The present invention provides devices and methods for preventing or significantly reducing the risk of thrombus formation. More specifically, the devices and methods of the present invention provide energy to blood flowing within a chamber or vessel to prevent or reduce blood stasis and thereby prevent or significantly reduce the risk of thrombus formation. The present invention is ideally suited for prevention or reduction of risk of blood clot formation in the atria in patients with atrial fibrillation, in blood vessels of patients at risk of clot formation, in areas adjacent to, or on, artificial heart valves or other artificial cardiovascular devices, and the like.