Nitrates and Calcium Channel Blockers Flashcards by A B

Stable Angina

fixed, stable obstruction

myocardial ischemia induced by increased exercise

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Define variant or prinzmetal angina

vasospasm of coronary arteries

sx at rest not exercise

transient ST elev

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Define unstable angina

increased freq, duration, intensity of angina with less exertion or at rest

high chance of MI

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Regulating myocardial O2 supply

metabolic regul

1) metab stress
2) decr ATP syntheiis –> produce adenosine
3) adenosine vasodilate and incr coronary flow

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Regulating myocardial O2 supply

humoral factors

incr risk of thrombus +/- vasospasm

Ach, angiotensin, bradykinin, NO

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Regulating myocardial O2 supply

mechanical factors

coronary arteries perfused during diastole –> duration (HR) regulates

incr preload or LVEDP, incr ventricle pressure, decr perfusion

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factors that affect myocardial O2 demand

1) HR
2) wall tension
3) inotropic state

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what do nitrates do?

relax smooth muscle

vasodilator

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mechanism of nitrates

NO donors

1) NO stim guanylyl cyclase
2) incr cGMP
3) activ PKG
4) decr cyto Ca2+ –> relaxation and vasodilation

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what does vasodilation do?

1) decr preload (incr perfusion)
2) decr afterload
3) dilation of epicardial vessels

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where is vasodilation most effective?

venous side

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how can your myocardial cells be tolerant to nitrates

depletion of -SH required for NO formation

–> thus dose eccentrically

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what is the secondary effect of nitrates

antithrombotic

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when do you use nitroglycerin

acute angina

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time of action for nitroglycerin

30sec -5 min

lasts 30 min

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side effects of nitroglycerin

1) HA
2) hypotension
3) reflex tachycardia
4) paradoxical bradycardia

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describe isosorbide dinitrate

sublingual and orally available

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describe isosorbide-5-mononitrate

once a day dosing (prevent tolerance)

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mechanism of beta blockers

binds to b1 receptors in heart and b2 receptors in smooth muscle

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effect of beta blockers on heart

1) decr HR
2) decr contractility
3) incr diastolic filling, incr perfusion
4) decr wall stress, decr O2 demand

what are cardioselective beta blockers

preferentially target b1 b/c targeting b2 causes decr vasodilation and bronchodilation

describe type of beta blocker

propanolol

targets b1 and b2

no intrinsic SA activity

effect of propanolol

1) decr contractility
2) decr resting and exercising HR
3) decr resting BP
4) anti-arrhythmic (decr AV conduction)

when is propanolol contraindicated

pts with LV dysfunction

side effects of propanolol

1) bradycardia 2) AV block 3) decr LV function 4) bronchoconstriction 5) fatigue 6) intensify insulin-induced hypoglycemia

describe type of beta blocker metoprolol

highly b1 selective | no intrinsic SA

effect of metoprolol

1) used in mild to mod CHF 2) decr resting and exercise HR 3) decr contractility 4) decr resting BP 5) decr AV conduction 6) anti-arrhythmic

describe type of beta blocker labetalol

nonselective B blocker + a1 blocking ability slightly ISA

effect of labetalol

1) decr contractility 2) decr resting BP 3) decr AV conduction 4) anti-arrhythmic 5) vasodilatory

caution giving beta blockers in which patients

some pts with CAD also have CHF and on digoxin (also AV blocker)

effect of calcium channel blockers

block L-type Ca2+ channels

symptom effect of calcium channel blockers

1) decr HR 2) decr contractility 3) decr peripheral vascular resistance and BP

where is calcium channel blockers most effective

arterial side

what is nifedipine

dihydropyridine Ca2+ channel blocker

describe dihydropyridines 1st gen nifedipine

1) vasodilators 2) decr contractility 3) decr AV node conduction 4) decr HR

side effects of dihydropyridines 1st gen nifedipine

1) hypotension --> reflex tachycardia | 2) contraindicated for LV dysfunction

what are the 2nd gen dihydropyridines

nicardipine amlopidipine

what differs btwn 2nd gen and 1st gen dihydropyridines

2nd gen "vascular selective" - less inotropic - less chronotropic

effect of amlodipine

long duration of action vasodilation minimal inotropic effect

where do you use amlodipine

LV dysfunction

Describe verapamil effect

1) vasodilators 2) decr HR 3) decr contractility

when is verapamil contraindicated

LV dysfunction | Nodal disease

effects of diltiazem

intermediate btwn nifedipine and verapamil

what do you use to treat stable angina

1) treat lipid, HTN, anti-platelet 2) sublingual nitro 3) aspirin 4) beta blocker or calcium channel blocker 5) long acting nitrate 6) revasc with

when do you use beta blockers for stable angina

when ischemia due to primary incr O2 demand with fixed supply

when do you use calcium channel blockers for stable angina

when decr O2 supply caused by alterations to coronary vasomotor tone

what do you use to treat variant angina

1) Ca2+ channel blockers | 2) nitrates

what do you avoid in variant angina

1) aspirin 2) beta blockers because exacerbate vasospasm

what do you use to treat unstable angina

1) hospitalization 2) IV nitro 3) beta blocker 4) antiplatelet (aspirin) 5) anticoag (aspirin, heparin or both)