Abdominal aortic aneurysm—2003: What we know, what we don't know—A review

Abstract

Abdominal aortic aneurysm is a significant cause of morbidity and mortality. Although descriptions of aneurysmal disease date back to 2000 BC, scientific approaches to understanding the pathogenesis and management of abdominal aortic aneurysms date back less than 200 years. Abdominal aortic aneurysms account for two-thirds of large series of aneurysmal disease. The incidence of abdominal aortic aneurysm ranges from 1–16%. The highest incidences occur in the first-degree relatives of individuáls with an abdominal aortic aneurysm. Higher incidences are identified in white males, in patients with chronic obstructive lung disease, and in smokers. Pathologically identified is the destruction of medial and adventitial elastin and collagen as well as destruction of medial smooth muscle cells. The infiltration by lymphocytes and macrophages leads to release of cytokines and matrix metalloproteinases. Inherited aspects that have been identified involve antitrypsin deficiency. The role of simple screening by ultrasound or CT has proved cost effective to identify patients with abdominal aortic aneurysm and to follow progression. In an effort to prevent the high morbidity and mortality costs associated with ruptured abdominal aortic aneurysm, several management routes have emerged. The indications for management include size as well as associated conditions that increase risk of rupture. The risks and complications of any management approach are balanced against the risks of rupture and against the risks of management at a stage of increased physiological risks with increasing age. Improvements in mortality and morbidity with open surgical repair are the result of improved surgical and anesthetic techniques. Beginning in 1990 the endovascular repair of abdominal aortic aneurysms has proceeded. The key factors involved in successful use have included efforts to achieve proximal and distal endograft fixation and sealing with the aortic wall at the proximal neck and distally within the aorta or iliac arteries. The experience and attributes of available prostheses are presented. The nature of endoleaks and their management are reviewed. The possible pharmacologic approaches to prevent aneurysm progression include the use of tetracyclines and COX-2 inhibitors to inhibit matrix metalloproteinase 9, the use of ACE inhibitors to suppress elastase activity and statins to decrease the inflammatory process. Although many questions regarding abdominal aortic aneurysms have answers, many more await answers.