Arteriosclerosis
- medial sclerosis
- arteriolarsclerosis - arterioles (<0.3mm diameter) - seen in malignant hypertension (thick intima)
- atherosclerosis - larger arteries (most often aorta) also coronary arteries, cerebral arteries, etc.
- deposition of atheromas common at bifurcation of arteries (favored by turbulent flow)
- microscopic appearance - all 3 layers are affected
- media - loss of smooth muscle, replaced with collagen and ground substance
- adventitia - fibrous thickening, inflammation
- intima - deposition of atheromatous plaque - receptors for LDL catch LDL in circulation. Monocytes also enter intima (renamed macrophages once in intima). macrophages eat LDL and become "foam cells". fibrous cap formed.
- emboli - from broken plaques.
- aneurysm
- dissecting - tear in intima = double barrelled blood vessel - seen in Marfan's
- arherosclerotic - > 5cm at risk for rupture
- coronary artery atherosclerosis - normally epicardial arteries involved (not intramusclular arteries)
- supply/demand properties (e.g., shovelling snow MIs)
- MI common with 70% narrowing of coronary artery (esp. if narrowing is acute)
- enlarged heart dangerous - one capillary serves one myocyte
- damage to muscle takes days to weeks to appear; scarring occurs after 2 months
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