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| [[Puzzle_2006_12_436_Answer|Answer]] | | [[Puzzle_2006_12_436_Answer|Answer]] |
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| The ECG shows sinus rhythm at a rate of 90 beats/
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| min. Conduction intervals are normal (PR 120 ms,
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| QRS 90 ms). Aspecific repolarisation abnormalities
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| (terminal negative T waves in the left lateral and inferior
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| leads) are observed. These are more frequently seen in
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| patients with Friedreich’s ataxia and do not seem to have
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| any particular meaning.
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| There are four wide QRS complexes, one recorded
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| in the extremity leads and three in the precordial leads.
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| Given the similar configuration in lead II (rhythm strip
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| at the bottom) the 1st aberrant QRS complex is
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| probably similar to the 3rd aberrant QRS complex.
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| These complexes are preceded by a short PR interval
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| and ventricular pre-excitation is suggested. The 2nd and
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| 4th aberrant complexes are wider and not preceded
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| by a discernable P wave. Both are followed by a complete
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| compensatory pause suggesting that these complexes
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| have a ventricular origin. The question that
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| subsequently arises is whether all four wide QRS
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| complexes are ventricular extrasystoles or whether both
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| pre-excited complexes and ventricular premature beats
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| are present.
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| If pre-excitation is suggested then the approximate
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| site of pre-excitation should be given. In this case the
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| suggested Δ-wave is positive in leads I, II and III but
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| negative in leads aVR and aVL. The latter combination
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| is actually impossible with pre-excitation and this makes
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| a ventricular extrasystole originating from the right
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| ventricular outflow track, fused with ventricular
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| activation through the normal conduction system
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| (following the regular P-wave) more likely. Indeed,
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| the initial part of the other wide complexes is similar
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| to the initial morphology of the ‘pre-excited’ complexes.
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| A more likely diagnosis therefore is ventricular
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| extrasystoles with different coupling intervals (and
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| fusion in the 1st and 3rd complex).
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