A heart murmur is an unusual or extra sound in the heart. The heart is made of four chambers. Blood passes from chamber to chamber via valves which open and close. The typical “lub-dub” sound is the closing of the valves. Some babies have a whoosh sound to their heart. This is called a murmur.
Murmurs are a very common finding in newborns. It is estimated that up to three quarters of newborns have a murmur on examination. In most cases, this is nothing to worry about and will resolve as the child gets older. This is called an innocent murmur.
In a small number of cases, the murmur is a sign of underlying disease. This is called a pathological murmur.
Murmurs are classified into three different types based on when they occur in the heartbeat:
In addition, murmurs are graded based on how loud they are when the doctor listens to them. The grades are from I (very faint) to VI (very loud). Grades I-V can only be heard with a stethoscope, while Grade VI can sometime be heard without a stethoscope. Grade V and VI can sometimes be felt when placing a hand on the heart.
Innocent murmurs usually have no symptoms other than an abnormal sound on examination.
In pathologic murmurs, symptoms other than the murmur itself can include:
In the womb, the baby’s circulation and the mother’s circulation are connected via the placenta. After birth, the baby’s body may take some time to adjust to doing everything on its own. This is the most common cause of innocent murmurs.
Other causes of heart murmurs include:
Some of the risk factors that a baby will have a pathologic murmur include:
Murmurs are a sign of possible heart disease. A doctor will run tests to help determine whether the child’s murmur is innocent or pathologic. In addition to listening with a stethoscope, a doctor may use testing such as:
Treatment is aimed at treating the underlying condition causing the murmur, not the murmur itself.
With innocent murmurs, no treatment is necessary. The doctor usually advises monitoring it.
In pathologic murmurs, treatment can include:
If the heart murmur is pathologic, complications can include any complications associated with the underlying condition.
In many cases, it is not possible to prevent a heart murmur. It is best to strive for a healthy pregnancy where a mother follows her health team’s advice.