What causes a heart murmur?
Many different things can cause heart murmurs. Many heart murmurs are caused by problems with the heart valves. Some murmurs are caused by conditions such as anemia or hyperthyroidism.
A person may have a heart murmur, but not be sick. Your doctor may call this an "innocent" or "functional" murmur. This means that, even though your doctor hears a murmur, it is just caused by blood flowing through a normal heart. These noises are commonly heard in children because their hearts are very close to their chest walls. Many innocent murmurs become hard to hear as children grow older, and most usually go away on their own. Pregnant women also sometimes have innocent heart murmurs because the body makes extra blood during pregnancy.
Heart Murmurs in Pedatric Patients: When Do You Refer? by ME McConnell, M.D., SB Adkins III, M.D., and DW. Hannon, M.D. (American Family Physician August 01, 1999, http://www.aafp.org/afp/990800ap/558.html)
Written by familydoctor.org editorial staff