Incidence and pathogenesis of aneurysmal disease of the abdominal aorla.

Abdominal aortic aneurysms (AAAs) are a major cause of illness and death in the United States and abroad. Along with progress in the surgical management of this condition, numerous advances have been made in understanding the pathogenesis of AAAs. Since the time of Scarpa (1804), AAA disease has been associated with, and attributed to, atherosclerotic vessel changes. Excluding patients with Marfan's Syndrome and Ehlers-Danlos type IV diseases, virtually all human AAA specimens contain some degree of atherosclerosis. However, atherosclerotic changes are associated with diverse arteriopathies (ie, aorto-occlusive disease versus AAAs). Over the last 25 years, considerable research has been performed comparing aneurysmal, occlusive, and normal aortae. AAA disease is a unique process with pathogenic mechanisms that may operate independently of atherosclerosis. In this chapter we discuss the incidence of AAA as well as its pathogenesis concerning genetics, molecular biology, biochemistry, and immunology.