Q. During my yearly checkups, what exactly is my doctor listening for when she moves her stethoscope over my heart?

A. The most common heart problems detected with a stethoscope are conditions that affect one of your four heart valves — usually the aortic valve or the mitral valve. While the causes of unusual heart sounds often end up being harmless, some sounds signal issues that require monitoring and treatment.

A stethoscope amplifies the sounds generated inside your heart — mainly, your heartbeat. The familiar “lub-DUB, lub-DUB” of a normal heartbeat is the sound of your valves snapping shut.

Doctors usually place their stethoscopes in four different places on your chest wall to listen to each valve. In some people, the valve does not open or close properly, either because of a defect present at birth or an acquired defect due to aging, an infection, or other causes. The turbulent blood flowing across the valve can cause a whooshing sound, called a murmur.

Heart murmurs fall into two main categories: benign (also called flow or functional murmurs) and abnormal (which doctors usually refer to as structural murmurs). About one in 10 adults hasa benign heart murmur, which your doctor can hear when blood flows across a normal valve more forcefully than normal. Exercise or anxiety can trigger this increased blood flow, as can third trimester pregnancy, high fever, or anemia. These benign murmurs can come and go and do not require treatment.

But sometimes, a murmur is a signal that a valve isn’t working properly. In adults, the most common cause of a structural murmur is narrowing (stenosis) of the aortic valve or back-flow (regurgitation) of blood because of a leaky aortic or mitral valve.

To evaluate a heart murmur, your doctor may ask you about symptoms such as breathing difficulties or fainting spells. During the exam, she may ask you to do things that create subtle, temporary changes in blood flow through your heart, such as holding your breath, gripping your hands, sitting, squatting, standing up quickly, or lying down.

Often, additional testing is needed to assess the heart valves. These can include an echocardiogram (ultrasound of the heart), an electrocardiogram (which records the heart’s electrical activity), or a chest x-ray. Medication cannot cure a leaky or narrowed valve. Fortunately, most people with structural heart murmurs remain free of symptoms, requiring nothing more than regular checkups and echocardiograms. But people with severe valve disease may need a procedure or surgery to repair or replace their faulty valve.