I
ANGINA PECTORIS
TYPES OF ANEURYSM
An aneurysm forms when pressure from the blood flow causes a weakened artery
wall to distend or forces blood through a fissure. Aneurysms can form anywhere in
the body, although the most common sites are the aorta and the arteries
supplying the brain.
Outer coat
Common aneurysm
This type forms when the tunica media, the
artery’s middle wall, isweakened; the strong force
of the blood flow distends the wall of the artery.
Dissecting aneurysm
In this type, blood is forced through a fissure in
the internal wall ofthe artery. The internal lining
is stripped away, forming a false channel.
Cerebral (or berry)
aneurysm
A swelling where
arteries branch, often
atthe base ofthe
brain, usually caused
by congenital
weakness.
Saccular aneurysm
A balloon-shaped
distension of part of
the wall of an artery,
often seen in aortic
aneurysms just above
the heart.
Fusiform aneurysm
A spindle-shaped
distension around
the circumference
of an artery, often
seen in lower aortic
aneurysms.
by
ultrasound scanning,
by
amniocentesis,
or by
fetoscopy;
if anencephaly is detect-
ed, termination of the pregnancy may
be considered (see
abortion, induced).
Anencephaly is caused by a failure in
the development of the neural tube,
which is the nerve tissue in the embryo
that normally develops into the spinal
cord and brain (see
neural tube defects).
aneurysm
Abnormal dilation (ballooning) of an
artery
caused by the pressure of blood
flowing through a weakened area. The
weakening
may
be
due
to
disease,
injury, or a congenital (present from
birth)
defect
of
the
arterial
wall.
Aneurysms most commonly affect the
aorta
and arteries supplying the brain.
TYPES AND CAUSES
The most common cause of an aneu-
rysm is
atherosclerosis,
a condition in
which fatty deposits weaken the artery
wall. The aorta is the usual site of
atherosclerotic aneurysms.
Less commonly, aneurysms may be
due to a congenital (present from birth)
weakness of the artery walls. Most cere-
bral aneurysms, known as
berry aneurysms
because of their appearance, are con-
genital.
Marfan syndrome,
an inherited
disorder in which the wall of the aorta
is defective, is often associated with
aneurysms just above the heart. The
arterial wall can also be weakened by
inflammation, as occurs in
polyarteritis
nodosa.
A dissecting aneurysm is one in
which the inner layer of the artery wall
ruptures, allowing blood to track along
the length of the artery and block any
branching
arteries. Ventricular
aneu-
rysms are aneurysms that sometimes
develop in the heart wall due to weaken-
ing of an area of heart muscle as a result
of a heart attack (see
myocardial infarction).
Some of the common types, sites, and
shapes of aneurysm are shown in the
illustrated box.
SYMPTOMS AND SIGNS
Most aneurysms are symptomless and
remain
undetected.
However,
if the
aneurysm expands rapidly and causes
pain, or is very large, the symptoms are
due to pressure on nearby structures.
Aneurysms
may
eventually
rupture,
cause fatal blood loss, or, in the case of a
cerebral aneurysm, loss of conscious-
ness (see
subarachnoid haemorrhage).
A
d
issecting aneurysm
usually causes severe
pain, and there is a high risk of the ves-
sel
rupturing. Ventricular
aneurysms
seldom rupture, but they interfere with
the pumping action of the heart.
DIAGNOSIS AND TREATMENT
Aneurysms of the aorta may be detected
by
ultrasound scanning,
and
cerebral
aneurysms by
CT scanning
or
MRI. Angi-
ography
can
provide
more
detailed
information on all types of aneurysm. A
ruptured or enlarged aneurysm requires
immediate
arterial reconstructive surgery.
(See also
microaneurysm.)
angina
A strangling or constrictive pain. The
term angina has become synonymous
with the heart disorder
angina pectoris
.
Other types of angina include abdo-
minal
angina
(abdominal pain after
eating caused by poor blood supply to
the intestines)
and Vincent’s angina,
which is pain caused by inflammation
of the mouth (see
Vincent’s disease).
angina pectoris
Pain in the chest that is the result of
insufficient oxygen being carried to
the heart muscle in the blood. The pain
of angina pectoris usually occurs when
the
heart
is
working
harder
and
requires more oxygen, such as during
exercise or at times of stress.
CAUSES
Inadequate blood supply to the heart
is usually due to
coronary artery disease
,
in which the
coronary arteries
are
A
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