ECG Case 306 Interpretation

This post is an answer to the ECG Case 306

Key features

  • Regular narrow complex tachycardia 
  • Rate ~ 130 bpm
  • Left axis deviation
  • Late R wave transition
  • Relatively flat isoelectric line
  • Possible atrial activity seen in lead III and V6

Differential diagnosis

  • Atrial flutter
  • Atrial tachycardia
  • Accelerated junctional rhythm

This following ECG was taken during treatment with adenosine, hence the dramatic ventricular pause.

ECG during treatment with adenosine
ECG during treatment with adenosine

Key features

  • Minimum 5.72 sec ventricular pause
  • Evidence of atypical flutter waves
    • Rate ~290 bpm
    • Low voltage
    • Positive in lead V1
  • Following pause initiation of ventricular activity with increasing rate
    • Ventricular 72 bpm (4:1 block) prior to end of ECG tracing
  • QRS morphology sames as ECG above

What happened next ?

The patient’s heart rate rapidly returned to continued in a narrow complex tachycardia as per the first ECG. The patient underwent DCCV under procedural sedation and reverted following a single shock, post cardioversion ECG showed unremarkable normal sinus rhythm.

READ MORE: Atrial Flutter: ECG Interpretation [With Examples]

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