RT-246
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Changes in atrial effective
refractory period in patients with induced atrial fibrillation
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Andrzej Lubinski, Ewa
Lewicka-Nowak, Maciej Kempa, Grzegorz Raczak, Grazyna Swiatecka.
II Department of Cardiology, Medical University of Gdansk, Poland
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Abstract
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There is evidence from recent experimental studies
that pacing-induced atrial fibrillation modifies electrophysiological properties of atria
by shortening of atrial refractory period. The present study was performed to assess the
influence of induced atrial fibrillation (AF) on atrial effective refractory period (ERP)
in patients with structural heart disease.
Method. The study was performed in 7 pts with coronary artery disease
or dilated cardiomyopathy without spontaneous AF episodes in their history. AF was induced
by fast atrial stimulation (300-1500/min). If sinus rhythm restored within 10 min AF was
reinduced. Atrial ERP was measured during atrial pacing at basic cycle length of 550 msec,
before AF induction and after its conversion to the sinus rhythm. After restoration of
sinus rhythm a time course of atrial ERP recovery was assessed.
results. Atrial ERP before AF was 236 ± 22 msec. ERP shortening following AF was observed
after 2 min of AF. After 9 min 30 sec (8 min 40 sec-10 min 50 sec) of AF ERP achieved
minimal value of 145 ± 29 msec. ERP returned to the initial value during 9 min (6-10 min)
after conversion of AF. A tendency to prolongation in duration of consecutive AF episodes
and facilitation of their induction was observed.
Conclusion. The present study confirms that in humans short episodes
of atrial fibrillation may markedly decrease duration of atrial refractoriness. In
patients with structural heart disease atrial ERP shortening after AF was found to be
reversible during approximately 10 min after arrhythmia termination.
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Key Words
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Atrial fibrillation - electrophisiology
pacing-induced AF, atrial effective refractory period, coronary artery disease, dilated
cardiomyopathy, mechanisms of AF perpetuation, OA
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