Atherosclerosis: Risk Factors
Terms
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- Atherosclerosis
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slowly progressive disease
ARTERIES: elevated fibro-fatty intimal plaques
INTIMAL PLAQUES
lipid deposition
SMC proliferation
ECM synthesis - Constitutional risk factors
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AGE: risk INC. with advancing age
SEX: F protected before menopause
Familial disposition - Controllable major risk factors
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Hyperlipidemia
HT
Smoking
DM
Note: it follows that the risks can be reduced by measures that manage or prevent the ‘controllable’ risk factors. - Other minor risk factors
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Obesity (>30% overweight)
Sedentary lifestyle with low physical activity
Stress or type A personality behaviour (aggressive competitive)
HI homocystine levels = HI lipoprotein
HI CHO diet: hardened unsaturated fat intake
POST MENO oestrogen deficiency - Hyperlipidemia
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lipids in atheromatous plaques consist mainly of cholesterol;
DEC. cholesterol (by drugs) = DEC atheroma and the risks of compx -
Hyperlipidemia
how do chol. levels + risk correlate? -
Risk ~ level of serum low-density lipoprotein (LDL), formed from the catabolism VLDL
LDL carries 70% of total serum cholesterol thus high levels of which are important risk factors
Total cholesterol: >6.2mmol/L (normal <5.2)
LDL cholesterol: > 4.2mmol/L (normal <3.4)
Elevated LDL levels =accelerated atherosclerosis. -
Hyperlipidemia and hypercholesterolemia
Causes? -
Familial abnormalities (of LDL receptor gene or in various apolipoprotein genes)
Diet high in CHO + SAT FAT
DM: major risk factor in itself
Hypothyroid
Others : uraemia, nephrotic syndrome, obs. liver d. - Role of HDL?
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Ris = inversely related to the level of HDL
HDL involved in reverse transport of cholesterol from cells; potentially helps clear cholesterol from vessel wall lesions = protective effect.
HDL levels
INC. by EXERCISE + moderate ALOCHOL intake
DEC. by SMOKING + OBESITY - Hypertension
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MAJOR esp. >40
BP>160/95 = x5 incidence of IHD compared to BP<140/90 - Diabetes mellitus
- INC. risk of developing MI 2 (hypercholesterolemia)
- Smoking
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>1 pack a day for years will INC. death rate from IHD by x2
i.e. STOP smoking will DEC. risk - Multiple risk factors?
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Multiple risk factors have additive effects!
2 major risk factors INC. risk of IHD by x4
3 major risk factors INC. risk of IHD by x7