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Measure of the QT-RR Dynamic Coupling in Patients with the Long QT Syndrome.
MedLine Citation:
PMID:  23094878     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
Background: The patients with the long QT syndrome type-1 (LQT-1) have an impaired adaptation of the QT interval to heart rate changes. Yet, the description of the dynamic QT-RR coupling in genotyped LQT-1 has never been thoroughly investigated. Method: We propose a method to model the dynamic QT-RR coupling by defining a transfer function characterizing the relationship between a QT interval and its previous RR intervals measured from ambulatory Holter recordings. Three parameters are used to characterize the QT-RR coupling: a fast gain (Gain(F) ), a slow gain (Gain(L) ), and a time constant (τ). We investigated the values of these parameters across genders, and in genotyped LQT-1 patients with normal QTc interval duration (QTc  <  470 ms). Results: The QT-RR dynamic profiles are significantly different between LQT-1 patients (97) and controls (154): LQT-1 have longer QTc interval (453  ± 35 vs. 384  ± 26 ms, P  <  0.0001), and an increased dependency of the QT interval to previous RR changes revealed by a larger Gain(L) (0.22  ± 0.06 vs. 0.18  ± 0.07, P  <  0.0001) and Gain(F) (0.05  ± 0.02 vs. 0.03  ± 0.01, P  <  0.0001). Importantly, LQT-1 patients have a faster QT dynamic response to previous RR changes described by τ: 122  ± 44 vs. 172  ± 92 beats (P  <  0.0001). This faster QT dynamic response of the QT-RR dynamic coupling remained in LQT-1 patients with QTc in a normal range (<430 ms). Conclusions: The measurement of QT-RR dynamic coupling could be used in patients suspected to carry a concealed form of the LQT-1 syndrome, or to provide insights into the types of arrhythmogenic triggers a patient may be prone to.
Authors:
Josef Halamek; Jean-Philippe Couderc; Pavel Jurak; Vlastimil Vondra; Wojciech Zareba; Ivo Viscor; Pavel Leinveber M Sc
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Publication Detail:
Type:  Journal Article     Date:  2012-08-13
Journal Detail:
Title:  Annals of noninvasive electrocardiology : the official journal of the International Society for Holter and Noninvasive Electrocardiology, Inc     Volume:  17     ISSN:  1542-474X     ISO Abbreviation:  Ann Noninvasive Electrocardiol     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-25     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9607443     Medline TA:  Ann Noninvasive Electrocardiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  323-30     Citation Subset:  IM    
Copyright Information:
© 2012, Wiley Periodicals, Inc.
Affiliation:
Institute of Scientific Instruments, AS CR, Brno, Czech Republic Center for Quantitative Electrocardiography and Cardiac Safety, Heart Research Follow-up Program, University of Rochester Medical Center, Rochester, NY, USA International Clinical Research Center, Center of Biomedical Engineering, St. Anne's University Hospital, Brno, Czech Republic.
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