Heart Murmur, Atherosclerosis, & Heart Failure A heart murmur is a sound caused by blood flowing through a child's heart or through blood vessels entering or leaving the heart. More that 50 percent of all people will be diagnosed with a heart murmur sometime in their lives. When a child's doctor or nurse practitioner detects a heart murmur, this causes many parents quite a bit of anxiety, especially if they have relatives with heart disease. Luckily, in most children a heart murmur does not mean that there is something wrong with the heart. In fact, only one in 100 children who have a heart murmur will actu