Atherosclerosis

Atherosclerosis: Definition & Risks - Hardening Arteries 101

Atherosclerosis: Chronic inflammation forming intimal fibro-fatty plaques (atheromas), causing arterial wall thickening, hardening, and stenosis.

• Key Non-Modifiable Risk Factors:
  • Increasing Age
  • Male Gender
  • Family History
  • Genetic Predisposition
• Key Modifiable Risk Factors:
  • Hyperlipidemia (↑LDL, ↓HDL, ↑Triglycerides)
  • Hypertension (e.g., BP > 130/80 mmHg)
  • Cigarette Smoking
  • Diabetes Mellitus
  • Obesity (BMI ≥ 30 kg/m²)
  • Physical Inactivity
  • Chronic Inflammation (e.g., ↑hs-CRP)

⭐ Hyperlipidemia (especially ↑LDL cholesterol) and cigarette smoking are the two most significant and modifiable risk factors accelerating atherogenesis.

Atherosclerosis: Pathogenesis - Plaque's Evil Plan

• Trigger: Endothelial injury (↑ permeability, leukocyte adhesion).
• Key Events:
  • LDL insudation & oxidation (oxLDL).
  • Monocytes → Macrophages → Foam cells (engulf oxLDL).
  • Smooth Muscle Cell (SMC) migration, proliferation, ECM deposition → Fibrous cap.
  • Necrotic core (lipids, debris) development.
• Outcome: Complex plaque → Calcification, rupture, thrombosis.

⭐ Oxidized LDL (oxLDL) is pivotal, driving inflammation and macrophage transformation into foam cells.

Atherosclerosis: Morphology - Anatomy of Atheroma

• Atheromatous Plaque (Atheroma): Focal intimal thickening; hallmark of atherosclerosis.
  • Key Structural Components:
    • Fibrous Cap: Superficial layer.
      • Composition: Smooth muscle cells (SMCs), dense collagen, elastin, proteoglycans.
      • Cells: Macrophages, T-lymphocytes.
    • Necrotic Core (Lipid Core): Central part, deep to cap.
      • Composition: Cholesterol crystals/esters, necrotic debris, foam cells (lipid-laden macrophages), fibrin, calcium.
    • Shoulder Region: Junction of cap and normal arterial wall; most cellular area.
      • Composition: Macrophages, T-cells, SMCs.
  • Neovascularization: Proliferation of small blood vessels at plaque periphery.

⭐ The shoulder region, rich in inflammatory cells (macrophages, T-cells), is the most common site for plaque rupture, leading to thrombosis and acute coronary syndromes.

Atherosclerosis: Clinical Sequelae - Arterial Blockage Woes

• Coronary Artery Disease (CAD): Angina, Myocardial Infarction (MI).
• Cerebrovascular Disease (CVD): Transient Ischemic Attack (TIA), Stroke.
• Peripheral Arterial Disease (PAD): Intermittent claudication, gangrene.
• Aneurysms: Aortic (abdominal most common), iliac.
• Renal Artery Stenosis: Secondary hypertension, renal failure.

⭐ Most common site for atherosclerosis is the abdominal aorta, followed by coronary arteries, popliteal arteries, internal carotid arteries, and circle of Willis.

• Mesenteric Ischemia: Bowel infarction.
• Sudden cardiac death often due to plaque rupture/thrombosis in CAD.

Atherosclerosis: Prevention Basics - Plaque Defense Tips

• Lifestyle Modification:
  • Diet: ↓Saturated/trans fats, ↑fruits, vegetables, fiber.
  • Exercise: Aerobic, ≥150 min/week.
  • Smoking cessation.
  • Weight management: BMI <25 kg/m².
• Pharmacological:
  • Statins (LDL-C goal <70-100 mg/dL based on risk).
  • Antiplatelet agents (e.g., Aspirin).
  • Blood pressure control (target <130/80 mmHg).

⭐ Statins are first-line for primary and secondary prevention of atherosclerotic cardiovascular disease (ASCVD).

High‑Yield Points - ⚡ Biggest Takeaways

• Most common sites: Abdominal aorta > coronary > popliteal > carotid arteries.
• Initiating event: Chronic endothelial injury/dysfunction.
• Hallmark lesion: Atheromatous plaque (fibrous cap, necrotic lipid core).
• Major modifiable risks: Smoking, hypertension, diabetes, hyperlipidemia (↑LDL, ↓HDL).
• Earliest lesion: Fatty streaks (lipid-laden macrophages/foam cells).
• Key complications: Myocardial infarction, stroke, aortic aneurysms, peripheral vascular disease.