A heart murmur is a vibration in blood movement that causes a characteristic sound, heard by the physician when listening with a stethoscope. Murmurs are caused by disorders in function of the valves that control blood flow into and around the heart. Some murmurs are of no consequence. Others may be a warning sign of serious problems.
HOW DO HEART VALVES FUNCTION?
The heart has four chambers — two small upper chambers (atria) and two large lower chambers (ventricles). Each ventricle has a one-way inlet valve and a one-way outlet valve. They open to allow blood to move forward and close to prevent back-flow of blood.
WHAT HAPPENS WHEN A VALVE FUNCTIONS?
If a valve fails to close properly — called incompetence, insufficiency, or regurgitation — some blood leaks back into the prior chamber with each beat. If it fails to open properly — called stenosis — not enough blood moves through the abnormally narrow opening. Either problem can force the heart to work much harder and seriously interfere with its ability to pump blood.
WHAT VALVE PROBLEMS CAUSE HEART MURMURS?
Mitral valve prolapse causes the valve leaflets to bulge into the left atrium during ventricular contraction, sometimes allowing leakage of small amounts of blood. Mitral valve regurgitation is leakage back through the mitral valve each time the left ventricle contracts. Mitral valve stenosis is a narrowing of the mitral valve opening that increases resistance to blood flow from the atrium to the left ventricle.
Tricuspid valve stenosis is a narrowing of the tricuspid valve that increases resistance to blood flow from the right atrium to the right ventricle. Tricuspid valve regurgitation is leakage of the tricuspid valve each time the right ventricle contracts.
Aortic valve stenosis is a narrowing of the valve opening that increases resistance to blood flow from the left ventricle to the aorta. Aortic valve regurgitation is leakage of the aortic valve each time the left ventricle relaxes.
WHAT ARE THE SYMPTOMS OTHER THAN MURMURS?
Some people have none. Depending on the type and severity of problem, others may have chest pain, palpitations, migraines, fatigue, dizziness, fainting, and shortness of breath. When the left ventricle must pump more blood, it gradually enlarges to increase the force of each heartbeat. This may cause chronic (congestive) heart failure. When the left atrium enlarges to accommodate the extra blood leaking back from the ventricle, it may beat rapidly in an irregular disorganized pattern (atrial fibrillation), which further reduces the heart’s pumping efficiency and increases the risk of blood clots that may cause a stroke.
WHAT CAUSES VALVE PROBLEMS?
Until the advent of antibiotics for strep throat, rheumatic fever used to be the most common cause. Today in the United States, they are more commonly caused by such problems as a birth defect, a heart attack, or calcification of the valves.
BEYOND THE MURMUR, HOW ARE VALVE PROBLEMS DIAGNOSED?
An electrocardiogram (ECG) and chest X-ray can show left ventricle enlargement. Echocardiography, an imaging technique that uses ultrasound, can show the severity of the problem. Sometimes cardiac catheterization is necessary to determine the extent and characteristics of the blockage.
HOW ARE HEART VALVE PROBLEMS TREATED?
Mild valve problems may not need therapy. Sometimes drugs can slow the heart rate, reduce blood pressure in the lungs, and help control palpitations,fibrillation, and other symptoms. (Many people with heart valve problems are advised to take preventive antibiotics before any dental or surgical procedure to reduce the risk of a heart valve infection.) If drug therapy doesn’t reduce the symptoms satisfactorily, surgical valve repair or replacement may be needed.