Atrial tachycardia is a common atrial arrhythmia seen in individuals who have valvular disease or other structural heart disease; it is sometimes seen in people who have a structurally normal myocardium as well. Less common than atrial fibrillation and AV node reentrant tachycardia, it is probably more common than AV-reciprocating tachycardias (those that use an accessory pathway).
It is often difficult to determine whether an atrial tachycardia is of an automatic or a triggered mechanism. The focality of this arrhythmia, however, is pivotal to its management. In making the diagnosis of an atrial tachycardia, it is often important to dissociate the atrium from the ventricle and show that the ventricle is not a critical component of the circuit.
This chapter shows an atrial tachycardia with AV block present with more atrial electrograms than ventricular electrograms. In addition, when adenosine (an AV nodal blocking agent) is given to patients in atrial tachycardia, the tachycardia may at times terminate; however, it almost never terminates with an atrial electrogram. The termination of the tachycardia with an atrial electrogram almost certainly rules out an atrial tachycardia as a diagnosis during an electrophysiology study.