Atheroma Flashcards
What is the process of atheroma?
Atherosclerosis
What is atheroma?
The formation of focal elevated lesions (plaques) in intima of large and medium sized arteries
Give an example of somewhere that plaques may form that has clinical implications
Coronary arteries - atheromatous plaques narrow lumen - ischaemia of the myocardium (clinical manifestation is angina)
What is meant by a complicated plaque?
When the plaque ruptures (atheromatous plaque - lipid-rich core and fibrous cap)
What causes 90% of MI’s?
Rupture of a plaque in the coronary artery - thrombus/blood clot forms on top therefore occluding the lumen (blocking blood supply to the myocardium)
What effect does blocking the blood flow to the myocardium have?
Ischaemia -> infarction
What is stable angina?
Predictable chest pain that comes on in exertion
What causes the pain felt in stable angina?
Increased oxygen demand of the myocardium
What is unstable angina?
Unpredictable chest pain that comes on at rest
What causes the pain felt in unstable angina?
Decreased oxygen supply by the coronary arteries
What is a thromboembolism?
Obstruction of a blood vessel by a blood clot that has become dislodged from another site in the circulation
What colour is plaques in the intima?
Yellow
What is arteriosclerosis?
Not atheromatous plaques - age related changes in muscular arteries (thickening and hardening of the walls of the arteries), decreasing vessel diameter
What should the diameter of the intima be?
Thin
What is a fatty streak?
Earliest significant lesion in young children - yellow linear elevation of intimal lining due to masses of lipid-laden macrophages (no clinical significance and may disappear, however, patients at risk can go onto form atheromatous plaques)
What is the next stage?
Early atheromatous plaque - young adults onwards, smooth yellow patches in intima due to lipid laden macrophages (progress to established plaques)
What is a fully developed atheromatous plaque?
Central lipid core with fibrous cap, covered by arterial endothelium
What holds the structure of the plaque?
Collagens (produced by smooth muscle cells - in tunica media) in cap provide structural strength
What are foamy macrophages?
Macrophages that appear foamy due to their uptake of oxidised lipoproteins
What is the lipid core made up of?
Rich in lipids and debris derided from macrophages
What occurs late in plaque development and is often a marker on angiograms/CT?
Calcification
What is the most important risk factor for atheroma?
Hypercholesterolaemia
What is bad cholesterol?
LDL
How many Caucasians are heterozygous for a mutation that causes a genetically determined lack of cell membrane receptors for LDL?
1/500
How many patients in the UK are homozygous for this mutation?
1 in 1 million - usually die from coronary artery disease in teens - the defect makes the body unable to remove LDL (bad) cholesterol from the blood - this results in a high level of LDL in the blood
What are some signs of major hyperlipidaemia?
Familial Biochemical evidence Corneal arcus Tendon xanthomata Xanthelasmata
What are the other risk factors for atheroma?
Smoking (damages vessel walls) Hypertension (damages vessel walls) Diabetes (damages vessel walls) Male Elderly
What are some less strong risk factors for atheroma?
Obesity
Sedentary lifestyle
Low socio-economic status
Low birthweight
What is the two step process that causes the development of atheromatous plaques?
Injury to endothelial lining of artery
LDL passes through endothelium of blood vessel and lodges in the intima
What are patients given who have high cholesterol?
Statins - lower LDL cholesterol and increase HDL cholesterol
What is the difference in vessel lumen between stable angina and unstable angina?
Stable angina is stenosed coronary artery
Unstable angina is very stenosed coronary artery - they don’t need to exert themselves for the lack of oxygen and blood flow to be noticeable
What is ischemic pain of myocardium called?
Angina
What happens when an artery in the legs gets stenosed?
Intermittent clauducation - clinical manifestation of peripheral arterial disease (muscles in the legs don’t get enough blood and therefore oxygen when you exercise - pain stops when you stop walking)
What does total occlusion of the coronary artery, carotid artery and the popliteal artery cause?
Myocardial infarct
Cerebral infarct
Lower limb gangrene (infarct)
What can embolic occlusion of small vessels cause?
Small infarcts in organs
What can happen with a thrombus in artery?
Small thrombus fragments can detach and embolise
What can a plaque cause (not including if it ruptures)
Can cause the media below to become weak and therefore cause an aortic aneurysm (often asymptomatic and sudden rupture has a high mortality)
What plaques have a high risk of rupture?
Typically thin fibrous cap, large lipid core and prominent inflammation
What are ways to help prevent atheroma?
Stop smoking Control blood pressure Weight loss Regular exercise Dietary modifications Cholesterol lowering drugs
(aspirin - inhibits platelet aggregation to decrease the risk of thrombus forming on established plaques)
What is vascular disease?
Atherosclerosis in all different places - can cause heart attacks, strokes and peripheral vascular disease
