Atherosclerosis is a process that involves the development of plaques in the inner lining of large and medium sized arteries. Eventually the plaque matures into a structure consisting of 2 main parts: a soft "inner core" that consists of cholesterol, waste products, inflammatory cells and calcium, and a thin outer shell called the "fibrous cap."

As a plaque builds up it can begin to block the flow through an artery. If one of these plaques ruptures or part of the fibrous cap erodes, exposing the inner core, a blood clot can rapidly form around it and block the vessel. If the vessel is a main coronary artery, it can lead to a heart attack.

If the clot blocks a vessel leading to the brain, it can result in a stroke. A stroke may cause permanent damage to that portion of the brain that receives oxygen and nutrients through that vessel. Some of the plaque or clot can also break off and block blood flow in smaller arteries downstream. The result can be temporary or permanent “mini-strokes” (also called Transient Ischemic Attacks or TIAs).

Because high blood pressure forces blood through the arteries at an increased pressure, the resulting damage to the inner wall of the artery can increase the risk of atherosclerosis. In fact, high blood pressure actually makes an individual more susceptible to developing these dangerous plaques.