Question 30.1

This is the ECG of a 62-year-old man undergoing treatment for acute lymphoblastic leukaemia who presented with shortness of breath.

  • What are the abnormalities on this ECG?
  • What is the likely cause of his symptoms?

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College Answer


Atrial fibrillation

Low voltage complexes

Electrical alternans


Pericardial effusion


This of course is not the canonical CICM ECG, it is one which I found by Googling "AF with electrical alternans". Thus, the complexes are not actually "low volage". The presence of alternans is obscured by the irregularity of the AF, but it is still present, particularly if you look at leads V1 and V2.

In ideal conditions, electrical alternans should look like this:

electrical alternans in pericardial effusion

If the rightful owner of this image ever comes forward and demands I take it down, I will be forced to generate this electrical phenomenon in myself. 


Usher, Bruce W., and Richard L. Popp. "Electrical alternans: Mechanism in pericardial effusion." American heart journal 83.4 (1972): 459-463.