Nitrates and Calcium Channel Blockers Flashcards
Stable Angina
fixed, stable obstruction
myocardial ischemia induced by increased exercise
Define variant or prinzmetal angina
vasospasm of coronary arteries
sx at rest not exercise
transient ST elev
Define unstable angina
increased freq, duration, intensity of angina with less exertion or at rest
high chance of MI
Regulating myocardial O2 supply
metabolic regul
1) metab stress
2) decr ATP syntheiis –> produce adenosine
3) adenosine vasodilate and incr coronary flow
Regulating myocardial O2 supply
humoral factors
incr risk of thrombus +/- vasospasm
Ach, angiotensin, bradykinin, NO
Regulating myocardial O2 supply
mechanical factors
coronary arteries perfused during diastole –> duration (HR) regulates
incr preload or LVEDP, incr ventricle pressure, decr perfusion
factors that affect myocardial O2 demand
1) HR
2) wall tension
3) inotropic state
what do nitrates do?
relax smooth muscle
vasodilator
mechanism of nitrates
NO donors
1) NO stim guanylyl cyclase
2) incr cGMP
3) activ PKG
4) decr cyto Ca2+ –> relaxation and vasodilation
what does vasodilation do?
1) decr preload (incr perfusion)
2) decr afterload
3) dilation of epicardial vessels
where is vasodilation most effective?
venous side
how can your myocardial cells be tolerant to nitrates
depletion of -SH required for NO formation
–> thus dose eccentrically
what is the secondary effect of nitrates
antithrombotic
when do you use nitroglycerin
acute angina
time of action for nitroglycerin
30sec -5 min
lasts 30 min
side effects of nitroglycerin
1) HA
2) hypotension
3) reflex tachycardia
4) paradoxical bradycardia
describe isosorbide dinitrate
sublingual and orally available
describe isosorbide-5-mononitrate
once a day dosing (prevent tolerance)
mechanism of beta blockers
binds to b1 receptors in heart and b2 receptors in smooth muscle
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)
