Definition
Aneurysm
Circumscribed dilation of an artery due to weakening of the wall.
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Radiographic Appearance
In plain radiography aneurysms are detected when the wall of
the artrey contains calcifications making it visible, demonstrating
a widening..
In angiography the contrast media visualises the bore of the artery
demonstrating the aneurysm.
The gold standard for evaluation of aneurysms is angiography. By
using a helical technique to obtain a volumetric data set, one adds
a useful minimally-invasive method of evaluating vessel wall and
branch vessels to the traditional angiography evaluation. With a
volumetric data set, one can provide additional information such as
the location of the neck of the aneurysm, its size, its orientation
in relation to the parent vessel, its location in reference to
branch vessels and surrounding vessels, calcification, and stenoses
or dilitation in branch vessels. Tools used to generate this
information include several basic volumetric tools: oblique
sectioning, region of interest analysis, geometric analysis of outer
aortic boundaries and vessel tortuosity, and volume rendering, and
surface rendering.
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Pathology
An aneurysm is a localized, abnormal dilatation of a vessel, in this
case the aorta. Atherosclerosis and cystic medial necrosis are the
two most common causes, but syphilis, trauma, infection, and
vasculitis can also cause aneurysms. The shape of the aneurysm can
be fusiform, saccular (spherical), or berry (small spherical).
Types:
true: all layers of wall intact
false: all layers of wall disrupted
fusiform: circumferential involvement
saccular: involvement of portion of wall
Etiology:
atherosclerosis (80%): descending aorta
post-traumatic (15%)
congenital (2%): post coarctation, ductus diverticulum
syphilis: ascending aorta and arch
Typical size is 4 -5 cm and rupture accurs at around 10cm
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Treatment:
Surgery is almost always needed when the diameter of an
aneurysm enlarges to at least 2 inches. The operation involves an
incision into your abdomen to open the aorta and remove cholesterol
and fatty buildup. The surgeon implants a flexible tube (graft) to
replace the enlarged artery. Recovery from elective surgery takes
about six weeks, including a one-week hospital stay.
Emergency repair of a ruptured aortic aneurysm is less
successful--62 percent of people die before they reach the hospital.
Of those who have surgery, 50 percent live.
As an alternative to abdominal surgery, the American Heart and
Lung Institute located in San Jose California is one of several
medical centers investigating a new procedure called endovascular
surgery. It involves passing a collapsed graft up the femoral artery
in your leg into the weakened aorta, then securing the graft with
metallic stents. Similar to balloon angioplasty, the graft is then
inflated to restore normal blood flow.
Endovascular surgery may become a safer and easier alternative to
traditional surgery, especially for people at high surgical risk.
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Image 1
Lateral chest demonstraing an aortic aneurysm
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