Vaughan Williams classification

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