electrocardiographySee ECG.
electrocauteryA 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.)
electrocoagulationThe 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 therapySee ECT.
electroencephalographySee EEG.
electrolysisPermanent removal of un-
wanted hair by introducing short-wave
electric current into the hair follicle,
which destroys the hair root.
electrolyteA substance whose mole-
cules dissociate into its constituent
ionswhen dissolved or melted.
electromyographySee EMG.
electronystagmographyA method of
recording the types of nystagmusin
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.
electrophoresisThe movement of
electrically charged particles suspended
in a colloidsolution 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
immunoglobulinin the blood.
elephantiasisA 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 testA laboratory blood test
commonly used in the diagnosis of
infectious diseases. ELISA stands for
enzyme-linked immunosorbent assay.
(See also immunoassay.)
elixirA clear, sweetened liquid, often
containing alcohol, that forms the basis
for many liquid medicines, such as
cough remedies.
embolectomySurgical removal of an
embolusthat 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 catheterinto the affected vessel.
embolismBlockage of an arteryby 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 thrombosisand
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 drugsmay be given.
embolizationThe deliberate obstruc-
tion of a blood vessel in order to stopELECTROCARDIOGRAPHY EMBOLIZATIONE