RT-203
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Optimizing the second phase
duration of biphasic shocks. Preliminary results of a prospective clinical study
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Béla Merkely, Andrzej Lubinski*,
Tibor Gyöngy, E. Lewicka-Nowak*, Ferenc Horkay, G. Swiatecka*, Orsolya Kiss, László
Gelléer, Elek Bodor, Jürgen Pilz**, Max Schaldach**.
Dept. of Cardiovascular Surgery, Semmelweis Medical University, Budapest,
Hungary; *Dept. of Cardiology, Medical University of Gdansk, Poland, **Institute for
Biomedical Engineering, Friedrich-Alexander University of Erlangen-Nürnberg, Germany
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Abstract
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In a multicenter, randomized and prospective study,
the defi-brillation efficacy of biphasic pulses with 2 msec vs 5 msec 2nd phases were
compared in 27 patients (age: 56 ± 13 years, male: 81%, coronary artery disease: 66%,
dilatative cardiomyopathy: 15%, EC:\WWW 43 ± 15%, amiodarone: 55%) with a unipolar pectoral
transvenous defibrillation system (fractally coated SPS-lead vs Phylax 06 active housing
-can-, Biotronik) with two 100 µF capacitors. 1st phase parameters for both biphasic
waveforms were: charging voltage 100%, switching voltage 40%. Defibrillation thresholds
with shocks of 2 msec or 5 msec 2nd phases were determined in a random order during
defibrillator implantation. A significant difference was found in charging voltage and
delivered energy at defibrillation threshold between pulse forms with 2 msec and 5 msec
2nd phases using 100 µF capacitors (delivered energy at defibrillation threshold with 5
msec: 9.9 J, with 2 msec: 8.5 J). Twelve patients had a defibrillation threshold decrease
and 3 patients had a defibrillation threshold increase with 2 ms 2nd phases. There was no
difference in the other 12 patients. Mean shock impedance was 65.8 ± 7.3 W. To conclude, reduction of 2nd phase duration seems to improve
overall defibrillation efficacy, and it may be useful to decrease the defibrillation
threshold in individual patients.
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Key Words
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Implantable cardioverter defibrillator –
function, indications
defibrillation efficacy, defibrillation threshold, biphasic shock, OA
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