19. Pathophysiology of Atheroma Flashcards
Define atheroma (atherosclerosis)
formation of focal elevated lesions (plaques) in intima of large and medium sized vessels (hardening of arteries)
What are atheromas complicated by particularly?
thromboemolism (travelling clot is called embolus which lodges in other lumens)
Define embolus.
Blood clot which TRAVELS in the body into passages that it cannot pass and can cause embolism. Often it’s a blood clot that breaks off (thromboembolus)
Define thrombus.
When a blood clot forms in the VESSEL and impedes blood flow
What do atheromatous plaques cause eventually?
- plaques narrow lumen
- lead to ischaemia (in serious consequences angina can be as a result of myocardial ischaemia)
Define ischaemia.
inadequate blood supply to tissues or organs/ part of body
Define atherosclerosis.
- build up of fatty materials inside vessels (atheromatous plaques)
- biggest causes of MIs and strokes
- proliferation of intimal smooth-muscle cells creating atheromatous plaques
Define arteriosclerosis.
- thickening and hardening of artery walls usually due to age
- age-related change in muscular arteries
What pathological process occur in arteriosclerosis? (3)
- smooth muscle hypertrophy
- apparent reduplication of internal elastic laminae
- internal fibrosis which decreases vessel diameter
What occurs to vessel diameter in arteriosclerosis and atherosclerosis?
it decreases (gets smaller)
What does arteriosclerosis mainly contribute to in elderly people? (4)
High frequency of…
- cardiac ischaemia
- cerebral ischaemia
- colonic ischaemia
- renal ischaemia
When are clinical effects more apparent in arteriosclerosis? (4)
When CV system is further stressed by :
- haemorrhage
- major surgery
- infection
- shock
What are 3 layers which make up the artery wall?(from top to bottom)
- tunica adventitia/externa
- tunica media
- tunica intima
What is the earliest stage of atheroma formation?
fatty streak (earliest significant lesion)
When does fatty streak in arteries usually appear? (earliest stage of atheroma)
in young children
Describe the fatty streak. What is it? (2)
- yellow linear elevation of intimal lining
- comprises masses of lipid-laden macrophages
What is the clinical significance of a fatty streak? (2)
- no clinical significance
- may disappear with time
What are patients with a fatty streak at risk of?
at risk of atheromatous plaques
What are the 3 stages of atheroma development?
- fatty streak
- early atheromatous plaque
- fully developed atheromatous plaque
What is the 2nd stage of atheroma formation?
early atheromatous plaque
When does early atheromatous plaque develop?
in young adults onwards
Describe the early atheromatous plaque. What is it? (3)
- smooth yellow patches in intima
- lipid-laden macrophages
- progresses to establish plaques
What is the 3rd stage of atheroma formation?
fully developed atheromatous plaque
Describe the appearance of a fully developed atheromatous plaque.
Central lipid core with fibrous tissue cap covered by arterial endothelium
What are fibres found in fibrous tissue cap of atheroma?
collagens (produced by smooth muscle cells) in cap provide structural strength
What cells are found in fibrous tissue cap of atheroma?
inflammatory cells (macrophages, t-lymphocytes,mast cells) reside in fibrous cap which release debris and waste
Where are inflammatory cells in fibrous tissue cap produced from?
recruited from arterial endothelium
Where are collagens in fibrous tissue cap produced from?
produced by smooth muscle cells
What appearance does atheroma give histologically?Why is this?
gives a foamy-like appearance due to presence of collagens and inflammatory cells in the fibrous tissue cap
What is central lipid core in atheroma rich in/ full of?
rich in cellular lipids and debris which are derived from macrophages (died in plaque)
What is the main property of atheromas which contributes to CV disease?
they are thrombogenic; often rim of foamy macrophages (cause thrombus; blood clots in situ of vessels)
Why are macrophaes regarded as “foamy”?
foamy due to uptake of oxidised lipoproteins via specialised membrane bound scavenger receptor
What other substances are often found deposited on atheromas except from fatty material?
- cholesterol crystals
- calcified material
What occurs LATE in plaque development?
dystrophic calcification is extensive in late stage
How can extensive dystrophic calcification be used diagnostically?
it can be used as a marker for atherosclerosis in angiograms and CT scans