Should I Worry About a Heart Murmur?
Q. During a recent checkup, my doctor told me I have a heart murmur. Should I be worried?
Dr. Marianne Legato: Most patients are quite alarmed when their doctor tells them they have a heart murmur -- and usually unnecessarily so. A "heart murmur" is the sound a physician hears through her stethoscope. It is caused by rough or turbulent blood flow. This can be due to any one of several things.
One cause is a problem with one of the valves that allow blood to flow from one chamber of the heart to the next without backflow. Guiding blood in the right direction is achieved by an ingenious system of these valves, each of which opens to allow blood to flow forward and then closes to ensure that that blood does not leak backward into the chamber from which it has just come.
In the normal heart, the delicate leaflets of tissue that make up the valve -- as thin as tissue paper -- open and close smoothly and completely -- like swinging doors that guard the entrance to a store. If those leaflets are thickened, as they are in older people or in people who have had some injury to the valve (like rheumatic fever, for example), they do not open completely (or may not close snugly) and the smooth flow of blood is disturbed, creating a unique sound that your doctor learns to interpret. The most expert physicians are able to tell simply by listening which valve is involved, and what is wrong with it.
Another common cause of turbulent blood flow has nothing to do with inadequate or diseased heart valves. Sometimes either the speed of blood flowing through the heart or the volume of blood passing through it is increased. These conditions create turbulence -- a lot like a stream after a heavy rain that races and foams along its course, or a car that races along a road at high speed. These are things that we expect to happen in pregnancy (when blood volume increases) or with fevers (when the speed at which blood flows through our heart increases). Other temporary -- and treatable -- conditions that cause heart murmurs are anemia and hyperthyroidism. Some murmurs are simply "innocent" or "functional"; many young people have soft murmurs that are not of any consequence because they are simply the result of the vigorous beating of their hearts. These are more apparent in thin people.