coronary artery disease (overview) Flashcards
when does myocardial ischaemia occur
when there is an imbalance between the supply of oxygen and the myocardial demand
why can coronary blood flow be reduced
- atheroma
- thrombosis
- spasm
- embolus
- coronary ostial stenosis
- coronary arteritis
what can cause a decrease in flow of oxygenated blood to the myocardium
- anaemia
- carboxyhaemoglobulinaemia
- hypotension
what can an increased demand for oxygen cause
- increased cardiac output (thyrotoxicosis)
- myocardial hypertrophy
what is most common cause of coronary artery disease
myocardial ischaemia
what is coronary atherosclerosis characterised by
accumulation of lipid, macrophages and smooth muscle cells in intimal plaques
what plays a critical role in maintaining vascular integrity and homeostasis
vascular endothelium
what happens to an accumulation of oxidised lipoproteins
taken up by macrophages at focal sites within the endothelium to produce lipid-laden foam cells
what do the foam cells look like macroscopically
flat, yellow dots or lines on the endothelium of the artery
what are foam cells known as
fatty streaks
what promotes further accumulation of macrophages
release of cytokines, such as platelet-derived growth factor and transforming growth factor beta by monocytes, macrophages
what does the smooth muscle produce in larger quantities due to plaques
collagen
what are 2 mechanisms of thrombosis
- superficial endothelial injury
- deep endothelial fissuring
what does superficial injury involve
a strip of the endothelial covering over the plaque
sub-endocardial connective tissue matrix is then exposed and platelet adhesion occurs because of collagen reaction
what does deep endothelial injury fissuring involve
an advanced plaque with a lipid core
the plaque cap tears (ulcerates, ruptures) allowing blood from the lumen to enter inside the plaque
the core surfaces and tissue factors from macrophages along with exposed collagen - highly thrombogenic
