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Vaughan Williams classificationCardiology The system by EM Vaughan Williams, used to categorize effects of antiarrhythmics by class. See Antiarrhythmic drugs. Cf Sicilian Gambit.
Vaughan Williams Classification of Antiarrhythmic Drugs
Class I Sodium-channel blockers
IA Moderately slow conduction, moderately prolonged duration of action potential–active in atria, ventricles; most cardiotoxic group
Examples Quinidine, procainamide, diisopyramide
IB Minimally slowed conduction, shortened duration of action potential–active in atria; greatest potential for proarrhythmias
Examples Lidocaine, mexiletine, tocainamide, phenytoin
IC Markedly slowed conduction, minimally duration of action potential–active in atria, ventricles; most effective group
Examples Flecainide, encainide, propafenone, moricizine
Class II Beta blockers–active in AV nodes, ventricles; virtually no proarrhythmic effect
Class III Potassium-channel blockers; prolonged duration of action potential
Examples Amiodarone, bretylium, sotalol, ibutilide
Class IV Calcium-channel blockers–active in AV nodes; virtually no proarrhythmic effect
Abbreviation for intraarterial;
Abbreviation for intraarterial.