs do not mean anything is wrong, sometimes a heart problem can cause a murmur. These types of murmurs are called abnormal. Abnormal heart murmurs can be caused by congenital heart defects (conditions you are born with) or acquired defects (caused by another condition).
Congenital heart defects are present at birth and are the most common cause of murmurs in younger children. Congenital heart defects may include heart valve problems such as narrow valves that reduce blood flow, leaky valves that don’t close correctly, septal defects—also known as holes in the heart—and defects in the veins and arteries that carry the blood to and from the heart. Sometimes heart muscle cells enlarge causing the wall of the ventricles to thicken, blocking blood flow out or affecting the mitral valve, causing blood to leak backward through the valve.
Acquired heart defects occur after birth and develop as a result of another condition. Those conditions may include damage and scar tissue from a heart attack, high blood pressure, heart failure and calcium deposits. Some valve diseases are due to infection and past rheumatic fever with heart valve inflammation due to a bacterial streptococcus infection. With present day screening for strep infections and the appropriate use of antibiotics, this risk factor has decreased significantly.
Other risk factors for heart valve abnormalities include atherosclerotic heart disease, heart attack, aortic aneurysm and connective tissue disorders, such as lupus and Marfan syndrome. Each condition affects the valves in a different way, causing them to malfunction and develop the physical finding of a heart murmur.
For children with an innocent heart murmur, the only way you will know they have a murmur is if your pediatrician hears it during a routine examination. That’s because there are no signs or symptoms; this type of murmur is not caused by a heart defect or heart disease, thus the name “innocent.”
Children with either congenital or acquired murmurs will have signs or symptoms related to the type of heart defect that is causing their murmur. The following is a list of the most common symptoms:
- Skin has a grey or blue look, especially around lips, gums and tongue
- Fingertips may be bluish or grey
- Swollen hands, abdomen, feet or ankles and swelling around the eyes
- Can’t keep up and tires more easily than other children
- Gets out of breath sooner than other children
- Gets sweaty with exercise faster than other children
- Sudden weight gain due to swelling
- Enlarged liver
- Enlarged veins in the neck
- A chronic cough
Some valvular diseases are present at birth, but take a lifetime to develop symptoms. For example, the aortic valve is supposed to have three leaflets that come together; some people are born with a valve that has only two leaflets (bicuspid). Over time, a two-leafed valve may be more prone to calcification and narrowing. Symptoms may only be seen later in life.