An irregular atrial tachycardia

There are clearly visible P-waves in most of the leads (Fig. 1). The P-waves are negative in leads DII, DIII and aVF. Hence, this is not a sinus rhythm. All the P-waves have the same morphology, constant PP interval at a rate of 210 beats per minute (bpm), with an isoelectric baseline between them. Therefore, the underlying rhythm is unifocal atrial tachycardia [1]