ELECTROCARDIOGRAPHY
EMBOLIZATION
E
electrocardiography
See
ECG
.
electrocautery
A technique for destroy-
ing tissue by the application of heat
produced by an electric current. Elec-
trocautery can be used to remove skin
blemishes such as
warts
.
(See also
cau-
terization
;
diathermy
;
electrocoagulation
.)
electrocoagulation
The use of a high-
frequency electric current to seal blood
vessels by heat and thus stop bleeding.
Electrocoagulation is used in surgery;
the current can be delivered through a
surgical knife, enabling the surgeon to
make bloodless incisions. It is also
used to stop nosebleeds and to destroy
abnormal blood vessel formations, such
as
spider naevi
,
in which case the cur-
rent is applied through a fine needle.
electroconvulsive therapy
See
ECT
.
electroencephalography
See
EEG
.
electrolysis
Permanent removal of un-
wanted hair by introducing short-wave
electric current into the hair
follicle
,
which destroys the hair root.
electrolyte
A substance whose mole-
cules dissociate into its constituent
ions
when dissolved or melted.
electromyography
See
EM G
.
electronystagmography
A method of
recording the types of
nystagmus
in
order to investigate their cause. Electri-
cal changes caused by eye movements
are picked up by electrodes placed near
the eyes and are recorded on a graph.
electrophoresis
The
movement
of
electrically charged particles suspended
in a
colloid
solution under the influence
of an electric current. The direction, dis-
tance, and rate of movement of the
particles vary according to their size,
shape, and electrical charge. Electro-
phoresis is used to analyse mixtures (to
identify and quantify the proteins in
blood, for example). It may be used as a
diagnostic test for
multiple myeloma
, a
bone marrow tumour that produces
abnormally high levels of a specific
immunoglobulin
in the blood.
elephantiasis
A disease that occurs in
the tropics, characterized by massive
swelling of the legs, arms, and
scrotum
,
with thickening and darkening of the
skin. Most cases of elephantiasis are
due to chronic lymphatic obstruction
caused by
filariasis
(a worm infestation).
ELISA test
A laboratory blood test
commonly used in the diagnosis of
infectious diseases. ELISA stands for
enzyme-linked immunosorbent assay.
(See also
immunoassay
.)
elixir
A clear, sweetened liquid, often
containing alcohol, that forms the basis
for many liquid medicines, such as
cough remedies
.
embolectomy
Surgical removal of an
embolus
that has blocked an
artery
(see
embolism
).
There are two methods:
either an incision is made in the affect-
ed artery and the embolus is removed
by suction, or it is removed by passing a
balloon catheter
into the affected vessel.
embolism
Blockage of an
artery
by an
embolus
.
Blood clots that have broken
off from a larger clot located elsewhere
in the circulation are the most common
type of embolus.
Pulmonary embolism
is
usually the result of a fragment break-
ing off from a
deep vein thrombosis
and
being carried via the heart to block an
artery supplying the lungs; this is a
common cause of sudden death. Blood
clots may form on the heart lining after
a
myocardial infarction
, or in the atria in
atrial fibrillation
, and then travel to the
brain, resulting in a cerebral embolism,
which is an important cause of
stroke
.
Air embolism
, in which a small artery is
blocked by an air bubble, is rare. Fat
embolism, in which vessels are blocked
by fat globules, is a possible complica-
tion of a major fracture of a limb.
Symptoms of an embolism depend on
the site of the embolus. Pulmonary
embolism can lead to breathlessness
and chest pains. If the embolus lodges
in the brain, a stroke may occur, affect-
ing speech, vision, or movement. If an
embolism blocks an artery to the leg,
the limb will become painful and turn
white or blue. Untreated, gangrene may
develop. In serious cases of fat em-
bolism, heart and breathing rates rise
dramatically, and there is restlessness,
confusion, and drowsiness.
Embolectomy
(surgery to remove the
blockage) may be possible. If surgery is
not possible,
thrombolytic
and
anticoag-
ulant drugs
may be given.
embolization
The deliberate obstruc-
tion of a blood vessel in order to stop
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