Atherosclerosis Flashcards
What is atherosclerosis?
Formation of elevated lesions in tunica intima
What is arteriosclerosis?
Age related change in muscular arteries, thickening and hardening of the walls of arteries
What is the first stage of atherosclerosis?
Fatty streak - yellow linear elevation of intimal lining, consists of lipid-laden macrophages just below endothelium, may disappear, no significance, present in kids, may develop to atheromatous plaque
What is the second stage of atherosclerosis?
Early atheromatous plaque, go and develop to plaque, smooth yellow patches, central lipid core, lipid-laden macrophages
What is the third stage of atherosclerosis?
Fully developed atheromatous plaque, has central lipid core rich in lipids and debris from macrophages, fibrous cap, covered by endothelium, they are highly thrombogenic, can also have calcium depositions where necrotic tissue is present
What are foamy macrophages?
They can be present in fully developed plaque, can form a rim, due to oxidised lipoproteins uptake via special receptors
What are the common sites of plaque formation?
At bifurcation points, where there is turbulent flow
What is complicated atheroma?
established plaque with features such as haemorrhage, plaque rupture/fissuring or thrombosis
What is the biggest risk factor in atherosclerosis?
Hypercholesterolaemia, can be homo or heterozygous, lack of cell LDL receptor
What are other risk factors ?
smoking, hypertension, diabetes mellitus, male, elderly, less strong risk factors include obesity, sedentary lifestyle, low birth weight, low socio-economic status
What is the firth step in development of atheromatous plaque?
endothelial injury, can be caused by haemodynamic disturbance and turbulent flow, or hypercholesterolaemia that increases production of reactive oxygen species that modify the aggregated lipoproteins, then they are taken up by macrophages but they can’t be completely destroyed and format macrophages are formed, they are toxic to endothelium in addition to realising cytokines and growth factors, this is cyclic process
What is the second step in formation of atheromatous plaque?
functional alteration of endothelium by the injury, high permeability for `LDL, increased thrombogenicity, expression of cell adhesion molecules
What is the third step ?
Accumulation of lipoproteins LDL in the walls of blood vessels
What is the fourth stage?
Monocytes adhere to the endothelium, migrate to the intimal layer, phagocytosis and transformation to foamy macrophages
What is the fifth step?
Aggregation of platelets
What is the sixth stage ?
Activated platelets, macrophages release factor that activates smooth muscles
What is the seventh stage?
Smooth muscle cell proliferation, T lymphocytes recruitment, extracellucalr matrix production
What is the eight stage?
lipid accumulation extracellularly and in foamy macrophages
What is the ninth stage?
marcrophages, T lymphocytes, lipid-laden macrophages die by apoptosis and lipids continue accumulating in lipid core
What is the tenth step?
Release of PDGF from activated platelets, macrophages and injured endothelium causes further proliferation of smooth muscles which then produce collagen elastic and mucopolysaccharides that leads to formation of fibrous cap
What is the required stenosis to cause problems ?
around 70%
What are the complications associated with atheromatous plaques?
rupture of plaque, atherothrombotic occlusion and ischaemia, embolus formation
What is the prevention?
Stop smoking, control hypertension, controlling BP, weigh loss, regular exercise, , dietary modification, cholesterol lowering drugs, aspirin
What are external manifestations of atherosclerosis ?
corneal arcus, tendon xanthomata, xanthelesmata
