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High-rate pacing reduces variability of repolarization and prevents repolarization-dependent arrhythmias in dogs with chronic AV block.
MedLine Citation:
PMID:  20561108     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
INTRODUCTION: high-rate pacing may have an inhibitory effect on the initiation of Torsade de Pointes arrhythmias (TdP). However, permanent pacing is only indicated in high-risk patients. We performed a proof of concept study into automatic overdrive pacing for prevention of drug-induced TdP, using short-term variability of repolarization (STV) as a feedback parameter of arrhythmic risk.
METHODS AND RESULTS: the minimal signal sampling frequency required for measuring STV was determined through computer simulation. Arrhythmogenic response to dofetilide (25 microg/kg/5 minutes) was tested at two different paced heart rates (60-65 bpm vs 100-110 bpm) in 7 dogs with chronic atrioventricular block, while recording right and left ventricular (LV) monophasic action potential (MAP) and LV electrogram (EGM). Simulations showed a sampling frequency of 500 Hz is sufficient to capture relevant STV values. High-rate pacing prevented dofetilide-induced TdP seen at the low rate (low: 6/7 vs high: 1/7). At the low rate, STV from LV MAP duration increased before occurrence of spontaneous, ectopic activity and TdP (1.7 ± 0.6-3.0 ± 1.8 ms, P < 0.05), but at the high-rate STV did not change significantly (0.9 ± 0.2-1.5 ± 1.4 ms, NS). Regression analysis showed a close relation between STV calculated from LV MAP and from LV EGM (R(2) = 0.71).
CONCLUSIONS: high-rate pacing increases repolarization reserve in dogs with chronic atrioventricular block, preventing dofetilide-induced TdP. Changes in repolarization reserve are reflected in values of STV.
Authors:
Peter Oosterhoff; Morten B Thomsen; Joep N Maas; Nico J M Atteveld; Jet D M Beekman; Harold V M VAN Rijen; Marcel A G VAN DER Heyden; Marc A Vos
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of cardiovascular electrophysiology     Volume:  21     ISSN:  1540-8167     ISO Abbreviation:  J. Cardiovasc. Electrophysiol.     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-12-07     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9010756     Medline TA:  J Cardiovasc Electrophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1384-91     Citation Subset:  IM    
Affiliation:
Medtronic Bakken Research Center, Maastricht, The Netherlands Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, Utrecht, The Netherlands.
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