Parents might worry if they're told that their child has a heart murmur. But heart murmurs are very common, and many kids are found to have one at some point. Most murmurs are not a cause for concern and won't affect a child's health at all.
The term heart murmur isn't a diagnosis of an illness or disorder. To better understand what it does mean, it helps to know a bit about the heart.
How the Heart Works
The heart has four chambers and four valves (which work like one-way doors). The two lower pumping chambers of the heart are called the ventricles, and the two upper filling chambers are the atria (plural of atrium).
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"lub-dub" sound we recognize as the heartbeat.
Depending on a person's age, the heart beats about 60 to 120 times every minute. Each heartbeat is really two separate sounds. The 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, the heart goes "dub."
Using a stethoscope, a doctor examines the heart by listening to the sounds it makes. A heart murmur describes an extra sound heard in addition to the "lub-dub." Sometimes these extra sounds are simply the sound of normal blood flow moving through a normal heart. Other times, a murmur may be a sign of a heart problem.
Diagnosing a Heart Murmur
Doctors listen to the heart by putting a stethoscope on different areas of the chest. It helps if kids are quiet as the doctor listens, because some heart murmurs are very soft. It's not unusual for a murmur to be noticed during a routine checkup, even if none was heard before.
Heart murmurs are rated on a scale from 1 to 6 based on how loud they are. Grade 1 is very soft, whereas grade 6 is very loud. If a murmur is found, the doctor may refer a child to a pediatric cardiologist for further evaluation.
What's an Innocent Heart Murmur?
The most common type of heart murmur is called functional or innocent. An innocent heart murmur is the sound of blood moving through a normal, healthy heart in a normal way. Just as you might hear air moving through an air duct or water flowing through a pipe, doctors can hear blood moving through the heart even when there's no heart problem.
An innocent heart murmur can come and go throughout childhood. Kids with these murmurs don't need a special diet, restriction of activities, or any other special treatment. Those old enough to understand that they have a heart murmur should be reassured that they aren't any different from other kids.
Most innocent murmurs will go away on their own as a child gets older.
Some murmurs can indicate a problem with the heart. In these cases, doctors will have a child see a pediatric cardiologist. The cardiologist will likely order such tests as a chest X-ray, an EKG (an electrocardiogram), or an echocardiogram. An echocardiogram, or "echo," is an ultrasound picture of the heart structures (chambers, walls, and valves). It records the motion of the blood through the heart and can measure the direction and speed of blood flow.
About 1 out of every 100 babies is born with a structural heart problem, or congenital heart defect. These babies may show signs of the defect as early as the first few days of life or they may appear completely healthy until later in childhood. Some kids won't have any symptoms beyond a heart murmur, while others will have symptoms that could be mistaken for other illnesses or disorders.
Signs of a significant heart defect in newborns and infants can include:
have trouble exercising or doing physical activity
have chest pain
Call your doctor if your child has any of these symptoms.
Pregnant women have a higher risk of having a baby with a heart defect if they get rubella (German measles), have poorly controlled diabetes, or have PKU (phenylketonuria, a genetic error of the body's metabolism).
Common Heart Defects
Several kinds of heart problems can cause heart murmurs, including:
Septal defects, which involve the walls (or septum) between the upper or lower chambers of the heart. A hole in the septum can let blood flow through it into the heart's other chambers. This extra blood flow may cause a murmur. It can also make the heart work too hard or become enlarged. Bigger holes can cause symptoms besides a heart murmur; smaller ones may eventually close on their own.
Valve abnormalities, caused by heart valves that are narrow, too small, too thick, or otherwise abnormal. These valves don't allow smooth blood flow across them. Sometimes, they can allow backflow of blood within the heart. Either problem will cause a murmur. Outflow tract obstruction might be caused by extra tissue or heart muscle that blocks the smooth flow of blood through the heart.
Heart muscle disorders(cardiomyopathy), which can make the heart muscle abnormally thick or weak, hurting its ability to pump blood to the body normally.
Your doctor and a pediatric cardiologist can determine if the murmur is innocent (which means your child is perfectly healthy) or if there is a specific heart problem. If there is a problem, the pediatric cardiologist will know how to best take care of it.