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Study Area - Medications

  Class I: Bind to sodium channel, decrease speed of depolarization.
  Class Ia: Slow Upstroke of action potential, prolong duration of action potential, decrease conductivity, increases refractoriness.
Quinidine, Procainamide, Disopyramide
    Class Ib: Minimal effect on upstroke of action potential, shorten duration of action potential, decreases refractoriness.
Lidocaine, Phenytoin, Tocainide, Mexiletine
    Class Ic: Marked slowing of upstroke of action potential, minimal effect on action  potential duration, marked decrease in conductivity, little effect on refractoriness.
Flecanide, Encainide, Propafenone

Class II:


Beta blocking drugs, decrease sympathetic tone, affects mainly SA and AV nodes, affect  is indirect by blocking beta receptors.
Atenolol, Labetolol, Metropolol, Nadolol, Propranolol, Timolol

  Class III: Increase action potential duration.
Amiodarone, Bretylium, Sotalol, Procainamide
  Class IV: Calcium channel blockers, affects mainly SA and AV nodes, affect is direct because SA and AV node depolarization is controlled by slow calcium channels.
Diltiazem, Verapamil
  Class V: Digitalis Agents, increased parasympathetic activity
Digoxin, Digitalis
Source; Richard Fogoros, Electrophysiology Testing
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