VAPORIZER
VASECTOMY
V
be performed as
open heart surgery.
However,
the
technique of balloon
valvuloplasty makes it possible to treat
a narrowed valve without opening the
chest. A
balloon catheter
is passed
through the skin into a blood vessel
and from there to the heart. Inflation of
the balloon via the catheter then sepa-
rates the flaps of a narrowed valve.
vaporizer A device for converting a
drug or water into a fine spray so that
medication can be taken by inhalation
or so that inhaled air can be moistened.
variant angina A form of
angina
that
causes chest pain at rest, often during
sleep. The pain may occur with breath-
lessness and
palpitations.
The cause is
thought to be narrowing of the
coronary
arteries
by muscular spasm in their
walls. Treatment with
calcium channel
blockers
or
nitrates
is usually effective.
varicella Another name for
chickenpox.
varicella-zoster The virus that causes
chickenpox
and
shingles
.
varices Enlarged, tortuous, or twisted
sections of vessels, usually veins. Varices
is the plural of varix. A vein affected by
varices is called a
varicose vein.
varicocele
Varicose veins
surrounding a
testis
. Varicocele is a common condi-
tion. It almost exclusively affects the left
testis and is usually harmless, although
there may be aching in the
scrotum
or
an abnormally low sperm count (see
infertility).
Aching may be relieved by
supportive underwear. Surgery to divide
and tie off the swollen veins may be
performed if the sperm count is low.
varicose veins Enlarged, tortuous
veins
just beneath the skin. Varicose veins
most often occur in the legs but can
also occur in the anus (see
haemor-
rhoids),
oesophagus (see
oesophageal
varices
), and scrotum (see
varicocele
).
A defect of the
valves
in the leg veins
causes blood to pool in the veins near
the surface of the skin, causing them to
become varicose. Contributing factors
include
obesity
, hormonal changes and
pressure on the pelvic veins during
pregnancy
, hormonal changes occurring
at the
menopause
, and standing for long
periods of time. Varicose veins are com-
mon, tend to run in families, and affect
more women than men.
Varicose veins may not cause any prob-
lems but may ache severely; swollen
feet and ankles and persistent itching
may occur. These symptoms may wors-
en during the day and can be relieved
only by sitting with the legs raised. In
women, symptoms are often worse just
before menstruation. In severe cases,
leg ulcers
may occur.
Thrombophlebitis
may be associated with varicose veins.
Usually, support stockings, regular walk-
ing, and sitting with the feet up as
much as possible are the only measures
required. In more severe cases,
scle-
rotherapy
may be carried out. Varicose
veins may require surgical removal if
they become painful or ulcerated, but
they may later develop elsewhere.
variola Another name for
smallpox
.
varus The medical term for an inward
displacement of part of the body.
vascular Relating to the blood vessels
(see
circulatory system
).
vasculitis Inflammation of blood ves-
sels. Vasculitis usually leads to damage
to the lining of vessels, with narrowing
or blockage, that restricts or stops
blood flow. As a result, the body tissues
supplied by the affected vessels are
damaged or destroyed by
ischaemia
.
Vasculitis is thought to be caused in
most cases by the presence of minute
bodies, called immune complexes, in the
circulating blood. Immune complexes
(consisting of
antigens
bound to
anti-
bodies
) are normally destroyed by white
blood cells, but sometimes adhere to
the walls of blood vessels, where they
cause inflammation. In some cases, the
antigens are
viruses
. Vasculitis is the
basic disease process in a number of
disorders, including
polyarteritis nodosa
,
erythema nodosum, Henoch-Schonlein
purpura
,
serum sickness
,
temporal arter-
itis,
and
Buerger's disease.
vas deferens Either of a pair of tubes
that convey
sperm
from each
testis
and
epididymis
to the
urethra
. The plural
form is vasa deferentia.
vasectomy The operation of male ster-
ilization. Vasectomy is a minor surgical
procedure,
performed
under
local
anaesthetic (see
anaesthesia, local),
that
consists of cutting out a short length of
each
vas deferens
. After vasectomy, the
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