No formal diagnostic criteria exist. A diagnosis of<unk>  is primarily one of exclusion, and the following may be observed: * Exclusion of all other causes of<unk>  tachycardia * Common forms of supraventricular tachycardia (SVT) must be excluded * Normal P wave morphology * A resting<unk>  tachycardia is usually (but not always) present * Nocturnal dip in heart rate *<unk>  heart rate response on exertion * Mean heart rate in 24hrs >95 bpm * Symptoms are documented to be due to tachycardia * Hypotension is occasionally observed * Syncope (fainting) is occasionally reported
Inappropriate sinus tachycardia
Ventricular escape beat
AV nodal reentrant tachycardia
Junctional ectopic tachycardia
Sinoatrial arrest
Junctional tachycardia
Second-degree atrioventricular block
Wandering atrial pacemaker