The best answer is D: All of the above.
Here's Why: Lidocaine (class 1B) is a pure sodium channel blocker that has been shown to be effective in treating ischemic ventricular arrhythmias. Procainamide (class 1A), in ventricular muscle and Purkinje fibers, suppresses phase 4 diastolic depolarization, hence reduces the automaticity of all pacemakers. It also slows intra-ventricular conduction, suppressing re-entry arrhythmias. If there is ischemic tissue and conduction is already slowed, procainamide may further slow conduction and produce bi-directional block and may terminate re-entry arrhythmias. Amiodarone (class III) is effective in both supraventricular and ventricular arrhythmias, however, it takes protracted periods of time to obtain therapeutic blood levels; has a very long half-life; and, has a long list of serious potential side-effects. Many practitioners believe that its use should be a bridge to definitive therapy such as radio-frequency ablation.
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