Aortic+Aneurysms

-An **Aneurysm** is an abnormal localized dilation of a blood vessel. Can occur in different types of arterial vessels, but they are most common in the aorta. Once initiated, the aneurysm grows larger as the tension in the vessel wall increases. As it increases in diameter, the tension in the wall of the vessel increases in direct proportion to its increased size. If untreated à it may rupture bc of increased tension. Even an unruptured aneurysm can cause damage by exerting pressure on adjacent structures. -Abdominal aortic aneurysms: usually develop after age 50 yrs. -More in men than women -Atherosclerosis à major cause of abdominal aortic aneurysms -Other factors: Hypertension, genetics (Marfan syndrome, genetic defects). -Most commonly located below level of the renal artery à involve bifurcation of the aorta and proximal end of common iliac arteries à can involve any part of the vessel circumference (saacular) or extend to involve the entire circumference (fusiform). -**Causes: -2 Most common causes: 1. Atherosclerosis: most frequent etiology of aneurysms--causes arterial thinning thru destruction of the vessel media that occurs 2ndary to plaque formation in the media. Atherosclerotic aneurysms occur most often in the abdominal aorta, but the common iliac artery, the aortic arch and the descending aorta can be involved. 2. Degeneration of vessel media -Other causes: congenital defects, trauma, infections. Infections of a major artery that weakens the vessel wall gives rise to mycotic aneurysms--they can originate fr. embolization or arrest of a septic embolus at some point in a vessel, ususally the complication of infective endocarditis; as an extension of an adjacent suppurative process; or from circulating organisms that infect the arterial wall. In the past, syphilis was a common cause of thoracic aneurysms. ** -Most à asymptomatic -B/c it is of arterial origin, a pulsating mass may be 1st sign of evidence à may be discovered during routine exam or pt. may complain -Calcification: frequently exists on the wall of aneurysm à may be detected during abdominal radiologic exam. Pain may be present and varies fr. mild mid-abdominal or lumbar discomfort to severe abdominal and back pain. -As aneurysm expands à may compress lumbar nerve roots, causing lower back pain that radiates to the posterior aspects of the legs -Aneurysm may extend to and impinge on renal, iliac, mesenteric or vertebral arteries that supply the spinal cord à may also cause erosion of vertebrae. -Stasis of blood favors thrombus formation along the wall of the vessel, and peripheral emboli may develop, causing symptomatic arterial insufficiency.
 * __-Aortic Aneurysms__**
 * -Clinical Features:**