Pathology of Aortic Aneurysm and Aortic Dissection

Abstract

Abdominal aortic aneurysms are very common in elder population and their rupture is the important cause of death in the western countries. Atherosclerotic abdominal aneurysms result from a weakening of the aortic wall by the extension of the disease into the media. Destruction of elastic fibers and medial atrophy are prominent in the affected aortic wall. Recent studies demonstrated that molecular pathogenesis of aortic aneurysm was explained by the activation of matrix metalloproteinase. In contrast, cystic medial necrosis with fragmentation of elastic fibers is the most important histological feature for ascending aortic aneurysm. Atherosclerosis is important for the etiology of descending aortic aneurysm and its histological features are similar to that of abdominal aortic aneurysm. Cystic medial necrosis is also important for the etiology of aortic dissection. Close relationship between aortic dissection and diseases such as hypertension, Marfan syndrome and congenital bicuspid aortic valves are well known. Re-expansion of aneurysm due to the endoleak after stent-graft deployment is critical problems. Our autopsy case of stent-graft deployment for aortic aneurysm revealed mural thrombi formation at the surface of native aortic wall.