Bma Illustrated Medical Dictionary

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-
rosiscan lead to myocardial infarction.
(See also coronary artery disease.)
coronary artery bypassA major heart
operation to bypass narrowed or blocked
coronary arteriesusing additionalblood
vessels (such as a mammary artery) to
improve blood flow to the heart muscle.
This operation is usedwhen 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
machineduring the operation. The long
term outlook after a bypass is good, but
the grafted vessels may also eventually
become blocked by atherosclerosis.
coronary artery diseaseNarrowing
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 angioplastyor coronary artery

bypass surgery.

coronary care unitA 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 diseaseAn alterna-

tive name for coronary artery disease.

coronary thrombosisNarrowing 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).

coronerA 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 pulmonaleEnlargement 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 failurewith oedema.

corpuscleAny minute body or cell, par-

ticularly red and white blood cells or

certain types of nerveendings.

corpus luteumA small tissue mass in

the ovarythat develops from a ruptured

egg follicleafter ovulation. The corpus

CORONARY ARTERY BYPASS CORPUS LUTEUM

C

CORPUS LUTEUM

Immature

egg follicle

Empty follicle

(corpus luteum)

LOCATION

Mature egg

follicle

Egg

STRUCTURE OF AN OVARY

Blood

vessel