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Peculiar QRS morphology: an electrophysiological phenomenon
  1. Chee Loong Chow1,2,
  2. Om Narayan1,
  3. Han Sung Lim1,2
  1. 1 Cardiology, Northern Hospital, Epping, Victoria, Australia
  2. 2 Medicine, University of Melbourne, Parkville, Victoria, Australia
  1. Correspondence to Dr Chee Loong Chow, Cardiology, Northern Hospital, Epping, VIC 3076, Australia; dominic.c88{at}

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Clinical introduction

A female teenager presented with palpitations.

The baseline rhythm on her ECG demonstrates sinus rhythm with normal PR interval of 120 ms, a mild degree of delta wave, RSR′ morphology in V1 with a precordial transition zone between V1 and V2. The frontal axis demonstrates normal QRS axis, in particular a positive lead III and aVF vectors, and negative aVR and aVL vectors, suggesting an overall inferior propagating QRS vector.

Intermittently, however, she exhibits a different QRS morphology and a different ventricular activation vector (lead III and aVL), annotated with black arrows in figure 1.

Figure 1

ECG of patient illustrating …

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  • Contributors CLC contributed to the conception of idea, write-up, review and finalisation of the manuscript. ON contributed to the review and edits of the manuscript. HSL contributed to the conception of idea, review and edits of the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Provenance and peer review Not commissioned; externally peer reviewed.