ECG Case 053

Elderly patient presenting with nausea and palpitations. Interpret the ECG.

TOP 100 ECG QUIZ LITFL 053

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.

ECG Atrial flutter variable block rhythm strip
Recurring RR intervals in flutter with variable block



CLINICAL PEARLS

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.


TOP 100 ECG SERIES



Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

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