HEART MURMURS AND YOUR CHILD

Definition

By itself, the term heart murmur is not a diagnosis of an illness or disorder, but to understand what it does mean, it's important to know how the heart works.

The heart is divided into four chambers; two are on the left and two are on the right. The blood pumped by the heart is oxygenated by the lungs and then carried through the arteries to the rest of the body. After the oxygen has been used, the blood returns to the heart through the veins and is pumped through the lungs again. The word murmur describes a swishing sound made as the blood flows through the heart's chambers or valves.

A murmur can be heard through a stethoscope between normal heartbeats or in conjunction with them. Because a child's heart is very close to the chest wall, subtle noises can be heard more easily. Sometimes, a pediatrician won't be able to hear a child's heart murmur unless the child is sitting quietly. Heart murmurs are most commonly discovered when the child is between 2 and 4 years old. Some pediatricians think this is because most children have had time to become familiar with their doctor and are more quiet and cooperative during the exam.

Diagnosis

Because of the common misconception that all heart murmurs are serious, it is important for parents to understand which type of murmur their child has, and if it needs further evaluation.

Heart murmurs are rated on a scale from 1 to 6. Grade 1 is barely audible, while grade 6 is very loud. Your child's doctor will also note where in the heart the murmur is, what type of noise it is making (for example, clicking or blowing), and whether it changes when your child moves to different positions. After this initial discovery, your child's doctor may refer her to a pediatric cardiologist if further evaluation is necessary.

Innocent murmurs

The most common type of heart murmur is called functional or innocent. This diagnosis means the murmur is produced by a normal, healthy heart and does not pose a health threat. It can come and go throughout childhood, and will probably go away on its own.

Children with innocent heart murmurs do not require a special diet, restriction of activities, or any other special treatment. A child who is old enough to understand that she has a heart murmur should be assured that she is not different from other children.

Congenital heart defects

Some heart murmurs may indicate a problem with the heart. If your child's doctor suspects something other than an innocent heart murmur, he or she will refer your child to a pediatric cardiologist, who will order or perform additional tests such as a chest X-ray or ECG, also known as an echocardiogram.

About one out of every 100 babies is born with a heart problem, which is called a congenital heart defect. These babies may show signs of their defect as early as the first few days of life, or they may appear completely healthy until later in childhood. Some children won't show any symptoms beyond a heart murmur, while others will have symptoms that could be mistaken for other illnesses or disorders.

"Symptoms of significant heart disease in newborns and infants include rapid breathing, difficulty feeding, blueness in the lips (cyanosis), and failure to thrive," says David Ferry, MD, a pediatric cardiologist at Cedars-Sinai Medical Center in Los Angeles, California. "Symptoms in the child or adolescent may be fatigue or difficulty exercising." Contact your child's doctor if you notice any of these symptoms in your child.

Some genetic factors (such as chromosome abnormalities) and environmental factors (such as exposure to industrial chemicals) cause congenital heart defects, but many children have no known risk factors. Some parents may have more than one child with a heart defect, but in most cases, the heart defect is not considered to be heriditary.

Maternal health plays a role - pregnant women who contract rubella (German measles), have uncontrolled or poorly regulated diabetes, or have PKU (an inborn error of body chemistry called phenylketonuria) have a higher risk of having a baby with a heart defect. Drinking alcohol while pregnant or paternal (father's) use of cocaine also may increase the risk.

Babies with other birth defects or who are born prematurely may also have heart defects.

Common heart defects and their treatment

The most common types of heart defects are usually structural defects, which include holes inside the heart (atrial septal defect or ventricular septal defects) and narrow valves (aortic or pulmonary stenosis).

Septal defects involve the walls that divide the chambers of the heart - these walls are called the septum. A hole may be present in the septum, causing blood to leak into the other chambers, which may make the heart work too hard.

Some holes may be large enough to produce symptoms in addition to a heart murmur, while others are smaller and may close on their own in time. Pediatric cardiologists will help decide if surgery is necessary to repair the hole.

Valve abnormalities are also common. There are four valves (one-way openings) in the heart. These valves keep the blood from flowing backward. Valves that are narrowed or blocked do not permit normal blood flow. Sometimes these valves can be opened without surgery by using balloon catheters, or surgeons may operate on them.