Describe site of fibrous atheromatous plaques
Prominent at branching points of major arteries, in severe disease becomes confluent.
In aorta most commonly, abdominal aorta
Muscular arteries, coronary, carotid, vertebrobasilar, mesenteric, renal & iliofemoral arteries.
Describe microscopic features of fibrous atheromatous plaques
- Fibrous cap, under endothelium, consisting of dense collagen, scattered SM & macrophages
- Lipid zone: foam cells, extracellular lipid, cholesterol crystals & necrotic debris.
- Peripheral zone shows neovascularization:
Media deep to plaque is attenuated & fibrosed
Different plaquescontsin varying amount of 3 layers
Dystrophic calcification is common in lipid zone
Mention & explain the acute plaque changes
- Rupture/fissuring, exposing thrombogenic plaque content and causing acute catastrophic thrombosis.
- Erosion/ulceration, expsoing thrombogenic BM, causing thromboses
- Atheroembolism, rupture can discharge debris into blood, producing microemboli
- Hemorrhage into atheroma, expansion of size and occlusion of artery
Mention effects and complications of atherosclerosis
- The aorta is weakened with dilatation, atheromatous aneurysm. Subsequent mural thrombosis may iccur with detachment and embolic manifestions
- The medium sized vessels, narrowing of lumen leading to ischemia, complete occlusion leading to infarction.
Compare stable and unstable plaques with respect to effect & composition
Stable: chronic ischemia by narrowing of vessels. Dense fibrous cap, minimal lipid deposition, little inflammation.
Unstable: dramatic fatal ischemic complications as acute plaque ruptue, thrombosis or embolization. Thin caps, large lipid cores & dense inflammatory infiltrates.
Describe site & microscopic features of fatty streaks
Site: maximally around aortic valve ring & thoracic aorta
Microscopic: they consist of lipid filled foamy macrophages
What is the stain of fatty streaks?
Sudan III
Mention causes of endothelial injury
Hypertension, aging process, virus, stress, cigarette smoking, immune complex deposition.
Describe pathogenesis of atherosclerosis
- ENdothelial injury leads to adhesion of monocytes which enter the intima & imbibe LDL
- LDL is oxidized which is toxic to endothelium leading to edothelial cell loss, exposure of subendothelium, platelet adhesion & microthromi
- Accumulation of lipoproteins in vessel wall
- Platelets release mitogenic factors causing migration of smooth muscle cells into intima and their proliferation
- Activated smooth muscle and macrophages release PDGF, TGF-alpha, TNF, FGF (mitogenic)
- The smooth muscke cells, macrophages & matrix accumulate LDL from plasma
Describe how the response-to-injury theory views atherosclerosis
Chronic inflammatory response of arterial wall to endothelial injury
Mention constituational risk factors of atherosclerotic arterial disease
- Increasing age
- Sex
- Family history (under 55 yrs)
- Lack of physical exercise & stressful patterns of life
Mention potentially controllable risk factors of atherosclerotic arterial disease
- Hyperlipidemia
- Hypertension
- Diabetes mellitus
- Cigarette smoking
Increase in ….., inc risk of athero, while inc …. dec risk.
LDL
HDL
Arteriosclerosis affects ….
Small arteries & arterioles
What is Mönckeberg medial calcific sclerosis?
Calcific deposits in media of muscular art
Define an Atheromatous plaque (gross appearance)
It consists of a raised lesion with a soft yellow core (mainly cholesterol & cholesterol esters) covered by a firm white fibrous cap
Atherosclerosis is manifested as …..&…..
Coronary artery disease
Carotid atherosclerotic disease disease & stroke
Atherosclerosis affects …..
Arge & medium sized arteries
