Vaughan Williams classification


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Vaughan Williams classification

Cardiology 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