A detailed hierarchal nomenclature of arrhythmias is offered with definition of 
its applications to diagnosis and complications. The conceptual and 
organizational approach to discussion of arrhythmias employs the following 
sequence: location--mechanism--aetiology--duration. The classification of 
arrhythmias is heuristically divided into an anatomical hierarchy: atrial, 
junctional, ventricular, or atrioventricular. Mechanisms are most simplistically 
classified as either reentrant, such as macro-reentrant atrial tachycardia, 
previously described as atrial flutter, or focal, such as automatic or 
micro-reentrant tachycardia, for example, junctional ectopic tachycardia. The 
aetiology of arrhythmias can be either iatrogenic, such as postsurgical, or 
non-iatrogenic, such as genetic or congenital, and in many cases is 
multi-factorial. Assigning an aetiology to an arrhythmia is distinct from 
understanding the mechanism of the arrhythmia, yet assignment of a possible 
aetiology of an arrhythmia may have important therapeutic implications in 
certain clinical settings. For example, postoperative atrial arrhythmias in 
patients after cardiac transplantation may be harbingers of rejection or 
consequent to remediable imbalances of electrolytes. The duration, frequency of, 
and time to occurrence of arrhythmia are temporal measures that further refine 
arrhythmia definition, and may offer insight into ascription of aetiology. 
Finally, arrhythmias do not occur in a void, but interact with other organ 
systems. Arrhythmias not only can result from perturbations of other organ 
systems, such as renal failure, but can produce dysfunction in other organ 
systems due to haemodynamic compromise or embolic phenomena.