Vascular Disease 1: Atheroms And Its Complications

Question 0

Arteriolosclerosis definition

Answer 0

Thickening and hardening of an arterioles

Question 1

Arteriosclerosis definition

Answer 1

Thickening and hardening of an artery

Question 2

Atheroma definition

Answer 2

Degenerative disease effecting large and medium arteries
Initially disease of the intima, later effects media
Only occurs in high pressure systems, not venous, rarely pulmonary
Ubiquitous but very mild in young people-> declines with age

Question 3

Role of hypertension in arterio and arterioloscelerosis

Answer 3

Hypertension is the most common cause of thickening and hardening of the small arteries and arterioles
Also a risk factor for Atheroma
Mechanism:
Hypertrophy of the media
Fibroblast thickening of intima
Elastic lamina replication
-> decreased lumen
In arteriolosclerosis-> replacement of wall structures by amorphous hyaline material
-> decrease lumen-> decreased flow-> Ischaemia
->rigidity of vessel wall-> loss of elasticity and contractility-> unresponsive
Problems when demand is increased

Question 4

Atheroma stage 1

Answer 4

Damage to endothelium
Blood lipids (LDL) can enter intima

Question 5

Atheroma stage 2

Answer 5

LDL is taken up by macrophages in the in intima
Proliferation of myointimal cells via growth factor attraction by macrophages
Normal receptor mediated lipid is bypassed by oxidation of LDL-> taken up by receptor independent pathway
Lipid accumulates producing a fatty streak-> visible pale bulge

Question 6

Atheroma stage 3

Answer 6

Macrophages start to release lipid into the intima
Myointimal cells have myofibroblasts properties-> start to secrete collagen
Raised yellow lesion-> lipid plaque
Early damage to elastic lamina and media
Pressure atrophy on muscle layer-> dissolved by proteolytic enzymes

Question 7

Atheroma stage 4

Answer 7

Increased collagen synthesis forms a dense fibrous cap over the plaque
Plaque becomes fiibrolipid-> hard and white
Muscle in media is replaced by collagen-> weakens walls
Endothelium is fragile-> ulcerates exposing collagen with fibrin-> thrombus formation via platelet aggregation

Question 8

Atheroma stage 5

Answer 8

Complicated Atheroma
Free lipid as well as lipid in macrophages
Lipid in intima becomes calcified
Surface of fibrolytic plaque ulcerates
Thinning of media leads to weakness and elasticity

Question 9

Complications of Atheroma, reduction of blood flow through arteries

Answer 9

Enlargement of intima reduces lumen-> decreased blood flow-> Ischaemic damage
Coronary arteries-> angina
Leg arteries-> intermittent claudication
Cerebral and vertebral arteries-> cerebral Ischaemic Events
Tissue may eventually die of hypoxia

Question 10

Complications of Atheroma, predisposition to thrombus formation

Answer 10

Ulceration of fibrous cap-> exposes collagen to blood
Initiates thrombus formation
Thrombus may suddenly occlude small arteries-> coronary or cerbral arteries
Or thrombus May embolism in distal vessels

Question 11

Complications of Atheroma, bleeding into a plaque

Answer 11

Breakdown of fibrous cap-> blood seeps in-> dissects centre of plaque-> plaque balloons-> occlusion
Or blood undergoes thrombosis in plaque

Question 12

Complications of Atheroma, weakening of vessel walls and aneurysm

Answer 12

Muscle and elastic fibres of media replaced by collagen-> media becomes incompetent-> stretches and becomes thin and weak-> dilation of artery
Most common in abdo aorta

Question 13

Aneurysm

Answer 13

Abnormal permanent focal dilation of an artery
Abdo most common
Also
Syphilitic
Aortic dissection
Berry
Mycotic-> mostly caused by endocarditis, bacterial septicaemia

Question 14

Pathogenesis of Atheroma, thrombogenic hypothesis

Answer 14

Thrombus is incorporated into intima of vessels

Lipid derived from platelet membranes and cells stimulated to proliferate by platelet derived growth factors

Question 15

Pathogenesis of Atheroma, clinal proliferation hypothesis

Answer 15

Obese ration that smooth muscle cells in plaques are derived from one clone of cells
-> caused by a primary abnormality in cell growth

Question 16

Pathogenesis of Atheroma, lipid insudation hypothesis

Answer 16

LDLs taken up by intima

Become chemically oxidised to act as toxic, pro inflam and chemotactic factors

Question 17

Pathogenesis of Atheroma, response to injury hypothesis

Answer 17

Atheromatous plaque is response to chromic low grade injury to endothelium
Metabolic disturbances to endothelial cells (haemodynamic stress and toxic effects of LDL)-> platelet adhesion, diffusion of plasma protiens, and migration of monocytes in to the intima of arteries
Platelets release PDGF-> proliferation of intimal smooth muscle-> produces excesse collagen and elastin in to intima

Question 18

Risk factors for Atheroma, constitutional

Answer 18

Increases with age
More common in men than women
Familial traits

Question 19

Hard Risk factors for Atheroma

Answer 19

Hyperlipidemia-> risk increases as cholesterol increases
High HDL-> reduces the risk
Hypertension 
Diabetes mellitus-> hypercholesterolemia
Cigarette smoking

Question 20

Soft risk factors for atherosclerosis

Answer 20

Exercise-> decreases risk
Overweight
Stress and personality