What is an Aneurysm?
Simply stated, an aneurysm is a widening of an artery. That is, the width the artery increases to more
than 50% of its “original” size. Arteries,
in some respects, behave much like water balloons; that is, as the artery widens, the
walls become thinner and as the walls become thinner, the artery is more likely to
“pop” or rupture. Rupture of an
aneurysm—anywhere in the body—carries with it significant clinical problems.
The most common location—but by no means the only
location—for aneurysms to occur is in the large artery in the abdomen, the aorta. This is the artery that begins at the heart and
supplies bloods to all of the organ systems of the body as it travels downward towards the
legs. Branches are given off to the arms, the
brain, the lung, the liver, the intestines, and the kidneys (to name only a few of the
organs) before the aorta “splits” into two arteries at the level of the
umbilicus (“belly button”) providing one artery to each leg. The aneurysms most commonly occur in the portion
of the aorta that is in the abdomen—below the level where the aorta gives off its
branches to the kidneys.
How Can I Tell if I Have an Aneurysm?
Most aneurysms are detected incidentally at the time of an
examination for an unrelated problem! Most
often a person will be undergoing a type of imaging study (x-ray test) of the abdomen when
an aneurysm is discovered. It is most often
an unexpected finding—both to the patient and the physician!
There are times when a careful
examination of the patient’s abdomen may reveal an aneurysm that is then confirmed by
an ultrasound or a CT Scan. This is more
common in thinner patients whose aorta may be more readily palpable.
When an aneurysm produces symptoms (something that makes the person recognize that they
have this condition) it is often at the time that the aneurysm has ruptured or
“leaked.” It is unusual for a
person to notice a pulsating mass in their abdomen and bring it to the attention of their
physician. It is also unusual for a person to
experience symptoms in the absence of a rupture of the aneurysm—such as abdominal,
back or groin pain.
Radiographic
procedures will confirm the presence of an abdominal aortic aneurysm. An ultrasound is a simple, noninvasive test that
will give rapid and accurate results. If an
aneurysm is detected, most physicians would rely on a CT Scan to better define the anatomy
of the aneurysm which would allow one to make treatment recommendations with more
accuracy. Angiograms are not generally
obtained except in the planning stages for endovascular stent grafting procedures.
Must My Aneurysm Be Repaired?
The
question as to when to repair an aneurysm is based on many factors and constitutes,
in part, the art of medicine. Opinions differ
among experts as to when an aneurysm should be repaired and what criteria are most
important in making that decision. There are
generally accepted criteria but none are “hard and true” and each patient must
be considered individually.
Historically, many vascular surgeons have relied on a diameter of 5 cm (approximately 2
inches) to be the point at which repair should be considered. However, this is based on the fact that most
“normal” (nonaneurysmal) aorta are approximately 2-2.5 cm in diameter—thus,
making the cutoff at 2-2.5 times the normal diameter!
There are, however, very important additional factors to consider when
making recommendations for intervention; these
include the age of the patient, comorbid medical illnesses, life expectancy, rate of
growth of the aneurysm (if available), size of the adjacent “normal”
aorta—to name only a few! The decision
to intervene requires consideration of all of these factors in addition to consultation
with the primary care physician caring for the patient!
What are the Treatment Options
Available?
The standard treatment for
abdominal aortic aneurysms (AAA) has been open surgical repair. This operation entails replacement of the
aneurysmal aorta with a synthetic fabric tube (Dacron or other substance) that extends
from the normal aorta above the aneurysm to a point on the arterial tree below
the aneurysm (that is, from “normal artery” to “normal artery”.) This has involved a rather extensive operative
procedure that is performed wither through an incision in the middle of the abdomen or one
along the left flank. The hospital stay is
typically 4-10 days and the recuperation varies from 3-4 weeks to 6-12 months! The operation was first performed in the 1950s and
has changed very little since that time. The
durability is outstanding with very few recurrences at the same site!
Recently
(early 1990s) the development of Endovascular Stent Grafting has gained attention. This procedure involves repair of the AAA using a
less invasive technique. There have been
several devices available for insertion—only two of which currently have full
FDA approval (Medtronics AVE AneuRx and Guidant
Ancure.) The procedure allows for repair of
the abdominal aortic aneurysm through two small incisions on the lower abdomen or groin
and a hospital stay of 24-48 hours! The
recuperation time is markedly improved—1-6 weeks—as the post-operative course is
much smoother. Patients undergoing this
procedure are usually eating dinner on the evening of the surgery and able to ambulate
that same day—a vast improvement over the standard open repair!
Why Not Perform an Endovascular Repair Always?
This question is actively debated in many centers in the United
States and throughout the world! There exists
a subset of patients for whom endovascular repair is not an option. When considering the currently approved devices,
these include patients whose aneurysm begins too close to the level of the kidney
arteries, those whose vessels may be severely calcified (hardened) or those whose vessels
between the groin and the aneurysm (iliac arteries) are too small to accept passage of the
device.
Most importantly, in our opinion, is the fact that the longer-term
data is not yet available on endovascular stent grafting.
Thus, when considering a patient for repair of their AAA, the patient’s
longevity must be a factor entered into consideration!
Once long-term data is available, the utility of endovascular grafting on a
wider scale may become more prevalent.