atherosclerosis

Picture a clean pipe gradually growing a greasy, crusty lining on the inside until the bore is half its original width. Atherosclerosis is essentially that process happening in arteries: fatty material builds up in the wall, hardens, and narrows the passage over many years.

It begins when cholesterol-carrying particles, especially LDL, lodge in the artery wall and become oxidized. The body's immune cells move in to clear them but instead become foam cells laden with fat, forming a fatty streak. Over time smooth-muscle cells and fibrous tissue wall off this lipid core under a fibrous cap, building a raised plaque. The endothelium — the artery's smooth inner lining — is dysfunctional throughout, fueling inflammation.

Atherosclerosis is systemic: the same process that narrows coronary arteries also affects the brain's arteries (stroke), the legs (peripheral artery disease) and the aorta. It is driven by modifiable factors such as high LDL, smoking, hypertension and diabetes, which is why prevention focuses on these. The danger is not only gradual narrowing but the risk that an inflamed plaque suddenly ruptures.

Atherosclerosis is one form of arteriosclerosis (a broader term for artery stiffening); the plaque-forming, lipid-driven variety is what physicians usually mean in the context of heart disease.