Calcification of the abdominal aorta is caused by the presence and subsequent calcification of atheromatous plaques in the aorta, which form by accumulation of fatty deposits in the blood vessels. The calcification is not actually of the artery itself, but these plaques that are formed there by atheroma.
The atheromatous plaques that calcify and cause the rigidness of the abdominal aorta appear on the intimal surface of the aorta. The intimal surface is the innermost membrane of the blood vessel, where the atheromatous plaques form and begin calcification. In this way, the calcification of the abdominal aorta is often seen as a type of atherosclerosis. This differs from arteriosclerosis because arteriosclerosis occurs in the tunica media membrane.
Atheromatous plaques are formed by fatty deposits within the blood vessels indicative of atherosclerosis. The primary factors for the formation of these plaques is hypercholesterolemia, inflammation and endothelial injury by disease, and toxins such as those from chronic cigarette smoking. Chronic endothelial stress not only induces LDL cholesterol oxidation but also the expression of adhesion proteins such as VCAM-1, ICAM-1 and chemokines, causing large-scale aggregation and plaque formation. As these calcify, they cause rigidness in the endothelial lining of the aorta and other blood vessels.
The calcification of the abdominal aorta and the resultant atherosclerosis have also been linked to osteoporosis, a study by the AHA reports. The risk and presence of cardiovascular disease and other lifestyle factors, such as obesity, cigarette smoking, alcohol intake and level of exercise, have a significant influence on the calcification of the abdominal aorta, according to the U.S. National Library of Medicine. Reduced bone density of the lumbar vertebrae and the presence of large fat masses have also been linked to the calcification of the abdominal aortic wall, an NIH study suggests.