Bma Illustrated Medical Dictionary

such as the fear of open spaces or spi-
ders, that lead to avoidance of certain
situations or objects.
Counselling, psychotherapy, and group
or individual cognitive–behaviour ther-
apy are used to treat anxiety disorders.
Antianxiety drugs(especially benzodi-
azepine drugs) may be used for short-
term treatment but are addictive.
anxiolyticsSee antianxiety drugs.
aortaThe body’s main artery, which
supplies oxygenated blood to all other
parts. The aorta arises from the left ven-
tricle (the main pumping chamber of
the heart) and arches up over the heart

before descending, behind it, through
the chest cavity. It terminates in the
abdomen by dividing into the 2 com-
mon iliac arteries of the legs.
The aorta is thick-walled and has a
large diameter in order to cope with the
high pressure and large volume of blood
passing through it. (See also arteries,
disorders of; circulatory system.)
aortic incompetenceLeakage of blood
through the aortic valve (one of the
heart valves), resulting in a backflow of
blood from the aorta into the left ventri-
cle (the heart’s main pumping chamber).
Failure of the aortic valve to close
properly may be due to a congenital
abnormality in which the valve has 2
flaps rather than 3. The valve leaflets

can be destroyed by infective endocardi-

tis. Aortic incompetence is associated

with ankylosing spondylitis, and Marfan’s

syndrome. Atherosclerosismay damage

the valve, causing a combination of aor-

tic stenosisand incompetence. Aortic

incompetence is also found in untreat-

ed syphilis, which is now rare.

Aortic incompetence may not cause

symptoms and is sometimes found dur-

ing a routine medical examination. The

heart compensates for the backflow of

blood into the left ventricle by working

harder, which may eventually lead to

heart failure; this causes breathing diffi-

culty and oedema(fluid accumulation).

Chest X-ray, ECG, and echocardiogra-

phymay be carried out to diagnose

aortic incompetence. A cardiac catheter

is sometimes used to demonstrate the

degree of incompetence (see catheter-

ization,cardiac). Heart failure resulting

from aortic incompetence can be treated

with diuretic drugs. Heart-valve surgery

to replace the damaged valve may

eventually be necessary.

aortic stenosisNarrowing of the open-

ing of the aortic valve (one of the heart

valves), causing obstruction of blood flow

into the circulation. This makes the heart

work harder and causes the muscle in

the wall of the left ventricle (the main

pumping chamber) to thicken. Narrowing

of the valve also reduces the amount of

blood flowing into the coronary arteries.

The most common cause of aortic

stenosis is deposition of calcium on the

aortic valve, usually associated with

atherosclerosis. Aortic stenosis may also

be caused by a congenitalabnormality.

Aortic stenosis may not cause symp-

toms. When symptoms do occur, they

ANXIOLYTICS AORTIC STENOSIS

A

Vena cava

AORTA

Heart

Aorta

Descending
aorta

Descending
vena cava

NORMAL AORTA STENOSED AORTA

Cusp

Normal

blood

flow

Abnormal

cusp

Restricted

blood

flow

AORTIC STENOSIS