Elderly patient presenting with nausea and palpitations. Interpret the ECG.
Describe and interpret this ECG
ECG ANSWER and INTERPRETATION
This rhythm is frequently misidentified as atrial fibrillation. However, note in this case:
- Well-defined sawtooth waves in II, III, aVF with regular rate (~300bpm) and consistent morphology.
- Positive flutter waves (“pseudo-P waves”) in V1-2.
- The rhythm is not irregularly irregular. There are repeating patterns of identical R-R intervals that crop up throughout the rhythm strip, corresponding to AV conduction ratios of either 2:1 or 4:1.
This is atrial flutter with a variable block.
Misidentifying this rhythm as AF is not normally a big problem as both conditions are managed similarly — i.e. rate control, anticoagulation.
However, flutter will cardiovert with lower energy than AF — e.g. 50 j compared with 100-200 j.