Flashcards in MOD 6 Deck (55)
The thickening and hardening of arterial walls as a consequence of atheroma.
The accumulation of intracellular and extracellular lipids in the intima and media of medium and large sized arteries.
The thickening of the walls of arteries and arterioles usually as a result of hypertension of diabetes mellitus.
Describe the cellular events that cause chronic endothelial injury:
1. raised LDL
2. 'toxins' e.g. cigarette smoke
4. Haemodynamic stress
Describe the effects of endothelial injury on platelets, smooth muscle cells, lipid, macriphages and monocytes:
Endothelial injury causes:
1. Platelets: PDGF release
2. Smooth muscle cells: proliferation, migration and uptake of lipid
3. Lipid: insudation, LDL oxidation
4. Macrophages: uptake of lipid, migration of monocytes into intima.
What is the macroscopic morphological appearance of atheroma?
1. Fatty streak
2. Simple plaque
3. Complicated plaque (calcification, thrombosis, haemorrhage, aneurysm formation)
What is the microscopic morphological appearance of the early changes of atheroma?
1. Accumulation of foam cells
2. Proliferation of smooth muscle cells
3. Extracellular lipid deposition
What is the microscopic morphological appearance of the later changes of atheroschlerosis?
3. Cholesterol clefts
4. +/- inflammatory cells
5. Disruption of internal elastic lamina
6. Damage extends into tunica media
7. Ingrowth of blood vessels
8. Plaque fissuring
What is an aneurysm?
An excessive localised swelling of the wall of an artery.
List some clinical effects of ischaemic heart disease:
1. Sudden death
2. Myocardial infarction
3. Angina pectoris - chest pain on exertion
4. Arrythmias e.g. AF, these can be fatal
5. Cardiac failure - scarred heart, peripheral oedema and SOB
List some clinical effects of cerebral ischaemia?
1. Transient ischaemic attack (mini stroke)
2. Cerebral infarction (stroke)
3. Multi-infarct dementia
List some clinical effects of mesenteric ischaemia?
1. Ischaemic colitis - present with rectal bleeding and sometimes abdominal pain
3. Intestinal infarction - thrombus or embolus in branch of SMA
List some clinical effects of peripheral vascular disease?
1. Intermittent claudication - pain in legs due to reduced blood supply
2. Leriche syndrome - pain in buttocks - associated with impotence as a result of impaired blood supply
3. Ischaemic rest pain - muscle hurt without exercise, if left untreated -> gangrene
4. Gangrene - loss of blood supply leading to visible necrosis.
List the different hypotheses for the mechanism of atherogenesis:
Response to injury/insudation hypothese
Lipid oxidation hypothese
What cells are involved in atherogenesis?
Endothelial cells, platelets, smooth muscle cells, macrophages, lymphocytes and neutrophils.
List some risk factors for atherosclerosis:
age, gender, Smoking, hypertension, impaired glucose tolerance, hyperlipidaemia, alcohol, apoliprotein E genotype, geography, infection
What changes in lifestyle can you make to reduce the risk of atheroschlerosis?
1. Stop smoking
2. Decrease fat intake
3. Sensible alcohol intake
4. Regular exercise and control of weight
What therapeutic interventions can reduce the risk of atherosclerosis?
1. Treat hypertension e.g. beta blockers
3. Treat diabetes mellitus
4. Lipid lowering drugs where needed e.g. statins
The first sign of an atheroma is thought to be a fatty streak. What does this look like macroscopically?
Yellow and slighly raised due to lipid deposits in the intima. However its relation to atheroma is somewhat debatable - does have slightly different anatomical locations.
What does the simple plaque stage of atheromas look like macroscopically?
1. Raised yellow/white
2. Irregular outline
3. Widely distributed
4. Enlarge and coallesce
What complications can happen and thus create a complicated plaques?
2. Haemorrhage into the plaque
3. Calcification (can see on X-ray)
4. Aneurysm formation
Where are common sites for atheroma?
1. Aorta - especially abdominal
2. Coronary arteries
3. Carotid arteries
4. Cerebral arteries
5. Leg arteries
Describe the normal structure of an artery, from deep to superficial layers:
2. Sub-endothelial connective tissue
3. internal elastic lamina
4. Muscular media
5. External elastic lamina
What happens to the proportion of elastic tissue in arteries as you move further away from the heart?
Decreases - lower amplitude pressure pulses the further from the heart you go
What are the consequences of disruption of the internal elastic lamina in the later changes of atheroma?
It alters the compliance of arteries - its ability to expand and contract passively in response to pressure changes.
Why is there an ingrowth of blood vessels seen as part of the later changes of atheroma?
Due to the accumulation of lipid and proliferation of smooth muscle cells, new vessels respond by getting into the area that now requires a larger blood supply.
What are the consequences of plaque fissuring in the later changes of atheroma?
It releases material into the blood stream that promotes thrombosis.
What are the effect of age on risk of atheroma?
The risk slowly increases throughout adult life.
What are the effect of gender on risk of atheroma?
Women are relatively protected before the menopause but catch-up after. This is presumably due to a hormonal basis.