Abdominal
Aortic Aneurysm Screening & Treatment Options
Common Questions & Answers
What is an aneurysm?
What is an aortic aneurysm?
What are the thoracic and abdominal aorta?
Where do aortic aneurysms tend to develop?
What shape are most aortic aneurysms?
What's inside an aortic aneurysm?
Who is most likely to have an abdominal aortic aneurysm?
What is the most common cause of aortic aneurysms?
What are other causes of aortic aneurysms?
What are the symptoms of an abdominal aortic aneurysm?
How is an abdominal aortic aneurysm diagnosed clinically?
What tests help in the diagnosis of an abdominal aortic
aneurysm?
What is the natural history of abdominal aortic aneurysms?
What are the complications with an abdominal aortic
aneurysm?
How are abdominal aortic aneurysms repaired?
What is done if an abdominal aortic aneurysm threatens
to rupture?
What happens if an abdominal aortic aneurysm ruptures?
Abdominal Aortic Aneurysm At A Glance
What is an aneurysm?
An aneurysm is an area of a localized widening (dilation)
of a blood vessel. (The word "aneurysm" is borrowed
from the Greek "aneurysma" meaning "a widening").
What is an aortic aneurysm?
An aortic aneurysm involves the aorta, one of the large arteries
that carries blood from the heart to the rest of the body.
The aorta bulges at the site of the aneurysm like a weak spot
on an old worn tire.
What are the thoracic and abdominal aorta?
The aorta is first called the thoracic aorta as it leaves
the heart, ascends, arches, and descends through the chest
until it reaches the diaphragm (the partition between the thorax
and abdomen). The aorta is then called the abdominal aorta
after it has passed the diaphragm and continues down the abdomen.
The abdominal aorta ends where it splits to form the two iliac
arteries that go to the legs.
Where do aortic aneurysms tend to develop?
Aortic aneurysms can develop anywhere along the length of
the aorta. The majority, however, are located along the abdominal
aorta. Most (about 90%) of abdominal aneurysms are located
below the level of the renal arteries, the vessels that leave
the aorta to go to the kidneys. About two-thirds of abdominal
aneurysms are not limited to just the aorta but extend from
the aorta into one or both of the iliac arteries.
What shape are most aortic aneurysms?
Most aortic aneurysms are fusiform. They are shaped like a
spindle ("fusus" means spindle in Latin) with widening
all around the circumference of the aorta. (Saccular aneurysms
just involve a portion of the aortic wall with a localized
out pocketing).
What's inside an aortic aneurysm?
The inside walls of aneurysms are often lined with a laminated
blood clot that is layered like a piece of plywood.
Who is most likely to have an abdominal aortic aneurysm?
Abdominal aortic aneurysms are most common after age 60. Males
are 5 times more likely than females to be affected. This means
men over 60 are at highest risk to develop an abdominal aortic
aneurysm. Approximately 5% of men over age 60 develop an abdominal
aortic aneurysm.
What is the most common cause of aortic aneurysms?
The most common cause of aortic aneurysms is "hardening
of the arteries" called arteriosclerosis. At least 80%
of aortic aneurysms are from arteriosclerosis. The arteriosclerosis
can weaken the aortic wall and the pressure of the blood being
pumped through the aorta causes expansion at the site of weakness.
What are other causes of aortic aneurysms?
Other causes of aortic aneurysms include:
- Genetic: There is a familial tendency to aortic aneurysms.
This tendency is at least in part genetic. Among the inheritable
causes of aortic aneurysms are connective tissue disorders
such as Ehlers-Danlos syndrome and Marfan's syndrome.
- Post-traumatic: After physical trauma to the aorta.
- Arteritis (inflammation of blood vessels) as occurs in
Takayasu disease, giant cell arteritis, and relapsing polychondritis.
- Congenital malformation of the aorta (aneurysms tend to
develop just beyond the narrowing of a coarctation of the
aorta; also with what is called a ductus diverticulum).
- End-stage (tertiary) syphilis, which tends to affect the
ascending aorta and arch of the aorta.
- Mycotic (fungal) infection which may be associated with
immunodeficiency, IV drug abuse, heart valve surgery.
What are the symptoms of an abdominal aortic aneurysm?
Abdominal aortic aneurysms may cause pain. The pain typically
has a deep quality as if it is boring into the person. It is
felt most prominently in the lower back region. The pain is
usually steady but may be relieved by changing position. The
person may also become aware of an abnormally prominent abdominal
pulsation. However, many aneurysms are without symptoms. They
may become large and even rupture without warning.
How is an abdominal aortic aneurysm diagnosed clinically?
Careful feeling of the abdomen by the doctor may reveal the
abnormally wide pulsation of the abdominal aorta. This is characteristically
felt on both sides of the aorta which is in the midline. Note
that even large aneurysms can be very difficult to detect on
physical examination in overweight people. Aneurysms that are
rapidly enlarging and on the verge of rupture are often tender.
What tests help in the diagnosis of an abdominal
aortic aneurysm?
X-rays of the abdomen show calcium deposits in the aneurysm
wall in about 90% of cases. Ultrasonography usually gives a
clear picture of the extent and size of an aneurysm. Ultrasound
has about 98% accuracy in measuring the size of the aneurysm.
CT scanning of the abdomen, particularly with contrast medium,
can be highly accurate in determining the size and shape of
the aneurysm. MRI scanning is similarly accurate but is rarely
necessary. Abdominal aortography shows the origin of the major
blood vessels arising from the aorta and reveals the size and
extent of any aneurysm. Contrast aortography is especially
useful if there is extension of the aneurysm above the renal
arteries and in delineating a mural thrombus (a clot clinging
to the wall of the aneurysm).
What is the natural history of abdominal aortic aneurysms?
The natural history of abdominal aortic aneurysms depends
on their size. Rupture of aneurysms is uncommon when they are
less than 5 cm wide. Rupture is far more common in aneurysms
that are over 6 cm wide. Surgical repair is therefore usually
recommended for all aneurysms over 6 cm wide. Elective repair
is also generally recommended for aneurysms between 4 and 6
cm in patients who are good surgical risks.
What are the complications with an abdominal aortic
aneurysm?
Rupture is a feared problem. Half of all persons with untreated
abdominal aortic aneurysms die of rupture within 5 years. Abdominal
aortic aneurysms are the 13th leading cause of death in the
U.S. Peripheral embolization of clot within the aneurysm can
occur when a piece of clot comes loose and travels further
out in the arterial system. This clot fragment can lodge in
a smaller artery and block the flow of blood. Infection of
aneurysms can occur from turbulent blood flow from the rough
inner surface. Spontaneous blockage of the aorta can also occur.
How are abdominal aortic aneurysms repaired?
Traditionally, repair of an aortic aneurysms has been surgical.
The surgery has usually consisted of opening the abdomen, removing
(excising) the aneurysm, and sewing a synthetic (Dacron) tube
in its place.
More recently, "minimally invasive" procedures
have been devised using stent grafts that can be guided to
the site of the aneurysm without the need to cut open the abdomen.
The first stent graft was installed in 1991 by Dr. Juan Parodi
in Argentina.
A stent graft developed by Dr. Thomas Fogarty at Stanford
is a Dacron tube inside a collapsed metal-mesh cylinder. To
install the stent, a small incision is made in the thigh to
gain access to the femoral artery. The stent, about 6 inches
(15 cm) long, is guided inside a long plastic capsule through
the arteries to the lower aorta. Once the stent is in place,
the holding capsule is removed. Activated by heat, the stent
expands like a spring and becomes anchored to the artery wall.
The by-passed aneurysm then is shielded from the blood flow
and typically shrinks over time.
According to a U.S. national multi-center study reported
by Dr. Christopher Zari from Stanford in 1998, the "minimally
invasive" installation of the stent graft carries a lower
rate of complications and permits people to get back on their
feet faster than traditional open surgery.
What is done if an abdominal aortic aneurysm threatens
to rupture?
Threatened rupture of abdominal aneurysms is a surgical emergency.
The operative risk for a ruptured aneurysm is about 50%. If
kidney failure occurs after surgery, the prognosis (outlook)
is particularly poor.
What happens if an abdominal aortic aneurysm ruptures?
Rupture of an abdominal aneurysm is a catastrophe. It is
highly lethal and is usually preceded by excruciating pain
in the lower abdomen and back, with tenderness of the aneurysm.
Rupture of an abdominal aneurysm causes profuse bleeding and
leads to shock. Death may rapidly follow.
Abdominal Aortic Aneurysm At A Glance
- An aneurysm is an abnormal area of localized widening
of a blood vessel.
- The aorta bulges at the site of an aneurysm like a weak
spot on a worn tire.
- Aortic aneurysms are typically spindle-shaped and involve
the aorta below the arteries to the kidneys.
- Five percent of men over 60 develop an abdominal aortic
aneurysms.
- The most common cause of an aneurysm is arteriosclerosis.
- Abdominal aortic aneurysms often do not cause symptoms.
If they do, they may cause deep boring pain in the lower
back or abnormally prominent abdominal pulsation.
- X-rays of the abdomen and other radiologic tests can be
used in diagnosing an aneurysm.
- Rupture of an aortic aneurysm is a catastrophe.
- Repair of the aneurysm can be done by surgery or by installation
of a stent graft.
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