Out of the frying pan and into the fire

Author(s)	J.M. van Opstal, C.R. Hoorntje, L.M. Rodriguez
NHJ edition:	2004; 5, 234
These Rhythm Puzzles have been published in the Netherlands Heart Journal and are reproduced here under the prevailing creative commons license with permission from the publisher, Bohn Stafleu Van Loghum.
The ECG can be enlarged twice by clicking on the image and it's first enlargement

Figure 1

Figure 2

A 26-year-old pregnant woman was admitted to the emergency heart department with continuous severe palpitations accompanied by chest pain which had started four hours before presentation. She had never had such palpitations before, had no medical history and was not taking any medication. A 12-lead ECG is shown in figure 1.

What is the aetiology of the tachycardia? The paper speed is as usual (25mm/s).

Answer