Atherosclerosis of the Aorta
The most important disease of the vascular system, atherosclerosis, affects the aorta as well as the smaller arteries. Yet the consequences of atherosclerotic disease in the aorta are less pronounced than in the arteries supplying blood to the heart, brain, or kidneys, which may suffer serious damage because of occlusion. Atherosclerotic changes in the intima (inner lining) of the aorta are similar to those in the intima of the smaller arteries but rarely grow large enough to interfere with the blood flow in this vessel. Changes in the aortic intima have no direct effect on its function, although atherosclerotic ulcers may become a source of thrombi, which could break loose and cause emboli in distant organs.
A special situation exists when atherosclerosis of the intima is combined with arteriosclerotic abnormalities of the aorta. The media (middle layer) of the aortic wall can then be weakened to the point that the pressure in the aorta causes a ballooning of a portion of its wall into an aneurysm.