Overview of Basic Mechanisms of Cardiac Arrhythmia

A cardiac arrhythmia simply defined is a variation from the normal heart rate and/or rhythm that is not physiologically justified. Recent years have witnessed important advances in our understanding of the electrophysiologic mechanisms underlying the development of a variety of cardiac arrhythmias. The mechanisms responsible for cardiac arrhythmias are generally divided into 2 major categories: (1) enhanced or abnormal impulse formation (ie, focal activity) and (2) conduction disturbances (ie, reentry) (Fig. 1). Fig. 1 Classification of active cardiac arrhythmias.