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| [[Puzzle_2005_12_466 - Answer|Answer]] | | [[Puzzle_2005_12_466 - Answer|Answer]] |
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| The patient’s ECG in sinus rhythm demonstrates right
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| bundle branch block, but more remarkably an extreme
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| prolongation and fragmentation of the terminal
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| portion of the QRS complex. In addition, the QRS
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| complex in V1 has an initial Q wave. This combination
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| of findings should suggest significant right ventricular
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| overload and conduction delay. In and of itself, this must
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| suggest some form of right ventricular disease. During
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| tachycardia, QRS morphology is unchanged, indicating
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| supraventricular tachycardia (SVT), but the original
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| P wave is absent. Close examination, as illustrated in
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| figure 3, reveals low amplitude and highly fragmented
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| P waves, negative in V1 with a superior axis, cycle length
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| 280 ms with 3:1 AV conduction. P-wave morphology
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| also indicates right-sided pathology. All in all, this combination
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| of right ventricular conduction abnormality
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| and right atrial tachycardia should suggest a congenital
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| heart defect involving the right heart. This was indeed
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| the case in this patient: she had undergone correction
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| of secundum type atrial septal defect at a young age.
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| More importantly in light of onset of symptoms in
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| 2002, tricuspid valve reconstruction was performed in
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| that year because of Ebstein’s anomaly.
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| Ebstein’s anomaly is a relatively rare condition,
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| accounting for no more than approximately 0.5% of
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| congenital heart defects. It is characterised by an
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| abnormal septal leaflet of the tricuspid valve with apical
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| displacement, leading to atrialisation of part of the right
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| ventricle.<cite>Wu</cite> While morphological and subsequent
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| haemodynamic consequences may be mild, severe
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| tricuspid regurgitation also occurs, as was the case in
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| this patient and the reason for her surgery. Considerable
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| conduction delay in this atrialised and dilated
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| portion of the right ventricle has been demonstrated
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| to cause QRS fragmentation and prolongation in classic
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| electrophysiological studies<cite>Kaster</cite> and more recently signalaveraged
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| ECG;<cite>Tede</cite> figure 1 is a classical example of this
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| phenomenon. Onset of atrial arrhythmias in such close
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| conjunction to cardiac surgery involving right atrial
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| atriotomy must inevitably raise the suspicion of postincisional
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| atrial tachycardia. This diagnosis was confirmed
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| at electrophysiological study.
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| ==References==
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| <biblio>
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| #Wu pmid=15536453
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| #Kastor pmid=1182962
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| #Tede pmid=14969616
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| </biblio>
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