An Unusual Case of Alternating Ventricular Morphology on the 12-Lead Electrocardiogram

J Emerg Med. 2017 Mar;52(3):348-353. doi: 10.1016/j.jemermed.2016.08.027. Epub 2016 Oct 7.


Background: One of the principal tasks of an emergency physician is identifying potentially life-threatening conditions in the undifferentiated patient; cardiac dysrhythmia is an example of such a condition. A systematic approach to a patient with atypical dysrhythmia enables proper identification of such-life threatening conditions.

Case report: We describe a 31-year-old man presenting to the emergency department with an undifferentiated dysrhythmia after naloxone reversal of an opiate overdose. A systematic approach to the electrocardiogram led to the rare diagnosis of Wolff-Parkinson-White (WPW) alternans. We review the differential diagnosis of this dysrhythmia and the initial evaluation of a patient with the WPW pattern present on their electrocardiogram. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Emergency physicians should be prepared to use a systematic approach to an undifferentiated dysrhythmia to identify potentially life-threatening conditions.

Keywords: ECG; Wolff-Parkinson-White; dysrhythmia.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Electrocardiography / classification*
  • Emergency Service, Hospital / organization & administration
  • Heart Conduction System / abnormalities*
  • Heart Conduction System / physiopathology
  • Heroin Dependence / complications
  • Humans
  • Male
  • Naloxone / pharmacology
  • Naloxone / therapeutic use
  • Narcotic Antagonists / pharmacology
  • Narcotic Antagonists / therapeutic use
  • Wolff-Parkinson-White Syndrome / diagnosis*
  • Wolff-Parkinson-White Syndrome / physiopathology


  • Narcotic Antagonists
  • Naloxone