An aneurysm is a localized dilatation of a blood vessel at least 1 1/2 to 2 times the normal vessel diameter. Abdominal aortic aneurysms are relatively common, and have been detected in 1.3% to 2.7% of patients 65 to 80 years of age (Blum, et al, 1996; Collins, Araujo, and Lindsell, 1988; Scott, Ashton, and Kay, 1991). A large proportion (up to 50%) of patients with untreated AAAs experience rupture and exsanguination (Johansen, 1995). Ruptured AAAs are the 13th leading cause of death in the US, accounting for more than 15,000 deaths per year (Cronenwett and Sampson, 1995).