Atherosclerosis

Atherosclerosis is a disease affecting the arterial blood vessel and it is commonly referred to as a "hardening" or "furring" of the arteries. It is caused by the formation of multiple plaques within the arteries. Theses plaques begin to form when a vessel receives tiny injuries, usually at a point of branching. In turn these plaques gradually thicken and harden with fibrous material, cells, and other deposits, restricting the lumen (opening) of the vessel and reducing blood flow to the tissues, a condition known as ischemia.

Pathologically, the athermanous plaque is divided into three discrete components:

The atheroma ("lump of porridge", from Athera,) is the nodular accumulation of a soft, flaky, yellowish material at the center of large plaques, composed of macrophages nearest the lumen of the artery, underlying areas of cholesterol crystals, and possibly also calcification at the outer base of older/more advanced lesions. The following terms are comparable, yet diverse, in both spelling and meaning, and can be effortlessly confused: arteriosclerosis, arteriolosclerosis and atherosclerosis.

Arteriosclerosis, is a all-purpose term describing any hardening (and loss of elasticity) of medium or large arteries ("Arterio" meaning artery and "sclerosis" meaning hardening), arteriolosclerosis is arteriosclerosis mainly affecting the arterioles (small arteries), atherosclerosis is a hardening of an artery in particular due to an atheromatous plaque ("athero" means "porridge"). Consequently, atherosclerosis is a type of arteriosclerosis. Arteriosclerosis ("hardening of the artery") results from a deposition of tough, rigid collagen inside the vessel wall and around the atheroma. This increases the stiffness, decreases the elasticity of the artery wall. Arteriolosclerosis (hardening of small arteries, the arterioles) is the product of collagen deposition, but also muscle wall thickening and deposition of protein ("hyaline"). Calcification, occasionally even ossification (formation of complete bone tissue) occurs within the deepest and oldest layers of the sclerosed vessel wall.

Atherosclerosis causes two main problems. First, the atheromatous plaques, though long compensated for by artery magnification, ultimately lead to plaque ruptures and stenosis (narrowing) of the artery and, consequently, an insufficient blood supply to the organ it feeds. On the other hand, if the compensating artery magnification development is excessive, then a net aneurysm results. Also, an aneurysm is an arterial wall weakened by atherosclerosis, malformation, injury, or other causes may balloon out.

These impediments are chronic, slowly progressing and snowballing. Most normally, soft plaque suddenly ruptures, causing the formation of a thrombus that will rapidly slow or stop blood flow, e.g. 5 minutes, leading to death of the tissues fed by the artery. This calamitous event is called an infarction. One of the most frequent predictable scenarios is called coronary thrombosis of a coronary artery causing myocardial infarction (a heart attack). Another frequent scenario in very advanced disease is claudication