Atherosclerosis

Question 1

what is meant by the term arteriosclerosis?

Answer 1

thickening of walls of arteries + arterioles
usually as a result of hypertension or diabetes melitus - often associated with loss of elasticity

Question 2

what are the consequences of arteriosclerosis?

Answer 2

• poor tissue perfusion
• inelastic/weak vessels
• increased risk of thrombus formation

Question 3

what is meant by the term atheroscleorsis?

Answer 3

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

Question 4

What is meant by the term atheroma?

Answer 4

necrotic core of the atherosclerotic plaque
results in thickening and hardening of arterial walls as a consequence of atherosclerosis

Question 5

what are the different theories to explain atherosclerosis?

Answer 5

1. thrombogenic theory
2. insudation theory
3. monoclonal hypothesis
4. reaction to injury hypothesis

Question 6

what are the principles of the thrombogenic theory?

Answer 6

• plaques form by repeated thrombi
• lipid derived from thrombi
• overlying fibrous cap
• inflammation is a secondary effect

Question 7

what are the principles of the insudation theory?

Answer 7

• endothelial injury
• inflammation
• increased permeability to lipid from plasma

Question 8

what are the principles of the reaction to injury hypothesis?

Answer 8

• plaques form in response to endothelial injury
• hypercholesterolaemia causes endothelial damage
• injury increases permeability and allows platelet adhesion
• monocytes penetrate endothelium
• smooth muscles cells proliferate and migrate

Question 9

what are the principles of the monoclonal hypothesis?

Answer 9

crucial role for smooth muscle proliferation
each plaque is monoclonal
represents abnormal growth

Question 10

what cellular events lead to atherosclerotic lesions?

Answer 10

endothelial dysfunction causes:
1. platelet adhesion occurs (platelet derived growth factors are released)
2. smooth muscle cells proliferate and migrate
3. lipids (LDL and cholesterol) cross into the tunica intima
4. monocytes cross into intima

Foam cells secrete cytokines which leads to:
1. further smooth muscle stimulation
2. recruitment of other inflammatory cells

smooth muscle cells:
1. produce matrix material (roof) formed of collagen, elastin + other protiens

Question 11

what are the different components of atherosclerotic plaques?

Answer 11

cells:
* endothelial cells
* platelets
* neutrophils
* macrophages
* leucocytes
* smooth muscle cells

lipid:
* extracellular pools and intracellular foam cells

extracellular matrix:
* collagen
* elastin
* proteoglycans

Question 12

what is the role of endothelial cells in atherosclerotic plaque formation?

Answer 12

• role in haemostasis
• altered permeability to lipoproteins
• produce collagen
• stimulate proliferation + migration of smooth muscle cells

Question 13

what is the role of platelets in atherosclerotic plaque formation?

Answer 13

• role in haemostasis
• stimulate proliferation + migration of smooth muscle cells

Question 14

what is the role of smooth muscle cells in atherosclerotic plaque formation?

Answer 14

• synthesise collagen and proteoglycans

Question 15

what is the role of macrophages in atherosclerotic plaque formation?

Answer 15

• take up oxidised LDL to become foam cells
• secrete proteases which modify matrix
• stimulate proliferation + migration of smooth muscle cells

Question 16

what is the role of lymphocytes in atherosclerotic plaque formation?

Answer 16

releases TNF (tumour necrosis factor) affects lipoprotein metabolism
stimualte proliferation + migration of smooth muscle cells

Question 17

what is the role of neutrophils in atherosclerotic plaque formation?

Answer 17

secrete proteases leading to continued local damage and inflammation

Question 18

what is the microscopic appearance of atherosclerotic plaques?

Answer 18

fatty streak contains:
* proliferation of smooth muscle cells
* accumulation of foam cells
* extracellular lipid

stable/simple plaque contains:
* fibrosis
* necrosis
* cholesterol clefts
* may contain inflammatory cells

unstable/complicated/vulnerable plaque contains:
* disruption of internal elastic lamina
* damage extends into media
* new vessels grow into plaque
* plaque erodes

Question 19

what is the macroscopic appeareance of fatty streak?

Answer 19

lipid deposition, slightly raised yellow area in intima

Question 20

what is the macroscopic appeareance of stable or simple plaque?

Answer 20

raised yellow/white, irregular outline, widely distributed, enlarge and coalsece

Question 21

what is the macroscopic appeareance of a vulnerable or unstable plaque?

Answer 21

yellow and red, irregular, rough, hard and calcified

Question 22

what are the different risk factors for development of atherosclerosis?

Answer 22

• age
• gender
• geography
• smoking
• hypertension
• alcohol
• hyperlipidaemia

Question 23

what are the different interventions to prevent atherosclerotic disease?

Answer 23

• stop smoking
• decrease fat intake
• control hypertension
• increase exercise
• aspirin

Question 24

what are the different interventions to manage atherosclerotic disease?

Answer 24

• weight management
• manage diabetes melitus
• take lipid lowering drugs
• lower alcohol intake

Question 25

what is the affect of atherosclerosis in heart?

Answer 25

• ischaemia
• MI
• arrhythmias
• heart failure
• ischaemic heart disease

Question 26

what is the affect of atherosclerosis in brain?

Answer 26

transient ischaemic attack (TIA)
cerebral infarction (stroke)
vascular dementia

Question 27

what is the affect of atherosclerosis in the GI tract?

Answer 27

• mesenteric ischaemia

Question 28

what is the affect of atherosclerosis in peripheral arteries?

Answer 28

• peripheral vascular disease
• acute limb ischaemia
• intermittent claudication
• ischaemic rest pain

Question 29

what is the affect of atherosclerosis in abdominal aorta?

Answer 29

• aneurysmal formation
• rupture of AAA
• thrombosis and emboli (can cause acute limb ischaemia)