Your baby’s heart murmur was probably identified at her routine developmental appointment when her doctor listened to her chest and heart with a stethoscope. Understandably, now you are scared and worried. But the truth is that heart murmurs are very common and almost always of no consequence: about 75% of all children have it at some time during their childhood and they are harmless in close to 99% of cases. Most murmurs should not be a cause for concern and won’t affect a child’s health at all.
The term heart murmur refers to a sound of blood flow through your baby’s heart. It is not a disease.
How Your Baby’s Heart Works
Your baby’s 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 (in purple on the image below), and the two upper filling chambers are the atria (in pink on the image below).
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 (like a saloon door). As the valves shut to control the flow of blood through the heart, they make the “lub-dub” sound we recognize as the heartbeat.
Babies’ hearts beat faster than older children and are more likely to produce murmurs as they do so. A newborn’s resting heart rate is about 130 beats per minute, while a child’s is normally around 80 to 100 and an adult’s is 70 to 90.
This is what a heartbeat sounds at 17 weeks of gestation:
This is what a heartbeat sounds like at 6 months of age:
This is what a heartbeat sounds like in adults:
As you probably heard, 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.” When there is a heart murmur, there is an extra sound added to the “lub-dub” making it sound like “lub-shh-dub.” Most of the times, these extra sounds are simply the sound of normal blood flow moving through a normal heart. In these cases, the murmurs are called “innocent.” Other times, a murmur may be a sign of a heart problem.
Diagnosing a Heart Murmur
Your baby’s doctor will listen to your baby’s heart by placing a stethoscope on different areas of her chest. It helps if your baby is quiet when the doctor listens, because some heart murmurs are very soft. It’s not unusual for a heart murmur to be heard for the first time during a routine check-up.
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, your baby’s doctor may refer her to a pediatric cardiologist for further evaluation, including an echocardiogram. An echocardiogram is an ultrasound scan of your baby’s heart, similar to the scans you had during pregnancy. The scan shows your baby’s heart’s structure, function, and blood flow through her heart. It records the motion of the blood through the heart and can measure the direction and speed of blood flow. It is safe for your baby and is easy to carry out.
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.
For clues, your baby’s healthcare professional will try to determine where in the heart the murmur is occurring, when in the heartbeat cycle it happens, what type of noise it is, how loud it is, and whether it changes when your child changes position.
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 your child gets older.
Congenital Heart Defects
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 in which wires are attached painlessly to your daughter’s chest arms and legs), or an echocardiogram.
Just under one baby in a hundred turns out to have something wrong with their heart – either in its structure or in the way it works -so called congenital heart disease (CHD). This makes it a rare problem, fortunately only a third of babies with CHD need any treatment, the rest correct themselves as the baby grows older.