Experimental techniques and models in the study of the development and treatment of abdominal aortic aneurysm

Background: It is still unclear what initiates aneurysmal dilatation and wh at determines whether or nor an aneurysm will continue to expand and ruptur e. Early detection and operative repair of an abdominal aortic aneurysm (AA A) still remains the only effective means of reducing the high mortality ra te associated with the condition. Endovascular techniques are being develop ed in an attempt to reduce the mortality rate associated with elective repa ir. A variety of animal models and experimental techniques have been descri bed in the investigation of the pathophysiology of AAA and in the developme nt of improved endovascular surgical and pharmacological therapies. This ar ticle discusses these models and techniques, their advantages and some of t he problems encountered in extrapolating experimental findings to the human condition. Methods: This review is based on a search of the Medline database from 1966 to March 1998 using recognized key words and test words. A further search was then conducted on references quoted within selected relevant publicatio ns. Results and conclusion: Treatment of rodent aortas with intraluminal elasta se or periaortic calcium chloride creates reproducible aneurysms that have certain similarities to the human pathology; such aneurysms have been favou red in the investigation of the pathophysiology of aneurysm expansion, Howe ver, these models lack several of the prominent features of the human lesio n, such as atherosclerosis and intraluminal thrombosis. The development of gene knockout mice may lead to a more analogous aneurysm formation, with as sociated atherosclerosis. Many large animal models have been used in the de velopment of endovascular techniques hut, in general, these do not mimic th e human pathophysiology and fail to predict medium- and long-term complicat ions.