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Woman with alternating QRS in the emergency department: what is happening?
  1. Miguel Angel Lopez-Lizarraga1,
  2. Alejandro Ezquerra-Osorio1,
  3. Angel Cueva-Parra2
  1. 1 Cardiology, Instituto Nacional de Cardiologia Ignacio Chavez, Mexico City, Mexico
  2. 2 Department of Electrophysiology, Instituto Nacional de Cardiologia Ignacio Chavez, Mexico City, Mexico
  1. Correspondence to Dr Miguel Angel Lopez-Lizarraga, Cardiology, Instituto Nacional de Cardiologia Ignacio Chavez, Mexico City, Mexico; drlopezlizarraga{at}gmail.com

https://doi.org/10.1136/heartjnl-2022-321623

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    Clinical introduction

    A woman in her 40s presented to the emergency department with symptoms of frequent palpitations and fatigue. She had a medical history of systemic arterial hypertension under treatment with nifedipine. Her physical examination was unremarkable. An ECG is obtained and is shown in Figure 1.

    Figure 1

    ECG.

    Question

    How would you interpret the present electrocardiographic findings?

    1. Intermittent pre-excitation.

    2. Ventricular bigeminy.

    3. Alternating right and left bundle branch block.

    4. Bidirectional ventricular tachycardia.

    Answer: A

    Answer A, intermittent pre-excitation.

    The atrial rhythm is sinus at a rate of 85 bpm, the P–P and R–R interval is fixed. The A–V conduction ratio is 1:1; there is a variability of PR from 160 to 110 ms. With alternating QRS morphology, the …

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    Footnotes

    • Contributors All authors contributed equally.

    • 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.

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