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Know mechanism for plateau phase of action potential in cardiac cells.
- Cardiac cells have plateau phase
- - Leveling off of repolarization prolongs period of depolarization (electrical excitation)
- - Duration of action potential (AP) longer
- - Ensures all cells of ventricles excited at approximately same time so ventricular muscles contract as unit
- - If no plateau, heart is not an efficient pump
- Inward movement of Ca2+ - maintain plateau
- - Channels activated by depolarization
- - Open when potential reaches -30mV
- - Influx of Ca2+ important in initiating contraction of cardiac muscle just like skeletal muscle
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What measures would you recommend to patients in effort to lower LDL-C and increase HDL-C? (p.22)
- Decrease SFA and cholesterol in diet
- Niacin – to decrease liver synthesis of VLDL
- Exercise – to increase HDL
- Moderate alcohol intake
- Cholesterol lower drugs (Statins)
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What measures would you recommend to lower TG?
- Weight loss if overweight
- Exercise
- Decrease intake of SFAs
- Substitute MUFAs for SFAs, but do not increase total calories
- Limit CHO to 55% of calories or less
- o Consume more complex CHO like whole grains, fruits, vegetables
- o Limit simple sugars in sweets and soft drinks
- Avoid alcohol
- Fish oil supplements (omega-3)
- Niacin
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Know risk factors for heart disease and mechanisms involved. (p.21-25)
- Family history of premature coronary heart disease
- Age – male >= 45; female >=55
- Personal history of peripheral or cerebrovascular disease
- Cholesterol levels
- Hypertriglyceridemia (fasting)
- Hypertension
- Cigarette smoking
- Diabetes
- Obesity
- Metabolic syndrome
- Physical inactivity
- Diet
- Hyperhomocysteinemia
- CRP
- Lipoprotein a
- Chronic infection
- Type A behavior
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Know specific values recommended for LDL-C, HDL-C, Total cholesterol, TG, Fasting plasma glucose:
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Review JNC hypertension guidelines and know most recent AHA recommendations. (p.22-23)
- Hypertension = BP > 140-90 mmHg
- Normal = 120/80 mmHg
- Pre-hypertension = 120-139 / 80-89
- Stage 1 HTN = 140-159 / 90-99
- Stage 2 HTN = SBP > 160; DBP > 100
- Treatment goal for HTN patients:
- o Target < 140/90
- o With renal disease or diabetes < 130/80
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Review pathophysiology of atherosclerotic process – from soft lipid “unstable” atheromatous plaque to fibrous plaque to complicated advanced calcified plaque. (p.26-28)
- Initiating step – development of “fatty streak” – atheromatous soft-lipid plaque
- Followed by formation of fibrous plaque
- Ultimately an advanced-complicated lesion
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What stage of plaque development most likely (vulnerable) to rupture and thrombus? (p.27)
- Smaller ones
- Activated foam cells (fat-filled macrophages) at margins of small lipid plaques secrete enzymes that disrupt integrity of thin fibrous cap, making plaque vulnerable to rupture
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