atherosclerosis Accumulation of
and 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
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
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
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
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
to reduce the risk of blood clots
forming on the damaged artery lining.
previous page 55 BMA Illustrated Medical Dictionary read online next page 57 BMA Illustrated Medical Dictionary read online Home Toggle text on/off