Bma Illustrated Medical Dictionary

atherosclerosisAccumulation of choles-
teroland other fatty substances (lipids)
in the walls of arteries, causing them to
narrow. Atherosclerosis can affect arter-
ies in any area of the body and is a
major cause of stroke, heart attack (see
myocardial infarction), and poor circula-
tion in the legs. The arteries become
narrowed when fatty substances, such
as cholesterol, that are carried in the
blood accumulate on the inside lining
of the arteries and form yellow deposits
called atheroma. These deposits restrict
blood flow through the arteries. In addi-
tion, the muscle layer of the artery wall
becomes thickened, narrowing the artery
even more. Platelets (tiny blood cells
responsible for clotting) may collect in
clumps on the surface of the deposits
and initiate the formation of blood
clots. A large clot may completely block
the artery, resulting in the organ it sup-
plies being deprived of oxygen.
There are usually no symptoms in the
early stages of atherosclerosis. Later,
symptoms are caused by reduced or
total absence of a blood supply to the
organs supplied by the affected arteries.
If the coronary arteries, which supply
the heart muscle, are partially blocked,
symptoms may include the chest pain
of angina. If there is complete blockage
in a coronary artery, a sudden, often fatal,
heart attack may occur. Many strokes
are a result of atherosclerosis in the
arteries that supply blood to the brain.
If atherosclerosis affects the leg arter-
ies, the 1st symptom may be cramping
pain when walking due to poor blood
flow to the leg muscles. If the condition

is associated with an inherited lipid

disorder (see hyperlipidaemias), fatty

deposits may develop on tendons or

under the skin in visible lumps.

The risk of developing atherosclerosis

is determined largely by the level of

cholesterol in the bloodstream, which

depends on dietary and genetic factors.

Athersclerosis is most common in West-

ern countries, where most people eat a

diet high in fat. Some disorders such as

diabetes mellitus can be associated with

a high cholesterol level regardless of diet.

Blood flow through an artery can be

investigated by angiographyor Doppler

ultrasound scanning.

The best treatment for atherosclerosis

is to prevent it from progressing by fol-

lowing a healthy lifestyle. This includes

eating a low-fat diet, not smoking, exer-

cising regularly, and maintaining the

recommended weight for height. These

measures lead to a lower-than-average

risk of developing significant athero-

sclerosis. People found to have high

blood cholesterol but who are other-

wise in good health will be advised to

adopt a low-fat diet. They may also be

given drugs that decrease blood choles-

terol levels (see lipid-lowering drugs).

For people who have had a heart attack,

research has shown that there may be a

benefit in lowering blood cholesterol

levels, even if the level is within the

average range for healthy people.

People who have atherosclerosis and

are experiencing symptoms of the con-

dition may be prescribed a drug such as

aspirinto reduce the risk of blood clots

forming on the damaged artery lining.

ATHEROSCLEROSIS ATHEROSCLEROSIS

A

ATHEROSCLEROSIS

EARLY ATHEROSCLEROSIS ADVANCED ATHEROSCLEROSIS

Fatty

deposit

Muscle layer

of artery

Fat

globule

Fatty

deposit

Thickened

muscle layer

New

muscle cell

Narrowed

artery