Mechanical cardiovascular assist devices must be properly designed to avoid damage to the blood they contact. The factors that affect the hemocompatibility of a cardiovascular assist device include three major non-physiological components - the material, fluid flow paths, and flow related stresses, - as well as the device interaction with the native vasculature. Furthermore, the interaction of the device with the blood is not static. Foreign surfaces activate blood components including platelets, leukocytes and the coagulation cascade. Thrombus formation on the surface of the device can alter...