When a heart murmur is detected during routine physical exam, a careful review of the child's appearance and history often provides clues about the murmur's significance.

The classical innocent murmur is the vibratory systolic murmur referred to as Still's murmur. It is soft and of low frequency with a somewhat musical quality, like plucking a string or rubber band. This murmur is of short duration and occurs between the two heart sounds (mid-systole) and is often referred to as "physiologic", or "not significant." Other innocent murmurs are soft, quiet and "blowing" in character. Innocent murmurs often come and go. Also they may disappear if the child sits up or lies down.

Once a murmur is discovered, (provided it's not a classical Still's murmur), observation of the child is important, along with noting vital signs. Is the color of mucous membranes and nailbeds pink or dusky (cyanotic)? Is exercise intolerance present? By history, have there been syncopal episodes or palpitations? All these findings suggest an organic murmur.

There is one acquired lesion which is usually asymptomatic in adolescents and can cause sudden, unexpected death: idopathic hypertrophic sub-aortic stenosis. In this condition, the left ventricular muscle becomes overdeveloped at the point the aorta takes off, thus reducing the outflow of blood. This is the classical lesion seen in male athletes who die unexpectedly during a sports event. It is rarely diagnosed prior to severe symptoms or death.

Organic murmurs are usually louder, occur during a heart sound and are always present. They are usually due to congenital heart disease, but may occur as a sequelae of rheumatic fever. If the murmurs is loud enough, one can feel a vibration if the palm is held over the chest; this is called a "thrill."

Another important technique when assessing a heart murmur is to take the blood pressure in both arms and at least one leg. In coarctation (narrowing) or the aorta, the B.P. in the legs will be lower than in the right arm. An adult size cuff is needed for the leg or a falsely high reading could result.

COMMENT : School nurse practitioners can learn to identify with confidence a classical Still's murmur, the musical, innocent murmur heard in so many children. With a little guided practice with one who has this skill, the sound can be fixed in the mind and never forgotten, thus avoiding unnecessary and expensive (to say nothing of anxiety producing) visits to the cardiologist.

Answer: One of the characteristics of innocent murmurs is that they are often "here today, gone tomorrow." If you are sure that you are hearing a functional or innocent murmur, I suggest you not tell the parent, or even make a note in the child's health record. (You are not expected to list all normal findings on the health record.) Since these murmurs occur at some time or another in 50-70% of all children, you would be over referring.