Netherlands Heart Journal

, Volume 27, Issue 2, pp 108–109 | Cite as

An irregular narrow complex tachycardia: atrial fibrillation or something else?

  • M. J. MulderEmail author
  • C. P. Allaart
  • H. A. Hauer
  • M. J. B. Kemme
Open Access
Rhythm Puzzle – Question
A 44-year-old female patient was referred to our centre for pulmonary vein isolation. Her medical history was significant for hypothyroidism. She was taking levothyroxine and was clinically euthyroid with a free T4 of 19.9 pmol/l (12–22 pmol/l) and a thyroid-stimulating hormone level of 4.5 mU/l (0.3–4.5 mU/l). She experienced daily episodes of palpitations, not responding to antiarrhythmic drug therapy (sotalol or flecainide). Episodes were self-terminating within an hour of onset, without performing vagal manoeuvres. A 12-lead electrocardiogram was acquired during palpitations, which revealed an irregular narrow complex tachycardia that was previously diagnosed as atrial fibrillation (Fig. 1). Structural heart disease was excluded by transthoracic echocardiography. Based on this ECG an electrophysiology study was scheduled. During placement of the catheters, spontaneous initiation of an irregular tachycardia occurred (Fig. 2). What is the mechanism of this tachycardia?
Fig. 1

Electrocardiogram during palpitations

Fig. 2

Tachycardia during electrophysiology study (CSd distal coronary sinus, CSp proximal coronary sinus, HISd distal His bundle, HISp proximal His bundle, RV right ventricle)


You will find the answer elsewhere in this issue.

Copyright information

© The Author(s) 2018

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Authors and Affiliations

  • M. J. Mulder
    • 1
    Email author
  • C. P. Allaart
    • 1
  • H. A. Hauer
    • 1
    • 2
  • M. J. B. Kemme
    • 1
  1. 1.Department of Cardiology, Amsterdam UMC, Amsterdam Cardiovascular SciencesVrije Universiteit AmsterdamAmsterdamThe Netherlands
  2. 2.Cardiology Centres of the NetherlandsAmsterdamThe Netherlands

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