Aneurysm diameter is an important risk factor for rupture. In general, AAAs gradually enlarge (0.2-0.8 mm/year) and eventually rupture. Hemodynamic factors play an important role. Areas of high stress have been found in AAAs and appear to correlate with the site of rupture. Computer-generated geometric models have demonstrated that aneurysm volume is a better predictor of areas of peak wall stress than aneurysm diameter. This may have implications for determining which AAAs require surgical repair.
AAA rupture is believed to occur when the mechanical stress acting on the wall exceeds the strength of the wall tissue. Wall tension can be calculated by applying Laplace’s law, as follows:
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P × R/W
where P is the mean arterial pressure (MAP), R is the radius of the vessel, and W is the thickness of the vessel wall. AAA wall tension is a significant predictor of pending rupture. The actual tension in the AAA wall appears to be a more sensitive predictor of rupture than aneurysm diameter alone. For these reasons, the clinician may wish to achieve acute blood pressure control in patients with AAA and elevated blood pressure.
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Radiograph shows calcification of abdominal aorta. Left wall is clearly depicted and appears aneurysmal; however, right wall overlies spine.
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On radiography, lateral view clearly shows calcification of both walls of abdominal aortic aneurysm, allowing diagnosis to be made with certainty.
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CT demonstrates abdominal aortic aneurysm (AAA). Aneurysm was noted during workup for back pain, and CT was ordered after AAA was identified on radiography. No evidence of rupture is seen.
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Arteriography demonstrates infrarenal abdominal aortic aneurysm. This arteriogram was obtained in preparation for endovascular repair of aneurysm.
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Lateral arteriogram demonstrates infrarenal abdominal aortic aneurysm. Demonstration of superior mesenteric artery, inferior mesenteric artery, and celiac artery on lateral arteriogram is important for complete evaluation of extent of aneurysm.
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Arteriogram after successful endovascular repair of abdominal aortic aneurysm.
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Ultrasonogram from patient with abdominal aortic aneurysm (AAA). This aneurysm was best visualized on transverse or axial image. Patient underwent conventional AAA repair.
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MRI of 77-year-old man with leg pain believed to be secondary to degenerative disk disease. During evaluation, abdominal aortic aneurysm was discovered.
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Age is risk factor for development of aneurysm.
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Inflammation, thinning of media, and marked loss of elastin.
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Pulsatile abdominal mass.
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Aneurysm with retroperitoneal fibrosis and adhesion of duodenum.
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Aortic endoprosthesis (Cook aortic and aortobi-iliac endograft).
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Endoaneurysmorrhaphy
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Endovascular grafts.
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Atheroemboli from small abdominal aortic aneurysms produce livedo reticularis of feet (ie, blue toe syndrome).
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Enhanced spiral CT scans with multiplanar reconstruction and CT angiogram.
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Angiography is used to diagnose renal area. In this instance, endoleak represented continued pressurization of sac.
