The atrial rate during atrial flutter is between 250 and 350 bpm. At this rate, the AV node is usually refractory long enough to block at least every other beat from conducting to the ventricles.

Atrial flutter occurs when a “reentrant” circuit is present, causing a repeated loop of electrical activity to depolarize the atrium at a rate of about 250 to 350 beats per minute; the atrial ...

Harbaugh has what's called an atrial flutter, which is a type of arrhythmia ... These scars help block abnormal electrical impulses and prevent abnormal rhythms." Per the Cleveland Clinic ...