Document Detail

Relationship between electrocardiographic RR and QT interval variabilities and indices of ventricular function in healthy subjects.
MedLine Citation:
PMID:  18175856     Owner:  NLM     Status:  MEDLINE    
To date there has been no simultaneous characterization of the influence of physical exercise on cardiac ventricular function and cardiac electrical variability. Consequently, little is known about the relationship between the ventricular function and either heart rate (RR) or repolarization (QT) variability. In particular, the relationship between the QT variability index (QTVI) and ventricular function would be of clinical interest. Eight males of similar age (20.7 +/- 0.4 years (mean +/- SD)), mass (78.4 +/- 7.7 kg) and aerobic fitness (50.7 +/- 4.9 ml kg(-1) min(-1)) undertook progressive bicycle exercise. A three-lead Holter ECG was recorded continuously during pre-exercise, exercise and recovery, and mean values of RR and QT, their variabilities (RMSSD and SDNN) and their relative variability (QTVI) were determined. Traditional indices of ventricular function were determined beat to beat via impedance cardiography, and beat-to-beat blood pressure was recorded via photoplethysmography. Multiple linear regression analysis using the stepwise method resulted in significant models for each of the dependent variables (RR, QT, RR and QT variabilities, QTVI), using indices of the ventricular function as predictor variables. Notably, the QTVI reflected both the stroke volume index (SVI) and the acceleration index (ACI), which are measures of cardiac 'output' per contraction and the force of contraction, respectively. This relationship was largely unperturbed by physical exercise, in contrast with the results for all other dependent variables. We conclude that the QTVI is a reasonably consistent measure of the cardiac ventricular function, and as such is a more useful index than other parameters based on RR or QT interval alone.
M J Lewis; A L Short
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Publication Detail:
Type:  Clinical Trial; Journal Article     Date:  2007-12-10
Journal Detail:
Title:  Physiological measurement     Volume:  29     ISSN:  0967-3334     ISO Abbreviation:  Physiol Meas     Publication Date:  2008 Jan 
Date Detail:
Created Date:  2008-01-07     Completed Date:  2008-04-24     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9306921     Medline TA:  Physiol Meas     Country:  England    
Other Details:
Languages:  eng     Pagination:  1-13     Citation Subset:  IM    
School of Human Sciences, Swansea University, Vivian Building, Singleton Park, Swansea SA2 8PP, UK.
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MeSH Terms
Capillary Resistance / physiology
Cardiac Output / physiology
Cardiography, Impedance
Electrocardiography, Ambulatory / methods*
Exercise / physiology*
Exercise Test
Heart / physiology
Heart Rate / physiology*
Linear Models
Stroke Volume / physiology
Ventricular Function / physiology*
Ventricular Function, Left / physiology

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

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