Aortic Aneurysm

Abdominal aortic aneurysm is the thirteenth leading cause of death in the United States and is responsible for 0.8% of all deaths — AAA is the tenth leading cause of death in older men.

Abdominal Aortic Aneurysm

An abdominal aortic aneurysm is a focal dilatation of the 3 layers of the abdominal aorta vessel wall of at least 50% more than the expected normal diameter (or proximal segment) of the aorta.7 Aortic diameter may vary accord­ing to age, sex, race, height, weight, body surface area, and baseline blood pressure.

Current smokers are 7.6 times more likely to have an AAA than nonsmokers. The prevalence of AAAs among first-degree relatives of patients with AAAs is 15-29%, compared to 2% among relatives of controls. The presence of diabetes, a common underlying disease believed to cause or promote other vascular disease states, is inversely related to the presence of AAA.

Aortic dilatation and aneurysms occur in a minority of patients with Turner syndrome and can result in pre­mature death. In a review of 67 cases of Turner syndrome and aortic dilatation, 3 patients (4%) had severe descend­ing aortic dilatation. Aortic aneurysms occur in 10-48% of patients with Takayasu’s arteritis, with descending thoracic and thoracoabdominal aortic aneurysms being more common than proximal aortic and isolated infrare-nal aneurysms. Autosomal dominant polycystic kidney disease may be associated with ruptured AAAs.

     Some studies have asserted that the size of an aneurysm correlates with its rate of growth over time. Howev­er, a large, population-based cohort study of 176 patients in Rochester, Minnesota found no correlation between aneurysm size and growth rate. The vast majority of aneurysms expand at a rate of 0.2-0.3 cm/year, with only 20% of aneurysms expanding faster than 0.4 cm/year.

     In general, the larger the abdominal aneurysm, the greater the risk of rupture. Additional risk factors for rupture include hypertension, underlying chronic obstructive pul­monary disease (COPD), diameter exceeding 6 cm in men and 5 cm in women, local outpouchings, termed “blebs” or “blisters,” of the aneurysm wall, eccentric or saccular aneurysms, rapid AAA expansion >1 cm per year, a famil­ial history of AAAs in other first-degree relatives, and an increase in diameter over 5 mm in any 6-month period (re­gardless of initial or baseline size). The diameter ratio of the aneurysmal segment to the proximal normal aorta is considered by many surgeons as potentially important in determining rupture risk, but this concept has yet to be validated.

Risk Factors For The Development Of Abdominal Aneurysm:

•          Smoking

•          Hypertension

•          High cholesterol levels

•          Atherosclerotic disease

•          Male gender

•          Increasing age

•          Inflammatory (eg, Takayasu’s arteritis) and infectious (eg, mycotic) aortitis and the presence of an underly­ing aortic dissection

•          Penetrating atherosclerotic ulcer

•          Intramural hematoma

•          Inherited genetic defects of the connective tissue (eg, Turner syndrome, Ehlers-Danlos syndrome)