Functional murmurs are an important consideration in the precordial examination of an infant or child.

In the adult, hyperdynamic circulation of the blood may also produce a functional murmur, such in anemia or thyrotoxicosis.

Functional murmurs are benign (an "innocent murmur").

In many cases the referral of paediatric patients to paediatric cardiologist are subjective and more than 60% of the referrals are due to an innocent or functional murmur.

A functional murmur or "physiologic murmur" is a heart murmur that is primarily due to physiologic conditions outside the heart, as opposed to structural defects in the heart itself.

Its location, timing, association with severe anemia, and resolution upon correction of anemia, are consistent mechanistically with a functional murmur arising from high volume flow dynamics in the left main coronary artery, which has almost entirely diastolic flow.