S-8
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RR variability as a tool in
implanted ICDs to predict tachyarrhythmias
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Gerhard Hoh.
Klinikum Dessau, Abt. Kardiologie, Klinik für Innere Medizin, Dessau, Germany
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Abstract
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Background. Heart rate variability
assesses the autonomic balance of the heart. Certain measures of heart rate variability
can predict the risk of ventricular tachycardia, ventricular fibrillation and sudden death
in specific patient groups. Recently attention is focusing on the mechanisms initiating
episodes of ventricular tachyarrhythmia by analysing the time period immediately preceding
such episodes. These can now be systematically assessed on a routine basis by utilizing
the storage function for RR intervals preceding episodes of ventricular tachyarrhythmia
which is available in some implantable cardioverter defibrillators.
Methods. The purpose of this study is to investigate the suitability
of the new PHYLAX XM (BIOTRONIK Berlin, Germany) implantable cardioverter defibrillator,
which features a storage capacity of 18 000 RR intervals derived from a near field bipolar
right ventricular intracardiac electrogram (IEGM), for accurate determination of changes
in heart rate variability. Simultaneous recordings of a standard surface electrocardiogram
using the Medilog Excel-2 (OXFORD Instruments) and the intracardiac electrogram generated
by the PHYLAX XM are obtained from patients under standardized conditions and subsequently
analysed. Heart rate variability of 5 minute sections of each recording is assessed using
time and frequency domain parameters.
Results. Initial results indicate a close correlation of the heart
rate variability measures derived from analysing the intracardiac electrogram obtained
from the PHYLAX XM and the surface electrogram. However further patients have to be
included in the study before the significance of the results can be statistically
evaluated.
Conclusions. Based on the initial trends we expect the PHYLAX XM to
be a powerful tool to systematically and accurately evaluate the heart rate variability of
patients presenting with a high risk of tachyarrhythmic events who were implanted with a
cardioverter defibrillator. The PHYLAX XM enables the investigation of a time period of
upto four-and-a-half hours preceding the detection of an arrhythmic event and we are
confident that interesting new diagnostic and therapeutic methods can be developed in the
future.
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Key Words
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Implantable cardioverter defibrillator –
function, indications
prediction of arrhythmias, RR variability, OA
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