The characteristic features demonstrated here include a rapid, regular atrial rate between 100 and 250 beats per minute; P waves that are either upright or inverted in lead II; and a constant PR interval for those beats that are conducted . In this case, there is 2:1 block, with an atrial rate of 170 per minute, and the ventricle responding to every other P wave at a rate of 85 per minute.

Atrial tachycardia with block is frequently due to digitalis intoxication.