Implications of Antiarrhythmic Pharmacology

Antiarrhythmic pharmacology is often categorized according to the Vaughan Williams classification system. This system classifies 4 groups of medications according to their mechanism of action, with 3 of the 4 groups impacting the cardiac action potential. The fourth group in this classification system exerts its antiarrhythmic effect by blocking the β₁-adrenergic receptors of the sympathetic nervous system. One limitation of this classification system is that most medications impacting the cardiac action potential affect more than 1 ion channel. Although calcium channel blockers impact the slow calcium channel of the cardiac action potential, they are considered safer medications than those that block the fast sodium channel and the potassium channel.¹ 

This column focuses on the cardiovascular and electrophysiological effects of sodium and potassium channel blockers and other important clinical considerations in the care of patients receiving these class I and class III agents. If a medication is temporarily...