Vaughan-Williams — Antiarrhythmic drug classes
Classifying antiarrhythmics for board-style recall + interaction prediction
Mnemonic device
Class I-IV
Mapping
I — Sodium channel blockers
Ia (quinidine, procainamide, disopyramide) — ↑ QT; Ib (lidocaine, mexiletine) — ↓ QT, V-tach; Ic (flecainide, propafenone) — ↑ QRS, contraindicated post-MI
II — Beta-blockers
Esmolol, metoprolol, propranolol, atenolol — slow AV nodal conduction; treat SVT, atrial fib rate control
III — Potassium channel blockers
Amiodarone, sotalol, ibutilide, dofetilide — prolong action potential + QT; treat VF/VT, atrial fib
IV — Calcium channel blockers
Diltiazem, verapamil — slow AV nodal conduction; rate control in atrial fib/flutter; AVOID with WPW
Other
Adenosine (transient AV block — SVT diagnosis + treatment); digoxin (vagal + Na/K-ATPase); magnesium (torsades)
Clinical note: Amiodarone is technically class III but has properties of all 4 classes. WPW + AV-nodal blockers (CCBs, beta-blockers, digoxin, adenosine) → preferential conduction down accessory pathway → VF risk. Use procainamide or DC cardioversion instead.