Aneurysm
I. Abdominal Aortic Aneurysm
II. Thoracic Aortic Aneurysm
III. Aortic Dissection
IV. Berry Aneurysm
GLOSSARY
aneurysm a ballooning of the wall of an artery or the heart
caused by severe weakening of the walls of the artery or the
heart muscle. atheroma same as atherosclerosis, raised plaques filled with
cholesterol, calcium, and other substances on the inner wall of
arteries that obstruct the lumen and the flow of blood; the
plaque of atheroma hardens the artery, hence the term
atherosclerosis (sclerosis ¼ hardening). heart failure failure of the heart to pump sufficient blood from
the chambers into the aorta; inadequate supply of blood
reaches organs and tissues. hypotension marked decrease in systolic blood pressure, usually
less than 95 mmHg. intima the innermost lining of the vessel wall that is in contact
with flowing blood. media the middle wall of arteries. syncope temporary loss of consciousness caused by lack of
blood supply to the brain; fainting describes a simple syncopal
attack. wall tension force exerted on the vessel or chamber wall acting
to pull it apart in a circumferential direction; it is a function of
the radius and the pressure within the lumen or chamber.
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- I. ABDOMINAL AORTIC ANEURYSM
A. Pathogenesis - II. THORACIC AORTIC ANEURYSM
Aneurysms of the aorta in the chest are much less com¬mon than abdominal aneurysms. They are classified as the ascending, arch, or descending aortic aneurysms. Because of the etiology and natural history, treatment differs for each of these aortic segments. Aneurysms of the descend¬ing thoracic aorta are the most common and have similar causes as those of abdominal aneurysms. Aneurysms of the descending aorta usually result from a cystic medial necrosis; the etiology of which remains unknown. Also, cystic medial necrosis is observed in nearly all cases of Marfan syndrome. Another rare connective tissue disorder, Ehlers-Danlos syndrome, may involve the aorta. Syphilis was a common cause of ascending thoracic aneurysms, but is now rare because aggressive antibiotic therapy cures the disease in its early stages. In these cases chest x-ray showed typical linear calcification of the dilated ascending thoracic aorta. - III. AORTIC DISSECTION
Ascending aortic aneurysms may undergo internal tearing or dissection resulting in an extremely high mortality of up to 1% per minute and 60% in 60 minutes. Thus, time-consuming investigations that are not sufficiently sensitive or specific, such as CTscans, are usually not recom¬mended. Emergency surgery carries the only hope of sur¬vival for patients with dissecting aneurysms, and immediate accurate diagnosis is mandatory to guide therapy. - IV. BERRY ANEURYSM
A different type of aneurysm can occur at the base of the brain. The arteries at this site may have a develop¬mental defect and form small berry-like aneurysms that may remain asymptomatic until a rupture occurs when the individual is between 20 and 50 years old. A subarach-noid hemorrhage at the base of the brain may damage the brain substance and cause coma, death, or severe disability.