MOD S7 - Atheroma Flashcards
Define atherosclerosis
The thickening and hardening of arterial walls as a result of atheroma
Define atheroma
The accumulation of intracellular and extracellular lipid in the tunica intima and tunica media of large and medium sized arteries
Define arteriosclerosis
The thickening and hardening of arterial and arteriolar walls, usually as a result of diabetes mellitus or hypertension
Describe the macroscopic appearance of an early atheroma
Fatty streak
Lipid deposits in the tunica intima
Yellow and slightly raised
Describe the macroscopic appearance of a developing atheroma
Simple plaque Raised yellow/white Irregular outline Widely distributed Enlarged and coalesced
Describe the microscopic appearance of a developing atheroma
Microscopic:
Proliferation of smooth muscle cells
Accumulation of foam cells
Extracellular lipid
Describe the microscopic appearance of a late-stage atheroma
Fibrosis Necrosis Cholesterol clefts Cholesterol deposition in tissues (not plaque) Inflammatory cells
Describe the macroscopic appearance of a late-stage atheroma
Later: Complicated plaque Thrombosis Haemorrhage into plaque Calcification Aneurism formation
Describe the cellular events that take place in atheroma formation
Endothelial damage occurs
Platelets arrive
PDGF released (platelet derived growth factor)
Smooth muscle cells proliferate
Smooth muscle cells migrate and take lipid with them
Macrophages arrive and phagocytose the lipid, becoming foam cells
What could some effects of atherosclerosis be if it was in a coronary artery?
Ischaemic heart disease Angina Arrhythmias Cardiac failure MI Sudden death
What could some effects of atherosclerosis be if it was in the brain?
Transient ischaemic attack (symptoms for <24h)
Cerebral infarction (aka stroke)
Multi infarct dementia
What could some effects of atherosclerosis be if it was in a mesenteric artery?
Ischaemic colitis
Malabsorption
Intestinal infarction
Aneurism formation due to high pressure, hardening and weakening
What could some effects of atherosclerosis be if it was in a peripheral artery?
Peripheral vascular disease Intermittent claudication Leriche syndrome Ischaemic rest pain Gangrene
What is intermittent claudication?
Pain on exertion of calf muscles
Due to blockage or narrowing of peripheral arteries causing pain and ischaemia
NB intermittent claudication in the iliac artery causes gluteal pain
What are some risk factors for atheroma?
Age Gender Hyperlipidaemia Smoking Hypertension Diabetes mellitus Alcohol Infection Lack of exercise Obesity Stress Oral contraceptives
Why is gender a risk factor for atheroma?
Pre-menopausal women have some measure of resistance to atheroma
Thought to be hormone related
NB slightly conflicts with oral contraceptives
Briefly describe the unifying hypothesis of atherogenesis
Endothelial injury occurs
Platelets adhere to vessel walls
PDGF secreted
Smooth muscle cell proliferation and migration
Insudation of lipid
Uptake of lipid by SMCs and macrophages
Migration of monocytes into tunica intima
Foam cells secrete cytokines
Cytokines further stimulate SMCs and recruit immune cells
How may atheromas be prevented?
Stop smoking Change diet (less fat) Change lifestyle (more exercise) Treat hypertension Treat diabetes Lipid-reducing drugs
What can increase susceptibility to CHD?
Genetics eg familial hypercholesterolaemia
Geographical location (less common in Mediterraneans)
Ethnicity (Asians are more prone to CHD)
