Narrowing or blockage in the arteries is most often caused by atherosclerosis, also called hardening of the arteries. Although it is commonly thought of as a heart disease, atherosclerosis can affect arteries anywhere in the body, including the legs and the brain. It is a gradual process in which cholesterol and other fatty deposits called plaque build up on the artery walls. These plaques act as barriers that limit blood flow through the arteries to tissues and organs. Other barriers to adequate blood flow include clots or plaques that break away from the blood vessel wall and become lodged in an artery.

When a blood clot, plaque or scar tissue causes an artery to become narrow or completely blocked, blood circulation is limited and the organs and tissues supplied by that artery do not recieve enough oxygen.

What is Atherectomy? (ath"er-EK'to-me)

Atherectomy is a new procedure that removes the fatty deposits that sometimes block coronary arteries. A tiny rotating knife inside a catheter is moved to the arterial obstruction. A balloon is inflated to position the knife precisely on the fatty deposit. Then the knife's power is turned on and it gently shaves the fatty deposit off the wall of the artery. The shavings are collected in the catheter and removed when it is withdrawn from the body.

In a healthy blood vessel, the inner lining of the arteries, known as the endothelium, constricts and dilates with blood flow. Smoking damages the endothelium, making arteries prone to spasms and deposits of diffuse plaque that diminish their ability to dilate properly. This condition is known as atherosclerosis, often called "hardening of the arteries." Atherosclerosis is a gradual process in which cholesterol and scar tissue build up, forming a substance called plaque that clogs the blood vessels and makes them less elastic.