Why is the abdominal aortic aneurysm more common?

Not sure: We are not sure why this is the case. The most widely accepted theory is that aaas arise from an inflammatory process related to atherosclerosis. The inflammatory process is believed to degrade the elastin in the wall of the aorta, thereby weakening it. We do not produce elastin as adults. Why this process happens most often in the abdominal aorta is not clear.

Less wall elastin : The aorta, the main artery that delivers blood from the chest to the belly, has a protein known as elastin in its wall. Smoking and COPD affect biochemistry destroying elastin, leading to weakening in the wall causing it to bulge out forming an aneurysm. Why most common in abdomen? Cause elastin layer is thickest in chest thins at renal arteries in abdomen - no surprise they often form there 1st!