<unk>  is characterized by an electrocardiogram (ECG) strip with three or more discrete P wave morphologies in the same lead, not including that originating from the sinoatrial node, plus tachycardia, which is a heart rate exceeding 100 beats per minute (although some suggest using a threshold of 90 beats per minute). Furthermore, there should be irregular PP intervals, and the baseline should be isoelectric between P waves. Other findings that are commonly seen, but are not diagnostic include irregular PR and RR intervals. Variation in PR intervals has not been included in the diagnostic criteria because the PR interval varies with the length of the preceding RP interval. Other diagnoses that may present with similar findings on electrocardiogram that should be included in the differential diagnosis include sinus tachycardia with frequent premature<unk>  contractions (this would have regular PP intervals),<unk>  flutter with variable AV node conduction (this would have regular PP intervals and flutter waves),<unk>  fibrillation (this would not have discrete P-wave morphologies), and wandering<unk>  pacemaker which would have a heart rate less than 100 beats per minute). Additional workup If arrhythmia persists despite the treatment of underlying medical conditions it may be worth checking a complete blood count and serum chemistry for signs of infection, anemia, or electrolyte abnormalities such as hypokalemia and hypomagnesemia.
Multifocal atrial tachycardia
Wandering atrial pacemaker
Atrioventricular reentrant tachycardia
AV nodal reentrant tachycardia
Second-degree atrioventricular block
Third-degree atrioventricular block
First-degree atrioventricular block
Sinus arrhythmia