CORONARY ARTERY BYPASS
CORPUS LUTEUM
known as the left and right main coro-
nary arteries and arise directly from the
aorta.
The term coronary artery is also ap-
plied to any of the arteries that branch
off from the main coronary arteries, such
as the left circumflex artery and the left
anterior descending artery. Blockage of a
coronary artery as a result of
atheroscle-
rosis
can lead to
myocardial infarction
.
(See also
coronary artery disease.
)
coronary artery bypass
A major heart
operation to bypass narrowed or blocked
coronary arteries
using additional blood
vessels (such as a mammary artery) to
improve blood flow to the heart muscle.
This operation is used when symptoms
of coronary artery disease have not been
relieved by drugs or balloon
angioplasty
.
Before surgery, sites of blockage in the
arteries are identified using angiogra-
phy. In some cases,
minimally invasive
surgery
can be used, avoiding the need
to stop the heart and use a
heart-lung
machine
during the operation. The long
term outlook after a bypass is good, but
the grafted vessels may also eventually
become blocked by
atherosclerosis
.
coronary artery disease
Narrowing
of the coronary arteries, which supply
blood to the heart, leading to damage
or malfunction of the heart. The most
common heart disorders due to coro-
nary artery disease are
angina pectoris
and
myocardial infarction
(heart attack).
The usual cause of narrowing of the
arteries is
atherosclerosis
, in which fatty
plaques develop on the artery linings.
The vessel can become totally blocked if
a blood clot forms or lodges in the nar-
rowed area. Atherosclerosis has many
interrelated causes including smoking,
a high-fat diet, lack of exercise, being
overweight, and raised blood cholesterol
levels. Other factors include a genetic
predisposition and diseases such as
diabetes mellitus
and
hypertension
.
The first symptom of coronary artery
disease is frequently the chest pain of
angina. Treatment is with drugs such as
glyceryl
trinitrate
and
other
nitrate
drugs
,
beta-blockers
,
calcium channel
blockers
,
potassium channel activators,
and
vasodilator drugs
.
If drug treatment
fails to relieve the symptoms, or there is
extensive narrowing of the coronary
arteries, blood flow may be improved by
balloon
angioplasty
or
coronary artery
bypass
surgery.
coronary care unit
A specialist ward
for the care of acutely ill patients who
may be suffering, or who have suffered,
a
myocardial infarction
(heart attack) or
another serious cardiovascular disorder.
coronary heart disease
An alterna-
tive name for
coronary artery disease
.
coronary
thrombosis
Narrowing or
blockage of one of the
coronary arteries
by a
thrombus
(blood clot), depriving a
section of the heart muscle of vital oxy-
gen. In most cases, the thrombus forms
in a blood vessel already narrowed by
atherosclerosis
. Sudden blockage of a
coronary artery causes an acute
myo-
cardial infarction
(heart attack).
coroner
A public officer appointed to
inquire into the cause of death when it
is unknown, or when it is suspected or
known to result from unnatural causes.
The coroner holds an inquest, some-
times before a jury.
cor pulmonale
Enlargement and strain
of the right side of the
heart
caused by
one of a number of chronic lung diseases.
Lung damage results in
pulmonary hy-
pertension;
the resultant “back pressure”
strain on the heart may eventually cause
right-sided
heart failure
with
oedema
.
corpuscle
Any minute body or cell, par-
ticularly red and white blood cells or
certain types of
nerve
endings.
corpus luteum
A small tissue mass in
the ovary that develops from a ruptured
egg
follicle
after
ovulation.
The corpus
STRUCTURE OF AN OVARY
147
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