Types of Atrial Flutter

Atrial flutter is a form of re-entry tachycardia where the circuit is almost always confined to the right atrium: rare left atrial cases have been reported.

Type 1 or typical atrial flutter will have an atrial rate of around 300 bpm (250-350 bpm) and most commonly produces a negative sawtooth appearance in inferior leads II, III and aVF.

The ECG shows Type 1, typical atrial flutter, counterclockwise, with 4:1 block:

Reverse typical flutter produces a positive sawtooth in the inferior leads at around the same rate, and is due to the electrical impulses passing round the re-entry circuit in the reverse direction.

Type 2 or atypical atrial flutter is rare, faster, 350-450 bpm and arises from a different pathway.

The atrial rate can be slowed by Class 1A, 1C drugs and amiodarone. Patients already taking these drugs may present with rates of around 200/min, and sometimes the AV node then allows 1:1 transmission, resulting in a ventricular rate of 200 bpm or so.