Functional Cardiac Murmurs
Functional murmurs (also called physiologic murmurs) can occur in the absence of valvular pathology. An example would be an aortic systolic ejection murmur caused by a high cardiac output state. Very high flow velocities in the aorta can lead to turbulent flow, which will cause murmurs during the ejection phase of the cardiac cycle. Examples of this include high cardiac outputs in trained athletes and high output states during anemia. Anemia, by reducing blood viscosity, can cause turbulence and murmurs. Pregnancy, which increases resting cardiac output, can cause physiologic ejection murmurs during rest, which will further increase in intensity during exercise as cardiac output increases.