Arteriosclerosis

Arteriosclerosis literally means "hardening of the arteries." As people age, their blood vessel walls naturally grow a bit stiffer and harder, with less flexibility. A common complication of arteriosclerosis is called atherosclerosis. In this condition, plaques (hardened masses composed of lipids, dead cells, fibrous tissue, and platelets) collect in the arteries. If a plaque grows large enough, it can block the flow of blood through the artery. If this blockage is severe, it can lead to stroke. A stroke occurs when an artery in the brain becomes blocked, depriving an area of the brain of oxygen. Similarly, a heart attack occurs when a blocked coronary artery deprives the heart muscle of oxygen. Damage to either the brain or heart occurs when areas of oxygen-deprived tissue die. A severe complication of atherosclerosis occurs when a piece of the plaque breaks off and migrates through the artery to other sites. This bit of circulating plaque is called an embolism. An embolism causes damage by blocking blood flow at its destination, resulting in oxygen-deprived tissue and tissue death.

Since atherosclerosis causes strokes and heart attacks, it is considered one of the leading causes of illness and death in the United States. Arteriosclerosis has been linked to high blood cholesterol levels, lack of exercise, and smoking. Cholesterol is a substance that is similar to fat and is found in fatty foods. Although a diet low in cholesterol and fat can reduce the risk of atherosclerosis, some people have a genetic predisposition to high cholesterol levels. Even on normal or low fat diets, these individuals still have high cholesterol (hypercholesterolemia), and therefore a high risk of developing atherosclerosis. Researchers are currently working on ways to help people with hypercholesteremia lower their cholesterol levels. For now, lowering cholesterol is achieved through diet and some drug therapies. In the future, it is hoped that a bioengineered gene that makes a cholesterol-neutralizing protein can be implanted into hypercholesteremia patients.