Atrial Flutter Over Time

What is the rhythm?

Figure 1 

This is a regular narrow QRS complex rhythm at a ventricular rate of about 88 bpm. Distinct P waves can be seen in V1 at a PP interval of about 320 ms or a rate of about 187 bpm. If we rely on atrial rate alone then the rate falls under atrial tachycardia. Most textbooks would say that atrial flutter has a rate of about 250-350 bpm. 

 

These 3 ECG strips from the same patient spanning over a year. Drugs given were digoxin and diltiazem. The first ECG is the latest.

12 Lead ECG

This is the cropped image of lead II from the 4 ECG strips. The top being in the oldest strip and the bottom being the latest strip.

Lead II (combo)

This is the V1 combo.

V1 (combo)

It is obvious from lead II that this is atrial flutter. However, it is interesting to see the P to P rate change as seen from V1 perspective. From the top the PP is about 5 small squares (~300 bpm) to about 8 small squares (~187 bpm). So, in the presence of drugs (atrial myopathy), the atrial rate in patients with atrial flutter could decrease to the level described for atrial tachycardia. So, the atrial rate is not a good parameter to use whether a rhythm is atrial tachycardia or atrial flutter.

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