Is that little murmur a cause for worry?

The first time Julie Farkas listened to her son's heartbeat when he was about 4 years old, she heard a garbled noise through the doctor's stethoscope. She listened to her second son's heart. This time she heard a clean, clear, classic lub-dub.

The difference: Farkas's first son has a heart murmur caused by a faulty heart valve. The valve to his aorta has two leaflets instead of the usual three, marring the valve's mechanics.

The lub-dub sound in a healthy heart is the closing of valves, after blood passes through them. "These are the two normal sounds a doctor hears," said Nieca Goldberg, a cardiologist and medical director of the Women's Heart Program at New York University. "If there are extra sounds, those are heart murmurs. The sounds are like a rumbling or swishing or a harsh sound like a machine."

The workings of a heart are simple and exact. Blood flows into the two upper chambers of the heart called the atria. Once the chambers are full, the mitral and tricuspid valves open to allow the blood to move to the lower chambers, the ventricles. Then the valves shut to prevent the blood from returning. As the ventricles contracts, blood is sent on to the rest of the body and lungs.

A murmur means the system maybe be leaking. More than half of American children will have a murmur at some point, according to the Mayo Clinic, but most of those are what doctors call "innocent" murmurs that vanish as a child ages. Adult murmurs are less common, according to heart experts, and may require regular monitoring to make sure they do not turn into something more significant that could threaten the health of the heart.

An example of an innocent heart murmur is one that appears when a woman is pregnant. "Then you are hearing an increase in blood [flowing] across the valves instead of just the valve closing sound," said Jannet Lewis, a cardiologist who is director of noninvasive cardiology at George Washington University Medical Center.

Leaky valves occur for several reasons. The valve leaflets may thicken over time through calcification, making the whole apparatus stiff and less flexible. Stenosis causes a valve's opening to narrow, impeding the flow of blood. Valves can also become floppy, letting them "prolapse" or blow back into the adjoining chamber, causing blood to regurgitate back, too.

There are also several reasons some people develop heart valve problems. In some cases, a person is born with a malformation, as occurred with Farkas's son, who is now 16. The American Heart Association estimates almost 14 people out of 1,000 have a two-leaflet, or bicuspid, aortic valve, like Farkas's son. In cases of congenital heart valve disease, doctors will monitor it with a stethoscope, and an echocardiogram, or sometimes with a chest X-ray or an electrocardiogram (EKG).

"When we are talking about young people with congenital heart disease, it could be a hole in the heart between the chambers," Goldberg said. "Or other conditions or a valve problem. We take an echocardiogram, which takes 15 minutes, has no radiation and doesn't hurt."

The first time Farkas looked at an echocardiogram of her son's bicuspid aortic valve, the cardiologist and technician had to point out the problem so she could see "the leakiness with each opening and closing of the valve," Farkas said. "It broke my heart to see that my child's heart was less than perfect - to see that bicuspid valve working away, leaking just a bit with each beat. But, at the same time I was relieved that, though not perfect, that valve was really working just fine."

Sometimes everyday bacteria and germs, which cause one illness, can then cause valve damage. An example is untreated strep throat that turns into rheumatic fever and compromises the aortic or mitral valve. However, the use of antibiotics has mostly wiped out the disease in the United States. Endocarditis is an infection of the lining of the heart that can also inflame and damage the valves. Heart attacks, high blood pressure and plaque in arteries also can cause a valve to malfunction.

Finally, there is aging. "When you are younger your valves are fine and pliable," said Lewis. "As we get older, though not with everyone, the valves get thicker, especially the aortic valve. There can be calcification.''

Or, as Mary C. Corretti, associate professor of medicine and director of the Adult Echocardiography Lab at Johns Hopkins School of Medicine, put it, valves sag in some older people. "If your tissues are getting wrinkly, your organs are, too," she said. " Valves become incompetent or narrowed and stenotic, unable to open freely with each heart beat."

When a heart murmur becomes more significant, it can begin to affect the heart in negative ways as it tries to adapt. The heart can grow larger, and its walls thicken as it tries to compensate for leaky valves and the backward flow of blood at certain moments in the pumping cycle . The stress on the heart can cause symptoms similar to a heart attack but at a more gradual rate of onset. "Someone could have shortness of breath, fatigue and chest pains similar to coronary angina," Corretti said.

No medicine can cure a heart murmur caused by a failing or impaired valve. And depending on the extent of the valve disease or malfunction, heart surgery may be warranted. A faulty valve requires close monitoring with exams by a physician and periodic echocardiograms. Doctors says that avoiding smoking and controlling such cardiac risk factors as hypertension, diabetes and high-fat diets may partially help decrease the degenerative changes seen in aortic valves.

The good news is that surgical repair of malfunctioning valves is now quite successful. "The most common valve that requires surgery is the mitral valve," said GWU's Lewis. "Ten years ago, the standard was replacement; now there is a push toward repairing," which tends to lead to fewer issues than replacement with an artificial or biologic valve. "When you put a prosthetic valve in an individual, it is never as good as the valve you were born with," Lewis said.

Because heart valve surgery is a major open-heart procedure, some doctors are also trying an investigational, less invasive method that uses specialized clips, inserted through cardiac catheters, to mend or replace faulty valves. A recent report in the New England Journal of Medicine suggested that the procedure had promise for certain patients, though there were serious complications.

For years, people with murmurs were told to take antibiotics before going to the dentist as a precautionary measure against infection that could affect the heart. Just recently the AHA modified its recommendations about antibiotics: Not everyone with a heart murmur needs to take them, just certain groups at high risk for endocarditis, including those with artificial heart valves or a history of the condition.

As for Farkas's son, his cardiologist checks him out each year, and so far so good. He plays baseball on his high school team, runs, snowboards, and plays basketball and tennis. "The leaky valve hasn't slowed him at all because it's so minimally leaky at this point," Farkas said. "Aerobic exercise is absolutely fine. We keep an eye on his cholesterol. Maybe he'll be 50, 60 or 70 when he needs to have the valve replaced. Or maybe not at all."

Hambleton is a freelance writer and documentary filmmaker based in Chevy Chase.