Plaque accumulates when cholesterol, platelets and other material in the blood build up around damaged areas of the arteries, according to the American Heart Association. Arteries become hardened, narrowed and prone to blood clots. High blood pressure exacerbates this condition, often resulting in arterial blockages.
Atherosclerosis is a process whereby damaged arteries form scar tissue that hardens and accumulates cholesterol plaque, explains WebMD. High blood pressure, often combined with factors such as high cholesterol, smoking or diabetes, creates microscopic tears in the inner lining of arteries called the endothelium. Cholesterol enters these tears, lodging in the arterial walls, and white blood cells gather at these sites to digest the cholesterol. Scar tissue forms around the damaged area, hardening the artery walls and collecting this accumulated mass of cholesterol and blood cells to form a thickening layer of plaque.
Arteries naturally become harder and lose some of their elasticity over time, a process intensified by uncontrolled blood pressure, states the AHA. The continual accumulation of plaque adds to the hardening and narrowing of the arteries and gradually blocks the flow of blood. These blockages do not necessarily cause symptoms but often cause chest pain (angina), reports WebMD. When cholesterol plaques rupture, breaking off and forming blood clots, they can block an artery completely and cause heart attacks.