Session 7 - Atheroma

Question 1

What is atheroma?

Answer 1

Accumulation of intracellular and extracellular lipid in the intima and media of large and medium sized arteries

Question 2

What is atherosclerosis?

Answer 2

Thickening and hardening of arterial walls as a consequence of atheroma

Question 3

What is arteriosclerosis?

Answer 3

Thickening of artery walls due to hypertension or diabetes mellitus

Question 4

What are the different types of atheroma macroscopically?

Answer 4

The fatty streak
The simple plaque
The complicated plaque

Question 5

Features of fatty streak atheroma

Answer 5

lipid deposits in intima

yellow, slightly raised

Question 6

Features of the simple plaque

Answer 6

white, raised, irregular outline, widely distributed, enlarge and coalesce

Question 7

Features of the complicated plaque

Answer 7

Thrombosis
Heamorrhage into plaque
Calcification
Aneurysm formation

Question 8

Common sites of atheroma?

Answer 8

Aorta - especially abdominal
Coronary arteries
Carotid arteries
Cerebral arteries
Leg arteries

Question 9

What are the early microscopic features of atheroma?

Answer 9

proliferation of smooth muscle cells
accumulation of foam cells (macrophages with lipid)
extracellular lipid

Question 10

What are the later microscopic features of atheroma?

Answer 10

fibrosis
necrosis
cholesterol clefts
maybe inflammatory cells
disruption of internal elastic lamina -> media
ingrowth of blood vessels
plaque fissuring (blood pressure shearing force)

Question 11

Clinical effects of atheroma?

Answer 11

Ischaemic heart disease
-> death
-> MI
-> angina pectoris
-> arrhytmias -> VF -> death
-> cardiac failure
Cerebral ischaemia
-> transient ischaemic attack (mini stroke)
-> cerebral infarction (stroke) -> Rx carotid endarterectomy
-> multi-infarct dementia (tiny infarcts)
Mesenteric ischaemia
-> ischaemic colitis ( atheroma in superior mesenteric artery)
-> malabsorption
-> intestinal infarction
Peripheral vascular disease
-> intermittent claudication
-> leriche syndrome -> iliac arteries, pain in buttocks
-> ischaemic rest pain
-> gangrene

Question 12

Main cause of atheroma?

Answer 12

Hyperlipidaemia - high plasma cholesterol (LDL)

Question 13

Signs of familial hyperlipidaemia?

Answer 13

corneal arcus
tendon xanthomas
xanthelasma

Question 14

Pathogenesis of atheroma?

Answer 14

Endothelial injury due to:
raised LDL
toxins (cigarette smoke)
hypertension
haemodynamic stress

Question 15

What does endothelial injury cause?

Answer 15

platelet adhesion, PDGF release, smooth muscle cell proliferation and migration -> matrix material
insudation of lipid, LDL oxidation
migration of monocytes into intima -> foam cells secrete cytokines -> further SMC stimulation, and recruitment of other inflammatory cells

Question 16

Prevention of atheroma?

Answer 16

no smoking
reduced fat
treat hypertension
less alcohol
regular exercise

Question 17

What cells are involved in atheroma? (6)

Answer 17

endothelial cells
platelets
smooth muscle cells (SMC)
macrophages (foam cells)
Lymphocytes
Neutrophils

Question 18

What do endothelial cells do?

Answer 18

Haemostasis
have altered permeability to lipoproteins
secretion of collagen
stimulate SMC

Question 19

What do platelets do?

Answer 19

Haemostasis

stimulate SMC via PDGF

Question 20

What do smooth muscle cells do?

Answer 20

take up LDLs and other lipid to form foam cells

synthesise collagen and proteoglycans

Question 21

What do macrophages do?

Answer 21

oxidise LDLs
Take up lipids to become foam cells
secrete proteases (modify matrix)
stimulate proliferation and migration of SMC

Question 22

What do lymphocytes do?

Answer 22

TNF may affect lipoprotein metabolism

stimulate proliferation and migration of SMC

Question 23

What do neutrophils do?

Answer 23

secrete proteases leading to continued local damage and inflammation

Question 24

What pathogens are associated with atheroma?

Answer 24

Chlamydia pneumoniae
Helicobacter pylori
Cytomegalovirus

Question 25

Risk factors for atheroma? (13)

Answer 25

Age
Gender
Hyperlipidaemia
Cigarette smoking
Hypertension
Diabetes mellitus
Alcohol
Infection
Lack of exercise
Obesity
Soft water
Oral contraceptives
Stress and personality type