Antiarrhythmic drugs

Cardiac muscle is unique in that it has automated or pacemaker cells and non-automated (contractile) cells. Pacemaker cells are found in the sinoatrial (SA) node, atrioventricular (AV) node, and the conduction system of the heart, while contractile cells are found in the atria and ventricles. The cardiac action potential (AP) of both these cell groups differs and results from the sequential changes in membrane permeability to Na+, K+, and Ca2+ and the flow of these ions through ion channels. Understanding the physiology of cardiac conduction enables the understanding of the pathophysiology of arrhythmogenesis and the targets of antiarrhythmic drugs (AADs). The Singh Vaughan-Williams framework is the simplest classification system for AADs and is based on the main mechanism of action of each drug. It has recently been expanded to include previously unclassified AADs and broaden the mechanisms of action. The pharmacology and clinical applications of commonly used AADs are discussed.