20-year old patient with sudden onset of palpitations.

What does the rhythm strip demonstrate?

Describe and interpret this ECG


Top rhythm strip

  • Regular narrow complex tachycardia
  • Pseudo-R’ waves (retrograde P waves) are seen deforming the J point

Middle rhythm strip 

  • 12mg adenosine given
  • A salvo of broad and bizarre-looking complexes interrupts the rhythm (this is a common phenomenon during chemical cardioversion with adenosine)

Bottom rhythm strip

  • The patient has reverted to sinus rhythm
  • The pseudo-R’ waves have now disappeared
  • There are no obvious delta waves of WPW, but this should be confirmed on a 12-lead ECG


The 12-lead ECG confirms reversion to sinus rhythm and does not demonstrate any features of WPW. The diagnosis is AV-nodal reentry tachycardia (AVNRT).

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 |

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

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