atherosclerosis

Question 1

what is atherosclerosis?

Answer 1

• degenerative and inflammatory disease that affects medium and large arteries, causing thickening of arterial wall and loss of elasticity
• lesions formed in the tunica intima aka atheroma

Question 2

risk factors of atherosclerosis

Answer 2

Non-Modifiable
1. Age (older)
2. Gender (male)
3. Family History
4. Genetics
5. Race

Modifiable
1. Hyperlipidaemia
2. Hypertension
3. Diabetes
4. Smoking

Question 3

What is an atheroma?

Answer 3

• plaque consisting of a raised lesion with a soft yellow core of lipid aka necrotic centre covered with a white fibrous cap @ tunica intima

(necrotic centre): cell debris, foam cell, cholesterol crystals, calcium

Question 4

Pathogenesis of Atherosclerosis

Answer 4

1. Injury to Endothelium Cells
   * causes of endothelium injury:
   - hyperlipidaemia
   - hypertension
   - smoking
   - viruses/infections
   etc
2. Blood flow to the injured site is turbulent
   - atherosclerosis tends to occur at areas of bifurcation
3. Presence of lipid in the blood
   - bounded to apolipoprotein
   - lipoproteinaemia (high LDL, low HDL)

outcome of 1+2+3:
- injury to endothelium cells -> increase permeability of endothelial cells + leukocyte adhesion
- monocytes will migrate to the intima layer because it’s attracted to the lipid deposited there
- monocytes turn into macrophages
- macrophages will recruit smooth muscle cells -> forms fibrous cap
- macrophages will engulf the lipids to form foam cells
- smooth muscle cells will synthesise extracellular matrix

Question 5

3 principal components of atherosclerosis are?

Answer 5

1. Smooth muscle cells, T cells, Macrophages
2. Extracellular matrix (collagen)
3. Extracellular and Intracellular Lipids

Question 6

What are the intrinsic factors of a vulnerable (unstable) plaque?

Answer 6

• large lipid core (large necrotic centre), thin fibrous cap
• increase matrix metalloproteinases by macrophages -> degrade collagen and ECM
• decrease tissue inhibitor of metalloproteinases by endothelial cells

Question 7

What are the early signs of atherosclerosis?

Answer 7

Fatty streaks

Question 8

What are the local consequences of atherosclerosis?

Answer 8

1. Thickening of arterial wall -> narrowing of lumen -> poor tissue perfusion -> ischaemia
2. Loss of elasticity -> predisposition to aneurysm formation, rupture and haemorrhage
3. Endothelial changes -> subendothelial layer exposed -> predisposition to thrombosis (secondary clot formation on top of plaque -> embolism)

Question 9

ACUTE plaque change can cause:

Answer 9

MI
Cerebral Infarct
Aortic Aneurysm
Peripheral Vascular Disease

Question 10

CHRONIC plaque change can cause:

Answer 10

Angina (stable)
Bowel Ischaemia
Chronic Ischaemic Heart Disease
Ischaemic Encephalopathy
Intermittent Claudication