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Relation between QT interval variability and cardiac sympathetic activity in hypertension.
MedLine Citation:
PMID:  21257917     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Elevated QT interval variability is a predictor of malignant ventricular arrhythmia, but the underlying mechanisms are incompletely understood. A recent study in dogs with pacing-induced heart failure suggests that QT variability is linked to cardiac sympathetic nerve activity. The aim of this study was to determine whether increased cardiac sympathetic activity is associated with increased beat-to-beat QT interval variability in patients with essential hypertension. We recorded resting norepinephrine (NE) spillover into the coronary sinus and single lead short-term high resolution body surface ECG in 23 patients with essential hypertension and nine normotensive control subjects. To assess beat-to-beat QT interval variability we calculated overall QT variability (QTVN) as well as the QT variability index QTVi. Cardiac NE spillover (12.2 ± 6.5 vs. 20.7 ± 14.7, p = 0.03) as well as QTVi (-1.75 ± 0.36 vs. -1.42 ± 0.50, p = 0.05) were significantly increased in hypertensive patients compared to normotensive subjects. QTVN was significantly correlated with cardiac NE spillover (r(2) = 0.31, p = 0.001), RR variability (r(2) = 0.20, p = 0.008) and with systolic blood pressure (r(2) = 0.16, p = 0.02). Linear regression analysis identified the former two as independent predictors of QTVN. In conclusion, elevated repolarisation lability is directly associated with sympathetic cardiac activation in patients with essential hypertension.
Authors:
Mathias Baumert; Markus P Schlaich; Eugene Nalivaiko; Elisabeth A Lambert; Carolina Ika Sari; David M Kaye; Murray David Esler; Prashanthan Sanders; Gavin Lambert
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-1-21
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  -     ISSN:  1522-1539     ISO Abbreviation:  -     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2011-1-24     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
1The University of Adelaide.
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