View source for Five Years of Palpitations

{{NHJ|
|mainauthor= '''N.M. Panhuyzen-Goedkoop, L.R.C. Dekker, A.A.M. Wilde'''
|edition= 2007:06,231
}}
[[Image:Puzzle_2007_6_231_fig1.jpg|Figure 1|thumb]]

A 43-year-old man came to the outpatient clinic for
preventive cardiovascular (CV) screening. During
the last five years he complained of sudden onset of
regular rapid palpitations during and after maximal
exertion with dyspnoea. While holding his breath and
working on abdominal muscular contractions he
succeeded in ceasing these palpitations. This happened
only a few times a year, but had been progressive in
frequency and duration in the last six months. He had
never collapsed during or after these palpitations. A
cause had never been documented. His leisure time
physical activity (6 hours/week) was long-distance
running, fighting sports and fitness. There were no
CV risk factors. His family history was negative. On
physical examination his blood pressure was 125/85
mmHg, and there were no abnormal murmurs or heart
sounds. Bicycle exercise testing (protocol 75 watts for
five minutes, stepwise increment with 25 watts every
minute) was normal (275 watts). Thereafter, a
modified protocol starting at 75 watts for five minutes
with instantaneous increase to 275 watts revealed the
onset of a broad complex tachycardia (figure 1) with
his usual symptoms. After ceasing and working on ‘his
manoeuvre’ he managed to stop the tachycardia. In the
12-lead ECG the same episode is shown in the
extremity leads (left side) and in the precordial leads
(right side). 

'''What is your diagnosis?'''

[[Puzzle_2007_6_231_Answer|Answer]]