Document Detail

QT-RR hysteresis is caused by differential autonomic states during exercise and recovery.
MedLine Citation:
PMID:  22542617     Owner:  NLM     Status:  MEDLINE    
QT-RR hysteresis is characterized by longer QT intervals at a given RR interval while heart rates are increasing during exercise and shorter QT intervals at the same RR interval while heart rates are decreasing during recovery. It has been attributed to a lagging QT response to different directional changes in RR interval during exercise and recovery. Twenty control subjects (8 males, age 51 ± 6 yr), 16 subjects with type 2 diabetes (12 males, age 56 ± 8 yr), 71 subjects with coronary artery disease (CAD) and preserved left ventricular ejection fraction (LVEF) (≥50%) (51 males, age 59 ± 12 yr), and 17 CAD subjects with depressed LVEF (<50%) (13 males, age 57 ± 10 yr) underwent two 16-min exercise tests followed by recovery. In session 2, parasympathetic blockade with atropine (0.04 mg/kg) was achieved at end exercise. QT-RR hysteresis was quantified as: 1) the area bounded by the QT-RR relationships for exercise and recovery in the range of the minimum RR interval at peak exercise to the minimum RR interval + 100 ms and 2) the difference in QT interval duration between exercise and recovery at the minimum RR interval achieved during peak exercise plus 50 ms (ΔQT). The effect of parasympathetic blockade was assessed by substituting the QT-RR relationship after parasympathetic blockade. QT-RR hysteresis was positive in all groups at baseline and reversed by parasympathetic blockade (P < 0.01). We conclude that QT-RR hysteresis is not caused by different directional changes in RR interval during exercise and recovery. Instead, it is predominantly mediated by differential autonomic nervous system effects as the heart rate increases during exercise vs. as it decreases during recovery.
Daniel J Pelchovitz; Jason Ng; Alexandru B Chicos; Daniel W Bergner; Jeffrey J Goldberger
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2012-04-27
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  302     ISSN:  1522-1539     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2012 Jun 
Date Detail:
Created Date:  2012-06-18     Completed Date:  2012-09-13     Revised Date:  2013-06-25    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  H2567-73     Citation Subset:  IM    
Division of Cardiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA.
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MeSH Terms
Atropine / pharmacology
Autonomic Nervous System / drug effects,  physiopathology*
Coronary Artery Disease / physiopathology*
Diabetes Mellitus, Type 2 / physiopathology*
Exercise / physiology*
Exercise Test
Heart Rate / drug effects,  physiology*
Middle Aged
Parasympatholytics / pharmacology
Ventricular Dysfunction, Left / physiopathology*
Grant Support
1R01HL-70179-01A2/HL/NHLBI NIH HHS
Reg. No./Substance:
0/Parasympatholytics; 51-55-8/Atropine

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

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