Antiarrhythmic drugs: electrophysiological basis of their clinical usage.

Cardiac arrhythmias arise from abnormalities of impulse initiation or impulse conduction or both. A review of the electrophysiological mechanisms of the genesis of cardiac arrhythmias and of the electrophysiological principles of the treatment of the cardiac arrhythmias leads to: categorization of antiarrhythmic drugs into five classes based on their dominant cardiac electrophysiological actions; a series of categories of their effects on impulse initiation and impulse conduction in different types of cardiac cells; and a systematic approach to pharmacological management of cardiac arrhythmias.