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23 Cards in this Set
- Front
- Back
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Class I agents
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Na channel blockers
Procainamide |
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procainamide: what does it do to threshold, conduction velocity and action potential?
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prolongs threshold, decreases conduction vel, prolongs action potential
blocks OPEN Na+ channels |
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class II agents
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beta blockers
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important SE of beta blocker
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torsades de pointes
contraindicated in wolf-white-parkinson syndrom |
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class III agents, what do they do?
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block outward K channels
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an important class III agent?
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amiodarone
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what does amiodarone do to refractoriness, AV conduction, and HR?
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prolongs refract, increases AV conduction and bradycardia
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what is special about amiodarone?
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inhibits Na+, K+ and Ca++ channels, is an alpha & beta receptor blocker (significant effects of classes other than III)
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class IV agents: the important ones
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Ca++ channel blockers, Verapamil and diltizem
FOUR VERY CLASSY DILDOS |
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adenosine
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binds to P1 purigenic receptors, opens G-protein K+ channels
used to terminate supraventricular arrythmias |
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magnesium sulfate
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treat digoxin related arrythmias, induce torrsades de pointes
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which type of channel is the principal VGCC in cardiac muscle?
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L-type, aka "slow channel"
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which are dihydropyridines?
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nifedipine, amlodipine
(KATIE and her friend AMY) |
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which are non-dihydropyridines?
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diltiazem and verapamil (also class IV agents)
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calcium channel blockers and pre-load, explain
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all Ca++ channel blockers reduce arteriolar resistance, but none have significant effects on most venous beds, so they have no effect on preload
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what do the dihydropyridines do to Ca++ channels?
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slow the inward current of Ca++, no effect on recovery rate
minimal effects on sinus node automatism and AV conduction |
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how do the non-hydropy effect the heart?
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they recuce BOTH Ca++ influx and rate of recovery, have big effects on sinus node automatism and AV conduction......
reduce heart rate and velocity (used in superventricular tachyarrhthmias DON'T COMBINE WITH BETA BLOCKERS |
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when are Ca++ channel blockers contracindicated?
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pts with cardiac block, systolic dysfunction or Beta Blocker Tx
(DON'T BLOCK CA++ CHANNELS IF ALREADY BLOCKING SOMETHING ELSE) |
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What are most DDIs related to with Ca++ channel blockers?
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metabolism.... they are hepatically metabolized (first pass)... can still be administered orally
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what is a major difference between non-dihyro and dihydropyrimidines?
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non-di are more cardiac selective and less vasoactive... they are therefore used for Tx for cardiac problems, rather than anti-hypertensive
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what does the PR interval represent?
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AV conduction time (time between atrial and ventricular depolarizations)
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what does the ST segement represent?
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plateau of ventricular action potential
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what does QT period represent?
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time from ventricular depolar --> repolar
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