Atrial flutterAtrial flutter is a rhythm that features flutter waves at a rate around 300 bpm (240-360) that make the baseline resemble a sawtooth pattern. The ventricular rate is often half this rate (~150 bpm), which is known as 2:1 conduction. Medications may slow the conduction to less than 2:1. Rarely there may be 1:1 conduction through the AV node, which can produce dangerously fast ventricular rates.
Atrial flutter is often caused by a re-entry circuit around the tricuspid valve. It is frequently confused with SVT (e.g. AVNRT) or sinus tachycardia. Adenosine can help to diagnose atrial flutter by making the sawtooth flutter waves more obvious at slower rates, but adenosine will not treat it. Lewis leads can also help to unmask atrial activity.