Understanding Atherosclerosis Formation and Risks

Atherosclerosis Revision Sheet

1. 📌 Essentials (Key Facts)

• Atherosclerosis = formation of fatty plaques (atheromas) in medium-large arteries.
• Deposits are mainly LDL cholesterol beneath the endothelium.
• Lesions start as fatty streaks in ages 10-20; symptomatic disease occurs after 35-40 years.
• Major risk factors: high LDL, hypertension, smoking, diabetes, age, obesity.
• Pathogenesis involves endothelial dysfunction, LDL oxidation, foam cell formation, and fibrous cap development.
• Plaques are classified as stable (collagen-rich) and unstable (lipid-rich).
• Critical stenosis causing symptoms: >70-75% narrowing.
• Plaque rupture exposes necrotic core, causing thrombosis and potential occlusion.
• Clinical syndromes: angina, MI, stroke, claudication, gangrene.
• Atheromatous deposits lead to ischemia in heart, brain, lower limbs.

2. 🧩 Key Structures & Components

• Endothelium — lines arteries, initial site of dysfunction.
• LDL cholesterol — main lipoprotein involved in plaque formation.
• Foam cells — macrophages laden with oxidized LDL, form fatty streaks.
• Vascular smooth muscle cells (VSMC) — migrate and produce collagen in fibrous cap.
• Fibrous cap — collagen-rich layer over necrotic core, stabilizes plaque.
• Lipid/necrotic core — consists of dead foam cells, cholesterol crystals, cellular debris.
• Plaque types — stable vs unstable based on composition.
• Thrombus — clot formed upon cap rupture.

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