Rhythm originating in the atrium at a rate of 250-350 bpm.
(These rates reflect the rate of atrial beats and not necessarily the rate of the ventricular beats (e.g., There may be atrial fibrillation with a rapid ventricular response indicating the atrial rate is > 350 bpm, and the ventricular rate is > 100 bpm)).
Atrial Flutter and ventricular response:
Ventricular response <60 BPM A-flutter with slow ventricular response.
Ventricular response 60-100 BPM A-flutter with controlled ventricular response.
Ventricular response >100 BPM A-flutter with rapid ventricular response.