Atheroma

Question 1

Define atheroma

Answer 1

The accumulation of intracellular and extracellular lipid in the tunica intima and media of large and medium sized arteries

Question 2

Define atherosclerosis

Answer 2

Thickening and hardening of arterial walls as a consequence of atheroma

Question 3

What is the difference between atherosclerosis and arteriosclerosis?

Answer 3

Arteriosclerosis is thickening and hardening of arterial walls as a result of hypertension and/or diabetes, not atheroma

Question 4

What are the macroscopic appearances of atheromas?

Answer 4

• Fatty streak (yellow, raised with a regular outline)
• Simple plaque (yellow/white, raised with an irregular outline, can enlarge and coalesce)
• Complicated plaque (calcification of plaque with possible haemorrhage and necrosis, increases risk of thrombosis and aneurysm formation)

Question 5

What are the microscopic appearances of atheromas?

Answer 5

• (early) Accumulation of foam cells and proliferation of smooth muscle cells
• (later) Distribution of internal elastic lamellae, cholesterol clefts, inflammatory response, fibrosis, necrosis, plaque fissuring

Question 6

What are the clinical effects of atheroma?

Answer 6

• Ischaemic heart disease (narrowing of coronary arteries)
• Cerebral ischaemia (narrowing of carotid arteries, infarct may result in transient ischaemic attack/stroke)
• Mesenteric ischaemia (malabsorption, infarct may result in black bowel)
• Peripheral vascular disease (intermittent claudication, buttock claudication, ischaemic rest pain)

Question 7

Describe the unifying hypothesis of the formation of atheroma

Answer 7

• Chronic endothelial injury due to oxidised LDL, smoking or hypertension
• Endothelial injury stimulates platelet adhesion and release of PDGF which attracts macrophages and smooth muscle cells (from TM)
• SMC proliferation and insudation of lipid lead to accumulation of foam cells
• Migration of foam cells into intima (release cytokines which recruit further cells)

Question 8

What are the main factors that relate to the PATHOGENESIS of atheroma? (7)

Answer 8

• Smoking
• Age and gender (males more prone, females protected pre-menopause but catch up post menopause)
• Diabetes
• Hypertension
• Infection (cytomegalovirus, h.pylori, chlamydia pneumoniae)
• Hyperlipidaemia
• Other factors e.g stress, genetic predisposition, obesity, ethnicity

Question 9

How can you prevent atherosclerosis?

Answer 9

• Stop smoking
• Decrease fat intake
• Treat hypertension and/or diabetes
• Aspirin
• Reduce alcohol consumption
• Regular exercise and control of weight

Question 10

What are the clinical presentations of hyperlipidaemia?

Answer 10

• Xanthelasma
• Tendon xanthoma
• Corneal arcus

Question 11

What is type II hyperlipidaemia caused by?

Answer 11

Defect in LDL receptor