One is Enough, Two is Too Many

Author(s)	A.A.M. Wilde, R.B.A. van den Brink
NHJ edition:	2005:8,285
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

An otherwise healthy 24-year-old man was referred to our hospital because of drug refractory spells of palpitations accompanied by dizziness. These symptoms recurred several times a month and were terminated with intravenous adenosine. Figures 1 and 2 show the ECGs during palpitations and during normal conditions, respectively.

What is the most likely diagnosis and how can it be treated?

Answer