Graphic illustration of the development of atherosclerosis in three steps. Atherosclerosis is a form of arteriosclerosis which involves variable combinations of intima transformations. The intima is the innermost layer of a blood vessel. The development of atherosclerosis is facilitated by a high blood fat level (hypercholesterolemia). The cholesterol (fat), which is transported in the form of LDL (picture), then diffuse into the vascular walls (cross-section 2) and accumulates (cross-section 3). The lumen is reduced which hinders the bloodflow. Now there is an increased risk of formation of thrombi, which could occlude this or other vessels. That would cause an infarct.