Document Detail

Delayed paced ventricular activation in the long QT syndrome is associated with ventricular fibrillation.
MedLine Citation:
PMID:  16818204     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: LQTS may cause sudden cardiac death (SCD), but the mechanisms linking gene mutations to ventricular fibrillation (VF) are unclear.
OBJECTIVE: To determine whether ventricular activation delays in congenital long QT syndrome (LQTS) are associated with VF and to describe these delays clinically by measuring activation through ventricular myocardium after a premature extrastimulus.
METHODS: Forty-six patients with LQTS, including 16 with VF (LQTS VF) were investigated, and the results were compared with those from 24 patients with hypertrophic cardiomyopathy and VF (HCM VF). Electrograms in response to premature stimuli were analyzed for increases in electrogram duration (DeltaED) and the S1S2 coupling intervals at which electrogram latency starts to increase (S1S2(delay)). Two piecewise continuous straight line segments were fitted to the last electrogram deflection as a function of S1S2 interval in the LQTS and HCM VF populations, and the difference in their gradient (alpha) was taken as an index of the abruptness of the onset of this delay.
RESULTS: Thirteen LQTS VF and six LQTS non-VF patients had values of DeltaED and S1S2(delay) comparable to those in HCM VF patients, while the remainder (three LQTS VF and 24 LQTS non-VF) had lower values (P<.001). There was only a weak correlation between delay and the corrected QT interval. The HCM and LQTS VF patients could be separated by the value of alpha (P<.01), with the LQTS patients having a more abrupt onset of delay.
CONCLUSIONS: Large delays in ventricular activation after an extrastimulus occur in patients with the LQTS, especially those with VF. The change in delay is abrupt in the LQTS, indicating sudden block to activation creating a dynamic substrate for arrhythmogenesis.
Richard C Saumarez; Mariusz Pytkowski; Maciej Sterlinski; Richard N W Hauer; Richard Derksen; Martin D Lowe; Hannah Szwed; Christopher L-H Huang; David E Ward; A John Camm; Andrew A Grace
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-03-16
Journal Detail:
Title:  Heart rhythm : the official journal of the Heart Rhythm Society     Volume:  3     ISSN:  1547-5271     ISO Abbreviation:  Heart Rhythm     Publication Date:  2006 Jul 
Date Detail:
Created Date:  2006-07-04     Completed Date:  2006-11-07     Revised Date:  2014-02-19    
Medline Journal Info:
Nlm Unique ID:  101200317     Medline TA:  Heart Rhythm     Country:  United States    
Other Details:
Languages:  eng     Pagination:  771-8     Citation Subset:  IM    
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MeSH Terms
Cardiac Pacing, Artificial / adverse effects*
Follow-Up Studies
Heart Rate / physiology*
Long QT Syndrome / complications,  physiopathology,  therapy*
Middle Aged
Ventricular Fibrillation / etiology*,  physiopathology
Grant Support
G0100186//Medical Research Council; G0100188//Medical Research Council
Comment In:
Heart Rhythm. 2006 Jul;3(7):779-80   [PMID:  16818205 ]

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

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