Document Detail

Measure of the QT-RR dynamic coupling in patients with the long QT syndrome.
MedLine Citation:
PMID:  23094878     Owner:  NLM     Status:  MEDLINE    
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.
Josef Halamek; Jean-Philippe Couderc; Pavel Jurak; Vlastimil Vondra; Wojciech Zareba; Ivo Viscor; Pavel Leinveber
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     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:  2013-05-16     Revised Date:  2013-10-17    
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.
Institute of Scientific Instruments, AS CR, Brno, Czech Republic.
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MeSH Terms
Adaptation, Physiological
Circadian Rhythm
Cohort Studies
Electrocardiography, Ambulatory / methods*,  statistics & numerical data
Heart Rate
Long QT Syndrome / diagnosis*,  physiopathology*
Reference Values
Young Adult
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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