Macro reentrant atrial tachycardia

**Definition:** An atrial arrhythmia in which there is intra-atrial reentry or circus movement around a fixed or functional central obstacle. The central obstacle may consist of normal (e.g. valves) or abnormal (e.g. scar) structures.

This form of SVT originates in the atrium; conduction to the ventricles is not necessary for the tachycardia to continue. An organised atrial rhythm with a rate typically between 250 and 350 bpm, including tachycardias using a variety of reentry circuits that often occupy large areas of the atrium ("macro-reentrant"). Here the arrhythmia involves the cavotricuspid isthmus.