Abdominal Aortic Aneurysm
Progressive weakening and dilatation of the abdominal aortic wall beyond 3cm, which enlarges silently under rising wall tension until it ruptures, a catastrophic emergency defined by pain, hypotension and a pulsatile mass.
First principles
An aneurysm is a wall that has lost its structural integrity
Proteolytic destruction of elastin and collagen in the aortic media (driven by atherosclerosis, smoking and hypertension, and sometimes an underlying connective tissue predisposition) weakens the vessel wall so that it can no longer resist the outward force of arterial pressure. The wall stretches, and once dilated beyond about 3cm it is defined as an aneurysm. This is a structural failure, not a blockage, which is why aneurysmal disease and occlusive atherosclerotic disease, though they share risk factors, behave so differently.
Educational content pending clinical review. Not medical advice.