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Inflammatory aortic aneurysm (IAA), also known as Inflammatory abdominal aortic aneurysm (IAAA), is a type of abdominal aortic aneurysm (AAA) where the walls of the aneurysm become thick and inflamed. Similar to AAA, IAA occurs in the abdominal region.〔Hellmann DB, Grand DJ, Freischlag JA. Inflammatory Abdominal Aortic Aneurysm. JAMA. 2007;297(4):395-400. doi:10.1001/jama.297.4.395〕 IAA is closely associated and believed to be a response to and extensive peri-anuerysmal fibrosis,〔Ishizaka, Nobukazu, Koichi Sohmiya, Masatoshi Miyamura, Tatsuya Umeda, Motomu Tsuji, Takahiro Katsumata, and Tetsuro Miyata. "Infected Aortic Aneurysm and Inflammatory Aortic Aneurysm—In Search of an Optimal Differential Diagnosis." Journal of Cardiology 59.2 (2012): 123-31. Web.〕 which is the formation of excess fibrous connective tissue in an organ or tissue in a reparative or reactive process IAA accounts for 5-10% of aortic aneurysms. IAA is occurs mainly in a population that is on average younger by 10 years than most AAA patients. Some common symptoms of IAA may include back pain, abdominal tenderness, fevers, weight loss or elevated Erythrocyte sedimentation rate (ESR) levels. Corticosteroids and other immunosuppressive drugs have been found to decrease symptoms and the degree of peri-aortic inflammation and fibrosis 〔 ==Mechanism== In general, an aneurysm is bulge that can occur in blood vessels or sometimes in the heart itself. In the case of IAA, this type of aneurysm is localized in the aortic artery, which is the artery that carries oxygenated blood from the heart to the rest of the body. . This location is ideal for aneurysms to develop based upon the high stress and pressure from blood circulation. Fibrosis, a stiffening of the muscle, may occur due to the exposure to stress and blood pressure. In the development of the fibrosis an autoimmune response may occur which in the area causing the "inflammation." This inflammation is what gives IAA the characteristic thickened walls of the aneurysm. All types of abdominal aortic aneurysms occur in the part of the aorta that passes through the middle to low abdomen. Thoracic aortic aneurysms occur on the aorta as it passes through the chest cavity. These are less common than abdominal aneurysms. Small aneurysms generally pose no threat. However, aneurysms increase the risk for: * Atherosclerotic plaques to form at the site of the aneurysm, which causes further weakening of the artery wall. * blood clots may form at the site and dislodge, increasing the chance of stroke * Increase in the size of the aneurysm, causing it to press on other organs, which may cause pain. * Aneurysm may also rupture. It is fragile and may burst under stress. The rupture of an aortic aneurysm is a catastrophic, life-threatening event. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Inflammatory aortic aneurysm」の詳細全文を読む スポンサード リンク
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