Atrial Flutter with 1:1 conduction then 2:1 conduction

Atrial Flutter with 1:1 conduction
Atrial Flutter with 1:1 conduction

On this ECG we see Narrow Complex Tachycardia at a rate of almost 300/min.

The differential for this kind of fast tachycardia would be PSVT (AVRT ot AVNRT) and Atrial Flutter with 1:1 conduction.

You should always think of 1:1 Atrial Flutter when the rate is close to 300/min, and 2:1 Atrial Flutter when the rate is 150/min.

On this second ECG the diagnosis of Atrial Flutter is confirmed.

Atrial Flutter with 2:1 Conduction
Atrial Flutter with 2:1 Conduction

On this ECG the QRS rate is 150/min with P waves at a rate of 300/min best seen in Lead V1 as positive deflections, and in Lead II as negative deflections, so the rhythm is Atrial Flutter with 2:1 Conduction.

This second ECG is evidence that the rhythm in the first ECG is Atrial Flutter with 1:1 conduction.

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