The use of mechanical pumps for circulatory support started in the mid-1950s. The evolution of these devices has led to the present-day use of continuous-flow pumps to take over the function of a patient's failing heart. The physiology associated with rotary blood pump use is quite different from normal cardiovascular physiology. Clinicians caring for patients who are supported by rotary blood pumps must have an understanding of the differences in physiology, monitoring methods, and unique complications associated with the use of these pumps.