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# Vaughan Williams Classification **1a.** **Sodium Channel Blockade:** * **Reduced number of $Na^+$ channels:** Repolarization and action potentials last longer, leading to supraventricular and ventricular arrhythmias. * **Examples:** Disopyramide, procainamide, quinidine * **Sodium chann...

# Vaughan Williams Classification **1a.** **Sodium Channel Blockade:** * **Reduced number of $Na^+$ channels:** Repolarization and action potentials last longer, leading to supraventricular and ventricular arrhythmias. * **Examples:** Disopyramide, procainamide, quinidine * **Sodium channel blockade in abnormal heart tissue:** Ventricular arrhythmias. * **Example:** Lidocaine, mexiletine * **Reduced number of $Na^+$ channels and inward $Ca^{2+}$ channels:** Minimal effect on repolarization. Atrioventricular and ventricular arrhythmias. * **Example:** Flecainide, propafenone **2.** **β-adrenergic receptor antagonist (β-blocker):** * AV blockades * Reduces spontaneous depolarization and conduction. * Atrial and ventricular arrhythmias. * **Examples:** Atenolol, bisoprolol, metoprolol, propranolol, esmolol **3.** **Potassium Channel Blockade:** * Prolongs action potential duration. * Supraventricular and ventricular arrhythmias. * **Examples:** Amiodarone, sotalol **4.** **L-type Calcium Channel Blockade:** * Slows conduction velocity. * Reduced heart rate and contractility. * Supraventricular arrhythmias. * **Examples:** Verapamil, diltiazem **Rhythm Control:** amiodarone, flecainide, sotalol **Rate Control:** metoprolol, verapamil, digoxin