An aortic aneurysm is an abnormal bulge in the wall of the aorta.
Enlargement of the aorta may be only mild in degree and termed "ectasia." In general, if the diameter of the aneurysm is
more than 1.5 times the size of the normal aorta, it is called an
Although an aneurysm can develop anywhere along the aorta, abdominal
aneurysms are more common than thoracic ones. An aortic aneurysm is
serious because - depending on its size - it may rupture, causing
life-threatening internal bleeding. The risk of an aneurysm rupturing
increases as the aneurysm gets larger. The risk of rupture also depends
on the location of the aneurysm. When detected in time, an aortic
aneurysm can usually be repaired with surgery.
Aneurysm is 5 times more common in men than in women.
Clinically important aneurysms over 4 cm in diameter are present in
about 1 percent of men between the ages of 55 and 64; the prevalence
increases by 2 to 4 percent per decade thereafter.
The disease is predominant in men of the white race. In black men,
black and white women the incidence of aortic artery aneurysm (AAA) is
38 to 50 percent of the AAA patients suffer from hypertension, 33 to
60% from coronary artery disease, 28% from cerebrovascular diseases and
25% from peripheral occlusive disease.
Causes and risk factors
- Age over 55 years (Risk increases with age)
- A family history of AAA is particularly concerning
- High blood pressure
Most aneurysms are caused by a breakdown in the proteins that provide
the structural strength to the wall of the aorta. These proteins, called
collagen and elastin can gradually deteriorate with age, but
inflammation that is associated with atherosclerosis can accelerate this
process even in younger people. There are also naturally occurring
enzymes that cause the breakdown of collagen and elastin. An excess of
these enzymes or other conditions that activate these enzymes may also
contribute to the formation of an aneurysm, or its sudden growth. In
rare cases an aneurysm may be caused by infection (mycotic aneurysms). There is still much
to be learned about the cause of aneurysms and their growth, but
fortunately we have successful, permanent treatments for AAA when they
occur. Vascular surgeons have performed much of the basic research on
Types of Aortic Aneurysms
Aortic aneurysms are classified by shape, location along the aorta,
and how they are formed.
True aneurysms and pseudoaneurysms
The wall of the aorta is made up of three
layers: a thin inner layer of smooth cells called the endothelium, a
muscular middle layer which has elastic fibers in it called the media,
and a tough outer layer called the adventitia. When the walls of the
aneurysm have all three layers, they are called true aneurysms. If the
wall of the aneurysm has only the outer layer remaining, it is called a pseudoaneurysm. Pseudoaneurysms may occur as a result of trauma when the
inner layers are torn apart.
Most fusiform aneurysms are true aneurysms. The weakness is often
along an extended section of the aorta and involves the entire
circumference of the aorta. The weakened portion appears as a
generally symmetrical bulge.
Occasionally an aneurysm may occur because of a localized
weakness of the artery wall (saccular). Saccular aneurysms appear
like a small blister or bleb on the side of the aorta and are
asymmetrical. Typically they are pseudoaneurysms caused either by
trauma (such as a car accident) or as the result of a penetrating
- Thoracic aortic aneurysm (TAA)
A TAA is a diseased, weakened, and bulging section of the aorta in
the chest. This condition, if not treated, could result in a rupture of
the aorta, leading to life-threatening internal bleeding. The aneurysm
may be caused by vascular disease, injury, or a genetic defect of the
tissue. TAA is sometimes found in people with Marfan?s syndrome, which is characterized by many anomalies
including elongated bones. It is also associated with Turner syndrome,
which results from a missing X chromosome and is associated with
dwarfism and arrested sexual development in addition to aortic aneurysm.
TAA also can run in families independent of those two syndromes.
Because it is difficult to diagnose victims often die young. People with
TAA remain unaware of the risk they face because the slowly enlarging
aorta does not cause any symptoms until it has reached a critical
diameter. At that point, the aorta dissects or ruptures, both of which
are life-threatening. Typically, the patient develops chest pain and usually goes
to an emergency department to seek treatment.
- Abdominal aortic aneurysm (AAA)
More than 90% of abdominal aortic aneurysms originate below the renal
arteries. The diameter is the most important predictor of aneurysm
rupture with up to a 40% risk of rupture over 5 years for aneurysm > 5
cm. When they do rupture they tend to rupture leftward and posteriorly.
Symptoms and signs
Most aortic aneurysms have no symptoms. In fact, most are diagnosed
on a chest X-ray or computerized tomography (CT) scan performed for
evaluation of another condition, such as lung disease, or during routine
exams. Symptoms may occur, however, due to the aneurysm pressing on
nearby organs or tissue, or if the aneurysm leads to dissection.
Symptoms of dissection include severe tearing pain in the chest or back,
stroke, cold or numb extremities, or abdominal pain.
When aortic aneurysms are diagnosed early, treatment is safe and
effective and the aneurysm is cured. AAA can be diagnosed by a simple
ultrasound scan that can be performed in a few minutes without risk or
Men between the ages of 65 and 75 who are or have been smokers should
have a one-time ultrasound to screen for abdominal aortic aneurysm,
according to a new recommendation from the U.S. Preventive Services Task
Force. Nearly 70 percent of men in this age group have smoked and would
benefit from routine screening to check for aneurysms.
Most patients have no symptoms at the time an AAA is discovered.
Aneurysms are often detected on tests that were performed for entirely
different reasons. Abdominal aortic aneurysms may be diagnosed by a
doctor during a physical exam, or sometimes patients notice a pulsating
mass in their abdomen. The first hint of an aortic aneurysm may be an
abnormal chest X-ray. Although AAA can be detected by physical
examination, most are diagnosed today using an ultrasound scan or CAT
scan, simple exams that are non-invasive and can be done as an
outpatient. Magnetic resonance imaging (MRI) can also help. These exams
also tell us about the size of the aneurysms ? the key element to
determine the need for treatment. Since major surgery was required in
the past to repair an aortic aneurysm, that decision depended upon a
comparison of the risk of rupture with risk of the surgery itself. Most
doctors agree that for someone in good health, an AAA larger than 5
centimeters in diameter (about the size of a lemon) needs treatment.
Smaller aneurysms may also need treatment if they cause symptoms (like
back pain or abdominal pain), or tests show that the aneurysm has
rapidly grown larger.
1. Watch and wait
When detected in time, most ruptures can be prevented by repairing the
aneurysms with an operation. Treatment for an aneurysm depends on its
size and location and the general health of the person. If the aneurysm
is small and without symptoms, a "watch-and-wait" approach may be
suggested with regularly scheduled images of the aneurysm to check the
size. However, if the aneurysm is large enough, or if the aneurysm is
growing more than 1 centimeter per year, surgery may be the best option.
Women are more likely than men to die from aortic dissection according
to one of the first studies of its kind reported. Aortic dissections may
involve the ascending aorta alone, the descending thoracic and abdominal
aorta alone, or the entire aorta. The risk of death depends on the
extent of the dissection. It is highest for those aneurysms involving
the ascending aorta. For that reason, most of these aneurysms are
treated surgically as an emergency.
2. Medical treatment
Dissections of the descending
thoracic aorta can often be treated with blood pressure control. The
medical treatment of aortic dissection includes aggressive control of
blood pressure and heart rate while the aorta heals. The risk of death
with medical treatment of descending thoracic aortic dissection is about
10 percent. If surgery is required, however, the risk is higher at about
30 percent. Every effort is therefore made to treat these patients with
3. Endovascular repair of AAA
Recent advances in catheter-based technologies have led to exciting new
treatments for aortic aneurysms. Now, endovascular grafting technology
allows surgeons to repair the AAA by delivering a graft through a small
incision in the groin, rather than the traditional major open surgery.
The endovascular method, approved by the FDA in 1999, allows the graft
to be delivered via a catheter (tube) inserted in a groin artery. In the
operating room, x-ray guidance is used for proper positioning of the
graft. The graft is then expanded inside the aorta and held in place
with metallic hooks rather than sutures. The hospital stay is usually
only one or two days, and most patients can return to work or normal
daily activities in about a week. Even patients with serious medical
problems, once thought to be too sick, or too frail to have surgery for
AAA, may have their aneurysm repaired using an endovascular graft. This
can avoid the need for major open surgery and also eliminate the risk of
fatal rupture if the AAA was not treated at all. It?s very important for
patients to know that endovascular grafting may not be possible in every
case. Endovascular grafts are specially manufactured and don?t ?fit? for
every case. Also, in many cases, standard surgery is still the best
since we don?t have 50 years of experience with these newer procedures
like we do with surgery. There may still be serious problems we haven?t
4. Surgical resection
Surgery is usually required to repair an AAA, but modern, catheter-based
technologies using endovascular grafts have made treatment less invasive
in many cases. The combination of early diagnosis and modern treatment
of aortic aneurysms can save countless lives lost due to aneurysm
rupture each year.
Surgical treatment of AAA has been performed for almost 50 years and is
a successful and durable procedure. In surgery the diseased part of the
aorta is replaced with a Dacron or Teflon graft that is carefully
matched to the normal aorta and is sewn in place by the surgeon. While
ultimately curative, this operation requires a major abdominal incision
and general anaesthesia, and the hospital stay averages 7-10 days for
most patients. Even after uncomplicated surgery, it is often a month or
two before patients can return to a full and normal life. Nevertheless,
more than 90% of patients make a full recovery from surgery. After more
than half a century of experience with these procedures we know that
once patients have recovered, their aneurysms are permanently cured.
Once the acute dissection has healed, adequate control of blood pressure
may eliminate the need for surgery. Lifelong monitoring of diameter of
the aorta is required because a previously dissected descending thoracic
aorta may enlarge and rupture.
Prognosis and survival
Because the abdominal aorta is such a large blood vessel, a ruptured
abdominal aneurysm is a life-threatening event. Fortunately, not all
aneurysms rupture. Many grow very slowly and cause no symptoms or
problems for many years. However, all have the potential to rupture and
thus must be identified and treated or watched very carefully. The
combination of earlier diagnosis with safer, simpler, and ever more
successful treatments can prevent needless deaths due to ruptured
abdominal aortic aneurysms. Timely suspicion and consultation with the
family doctor and a simple ultrasound test can tell whether a person has
The length of the operation and the risks involved depends on the extent
of the repair required, and on the patient's general health. Recovery
time varies. Most people need at least a month or six weeks to recover
from aneurysm surgery. The length of the hospital stay depends on the
patient's condition and the operation performed, but it is typically a
Although endovascular surgery reduces recovery time to a few days, it
still carries risk. And because the procedure is fairly new, long-term
results are unknown. Complications can occur with this procedure, namely
blood leaking from the graft, known as endoleak. For this reason,
patients who have repair of their aortic aneurysms with stent-grafts are
initially required to return for monitoring every six months.
Recent news and research
Cocaine users in their mid-40s are found to have more than four times
the risk of coronary artery aneurysms as non-users as per the Journal of
the American Heart Association. It is believed that cocaine predisposes
to coronary artery aneurysms, and then the aneurysms themselves may
predispose to heart attacks.
The Food and Drug Administration has approved a new device called GORE
TAG Endoprosthesis System that is intended to prevent ruptures of
descending thoracic aneurysms by making a new path for blood flow. It is
the first endovascular grafting system approved to treat aneurysms of
the thoracic aorta.