Consequences of atherosclerosis
- Process
Plaques hurt in two ways: slowly, by narrowing the artery, and suddenly, when they crack and a clot forms on them.
What it is
Atherosclerosis causes disease through slow narrowing (critical stenosis, usually when about 70 % of the lumen is lost, so blood flow cannot rise with demand) and through sudden events. Acute plaque change, meaning rupture or fissuring of the cap, superficial erosion, or bleeding inside the plaque, exposes thrombogenic material and leads to a thrombus that may block the artery. Plaque material and clot can embolise downstream, and in the aorta the thinned media allows aneurysms.
Structure
- Ruptured plaque: broken cap with plaque contents protruding into the lumen and an overlying platelet-fibrin thrombus.
- Cholesterol embolus: needle-shaped empty clefts (cholesterol dissolved during processing) in small arteries, with giant cells.
Step by step
- A plaque grows slowly; the artery first remodels outward and the lumen is preserved.
- Once the lumen narrows enough, flow cannot rise with demand: ischemia with effort.
- Inflammation thins the cap; stress fissures or ruptures it, or the endothelium over it erodes.
- Tissue factor and collagen in the plaque meet blood; platelets aggregate and a thrombus forms.
- A partial thrombus causes unstable ischemia; a complete one causes infarction.
- The thrombus organises or plaque fragments embolise; repeated cycles enlarge the plaque.
Where atherosclerosis strikes and what it causes
| Territory | Lesion | Disease |
|---|---|---|
| Coronary arteries | Stenosis, rupture with thrombus | Angina, myocardial infarction, sudden death |
| Carotid and cerebral arteries | Stenosis, ulcerated plaque with emboli | Transient ischemic attack, ischemic stroke |
| Mesenteric arteries | Ostial stenosis, thrombosis | Intestinal angina, mesenteric infarction |
| Arteries of the legs | Stenosis, thrombosis | Claudication, critical limb ischemia, gangrene |
| Abdominal aorta | Medial thinning under plaques | Abdominal aortic aneurysm |
| Renal arteries and small vessels | Ostial stenosis, cholesterol emboli | Renovascular hypertension, atheroembolic kidney disease |
Clinical notes
- Most myocardial infarctions start on plaques that were only moderately stenotic, which is why stress tests miss many people at risk.
Test yourself
Think of the answer, then tap the question to see it.
At roughly what degree of narrowing does a plaque cause ischemia on exertion?
Around 70 % of the lumen (critical stenosis); at that point flow cannot increase with demand.
What is the commonest event that turns a plaque into an acute coronary syndrome?
Rupture or fissuring of the fibrous cap with thrombosis on the exposed core; erosion is the second mechanism.
What does a cholesterol embolus look like under the microscope?
Empty needle-shaped clefts in small arteries, left where the cholesterol crystals dissolved, often with a giant-cell reaction.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Atherosclerosis | Arteriosclerosis | MedlinePlus (MedlinePlus, US National Library of Medicine, 2025); Coronary Artery Disease | CAD | MedlinePlus (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.