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Atherosclerosis - Coggle Diagram
Atherosclerosis
Pathogenesis
Affects arteries only
Medium/large arteries
Greater than 2mm diameter
Usually start at branch points
Due to turbulence and increased sheer/stress
Common locations
Abdominal aorta
Coronary arteries
Ilio-fem-popliteal
Carotid arteries
Circle of Willis
Disease of the intima
Involves smooth muscle cells of media
Fatty streak
Yellow flat spots < 1mm
Lipid foam cells
Don't disturb blood flow
Initial lesion
Response to injury hypothesis
Chronic inflammatory/healing response to endothelial injury
Endothelial damage (injury)
Enhanced expression of cellular adhesion molecules on endothelium
Monocytes adhere and enter wall
Endothelial cells and monocytes (macrophages) oxidise lipids (Free radicals)
Oxidized lipids taken up by macrophages
Foam cells formed
Reduced NO levels = early sign of endothelial damage
Platelet adhesion
Increased thrombogenicity
Increased LDL permeability
LDLs enter
Growth factors secreted by macrophages/platelets/endothelium/VSMCs
Myointimal cells proliferate
Macrophages + VSMCs migrate into intima
VSMCs in intima synthesise ECM + collagen
Fibrous cap
Activated macrophages
Recruite more macrophages
Produce...
Oxygen free radicals
Aggrevate lipid oxidation
Growth factors
Factors that induce VSMC death
Slow build-up over time but sudden/acute complications
Interaction of lipoproteins/lipids, macrophages, T lymphocytes + endothelium and VSMCs
Extracellular matrix formation
Lesion progression (from fatty streak)
Angiogenesis + mineralization
Atheromatous plaque structure
Fibrous cap
Core: cholesterol + necrotic debris + foam cells
Clinical Manifestations
Acute plaque change
Plaque rupture/fissuring
Thrombosis of coronary artery
Haemorrhage into plaque
Sudden expansion
Infarction (e.g. MI)
Erosion/ulceration
Thrombosis
Occlusion
Growth of plaque
Embolus from thrombus
Vasoconstriction
Local factors
Dilation (due to structural weakness)
Aneurysm
Atherosclerotic stenosis
Coronaries
Angina
Chronic ischaemic heart disease
Mesenteric arteries
Ischaemic bowel
Circle of Willis
Ischaemic encephalopathy
Stroke
Lower limbs
Intermitten claudication
Peripheral vascular disease
Aorta
Abdominal aortic aneurysm
Epidemiology
Incidence increases with age
Risk factors
Modifiable
Dyslipidaemia
Raised LDL
Decreased HDL
High BP
Dysglycaemia
Cigarrette smoking
Fixed
Age
Gender
Male
Post-menopausal female
Genetics
Family history
Lipoprotein abnormalities
E.g. familial hypercholesterolaemia
