ABSTRACT
The human aorta enlarges with increasing age and also with increasing atherosclerotic plaque. While both the thoracic and abdominal aortas enlarge with age, abdominal aortic enlargement is more prominently influenced by the amount of atherosclerotic plaque. Since the abdominal aorta is much more prone to athero sclerosis than the thoracic aorta, this may explain the particular propensity for aneurysms to develop in the infrarenal aorta. The human superficial femoral artery also enlarges with increasing atherosclerotic plaque. However, the enlargement response may be restricted and aneurysm formation is much less common than in the abdominal aorta. It is not uncommon to have a twofold enlargement of athero sclerotic arteries as a result o f large intimal plaques, with little or no alteration in lumen cross-sectional area. Failure of adequate arterial dilatation, o f course, will lead to lumen stenosis. Thus, atherosclerosis characteristically causes enlargement of
Fig. 1.2. Enlargement of arteries with increasing atherosclerotic plaque. Enlarge ment can maintain normal or near-normal luminal caliber; when plaque does not exceed 40% of the area encompassed by the internal elastic lamina. Reprinted with permission from Glagov et al. N Engl Med 1987; 316:137.
