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Cardiac memory refers to a change in
ventricular repolarization induced by and
persisting for minutes to months after cessation
of a period of altered ventricular activation (eg,
resulting from pacing or preexcitation in
patients with Wolff-Parkinson-White syndrome).
ECG imaging (ECGI) is a novel imaging modality
for noninvasive electroanatomic mapping of
epicardial activation and repolarization.
Fourteen pediatric patients with Wolff-Parkinson-White
syndrome and no other congenital disease, were
imaged with ECGI a day before and 45 minutes, 1
week, and 1 month after successful catheter
ablation. ECGI determined that preexcitation
sites were consistent with sites of successful
ablation in all cases to within a 1-hour arc of
each atrioventricular annulus. In the preexcited
rhythm, activation-recovery interval (ARI) was
the longest (349 ± 6 ms) in the area of
preexcitation leading to high average
base-to-apex ARI dispersion of 95 ± 9 ms (normal
is 40 ms). The ARI dispersion remained the same
45 minutes after ablation, although the
activation sequence was restored to normal. ARI
dispersion was still high (79 ± 9 ms) 1 week
later and returned to normal (45 ± 6 ms) 1 month
after ablation.
The study demonstrates that ECGI can
noninvasively localize ventricular insertion
sites of accessory pathways to guide ablation
and evaluate its outcome in pediatric patients
with Wolff-Parkinson-White syndrome.
Wolff-Parkinson-White is associated with high
ARI dispersion in the preexcited rhythm that
persists after ablation and gradually returns to
normal over a period of 1 month, demonstrating
the presence of cardiac memory. The 1-month time
course is consistent with transcriptional
reprogramming and remodeling of ion channels.
Circulation. 2008;118:907-915.
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