RT-247
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A method to evaluate
contemporary refractoriness and conduction velocity at different atrial sites during human
atrial fibrillation
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Antonio Michelucci, Luciano
Alcidi*, Silvio Vena, Luigi Padeletti, Maria Cristina Porciani, Pasquale Imperiale*,
Andrea Colella, Salvatore Romano*, Gian Franco Gensini.
Istituto di Clinica Medica Generale e Cardiologia, * Dipartimento di
Fisiopatologia Clinica, Universita di Firenze, Italy
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Abstract
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Background. Evaluation of
electrophysiologic behaviour during human atrial fibrillation has been done so far by
measuring intervals between atrial electrograms. This because a relationship between the
intervals and refractoriness has been proved. A more accurate evaluation, however, needs
also estimation of conduction velocity. In fact both refractoriness and conduction
velocity are necessary to estimate wavelength of circulating impulse which has been proven
able to condition perpetuation or termination of the arrhythmia. Evaluation of conduction
veloci-ty could be done accepting that the duration of the atrial potential is
proportional to the time necessary to atrial impulse to pass over the recording bipolar
electrode. On this basis if the potential is larger, the time is longer and the velocity
is slower; thus we can consider that the conduction velocity correlated inversely with the
width of atrial potential.
Methods. We undertook a computerized analysis of the intra-atrial
potentials during atrial fibrillation in the electrophysiologic study to evaluate
contemporaneously the interval between intra-atrial potentials (f-f intervals, as
expression of local refractoriness) and the width of atrial potentials (f-width, inversely
correlated with the local conduction velocity) by an averaging algorithm if refractoriness
(f-f interval) and conduction velocity (1/f-width) can be measured then wavelength of
atrial impulse could be estimated by calculating the ratio between f-f interval and
f-width. The software allows also evaluation of f-f interval and f-width variability
during the time. Measurement can be done automatically step-by-step (eg every 5 or 10
seconds) for the entire duration of recordings.
Conclusions. This type of evaluation is important considering that
the analysis of human atrial fibrillation presents some limitations because refractory
periods of the local atrial tissue and conduction velocity of atrial impulse cannot be
evaluated so far contemporary and dynamically.
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Key Words
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Atrial fibrillation - electrophisiology
mechanisms of AF perpetuation, computerized analysis of intra-atrial potentials,
refractoriness, conduction velocity, wave-length of circulating impulse, OA
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