A Narrow QRS Complex Tachycardia Sensitive to Isoptin: Difference between revisions

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m (New page: {{NHJ| |mainauthor= '''A.A.M. Wilde, R.H. Bakker''' |edition= 2006,08:268 }} Figure 1|thumb Figure 2|thumb A 54...)
 
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[[Puzzle_2006_08_268 Answer|Answer]]
[[Puzzle_2006_08_268 Answer|Answer]]
Figure 1 shows a narrow-complex tachycardia (rate
180 beats/min). The QRS complex is 84 msec wide,
and has an intermediate axis. A P wave is not easy to
discern, but could be present in the mid part of the T
wave (most clearly seen in leads II and aVF). The Pwave
axis cannot be determined. The differential
diagnosis of this tachycardia is orthodromic circus
movement tachycardia, AV-nodal re-entry tachycardia
or atrial tachycardia. The position of the P wave at
some distance from the QRS complex is in favour of
an orthodromic tachycardia (or an atrial tachycardia
with first-degree atrioventricular (AV) block).
Isoptin terminates the tachycardia and that is usually
indicative of involvement of the AV node. Hence, an
orthodromic tachycardia is the most likely diagnosis.
The ECG after termination of the tachycardia (figure
2) showed sinus rhythm with a normal PQ interval
(140 msec), followed by a normal QRS complex in
the first six beats. In the rhythm strip at the bottom of
the panel, the next three QRS complexes are preceded
by the same configuration P wave but with a shorter
PQ interval (90 msec). These QRS complexes start
with a Q wave. In the three precordial leads above the
rhythm strip a discrete Δ-wave is visible (electroneutral
in V1 and positive in leads V2 and V3). In the left
precordial leads (last complex) the Δ-wave changes
from positive (V4) to neutral-negative (V6). Hence,
this ECG shows evidence of intermittent pre-excitation
with a Kent bundle in the inferior wall, presumably
just left of the septum. For the exact location of the Kent
bundle pre-excitation should be present in the
extremity leads.
'''In conclusion, in the presence of (intermittent) preexcitation the tachycardia is most likely an orthodromic re-entrant tachycardia.'''