Session 6 Flashcards
What is an atheroma?
The accumulation of intracellular and exit acellular lipid in the intima and media of large and medium sized arteries.
What is atherosclerosis?
The thickening and hardening of arterial walls as a consequence of atheroma.
What is arteriosclerosis?
The thickening of the walls of arteries and arterioles as a result of hypertension or diabetes mellitus.
What are the macroscopic characteristics of an atheroma?
A yellow and slightly raised fatty streak.
Simple plaque - irregular outline.
Complicated plaque - thrombosis, haemorrhage, calcification.
What are the common sites of an atheroma?
Aorta, especially abdominal. Coronary Carotid Cerebral Leg arteries
What are the early microscopic characteristics of an atheroma?
Proliferation of smooth muscle cells.
Accumulation of foam cells.
Extra cellular lipid.
What are the later microscopic characteristics of an atheroma?
Fibrosis. Necrosis. Cholesterol clefts - occur as organic solvent destroys the cholesterol. Disruption of internal elastic lamina. Damage extends into media. In growth of blood vessels. Plaque fissuring.
What are some of the effects of an atheroma?
Ischaemic heart disease. Sudden death. Myocardial infarction. Angina pectoris. Arrhythmias. Cardiac failure.
What other types of ischaemia are there?
Cerebral (and transient ischaemic attack) Mesenteric ischaemia (malabsorption, infarction)
What are some of the consequences of peripheral vascular disease?
Intermittent claudication - pain on walking.
Leriche syndrome - aortiliac occlusive disease.
Ischaemic rest pain - pain on rest after walking.
Gangrene - necrosis due to loss of blood supply.
How does age effect the risk of atheroma?
As the patient gets older, the chances of atheroma slowly increase?
How does gender effect the risk of atheroma?
Women are protected more before menopause.
How does hyperlipidaemia effect the risk of atheroma?
There is high plasma cholesterol which increases the risk.
How does smoking effect the risk of atheroma?
Smoking increases the risk, then this risk radially falls after quitting smoking.
How does hypertension effect the risk of atheroma?
The mechanism is uncertain, but it does increase the risk. Possibly due to the high pressures damaging endothelium.
How does diabetes mellitus effect the risk of atheroma?
Increases the risk by about double. This makes pre menopausal women loose their protective effect.
How does alcohol effect the risk of atheroma?
More than 5 units a day increases the risk. Small amounts may be protective.
How does infection effect the risk of atheroma?
It is thought that it can increase the risk. Examples would be chlaymidia pneumoniae, helicobacter pylori.
How does genetics effect the risk of atheroma?
It may increase the risk if there is a mutation I’m the apolipoprotein metabolism or receptors.
What other lifestyle choices increase the risk of atheroma?
Obesity No exercise Soft water Oral contraceptives Stress Personality
What are the 4 theories for the causes of atheroma?
Thrombogenic theory
Insudation theory
Monoclonal hypothesis
Reaction to injury hypothesis
What does the insudation theory state?
That endothelial injury causes inflammation and an increased permeability to lipids from the plasma.
What does the monoclonal hypothesis state?
The the crucial role in atheroma formation is the proliferation of smooth muscle. Each plaque is monoclonal and starts from one cells. Abnormal growth occurs. (In a similar way to tumour formation)
What does the reaction to injury hypothesis state?
There is endothelial injury, this causes a plaque to form. Platelet adhesion occurs and PDGF is released (causing more smooth muscle proliferation) Monocytes penetrate the endothelium and smooth muscle cells proliferate more.
LDL is especially bad, when oxidised, for endothelium.
