title: Gender effects on novel time domain parameters of ventricular repolarization inhomogeneity.
abstract: BACKGROUND
  Parameters of ventricular repolarization variability are increasingly being used in an attempt to understand better and predict the occurrence of ventricular tachycardia. Nevertheless, some of the measures used have thus far not been analyzed regarding gender differences in a large group of healthy subjects. Furthermore, new parameters might give further insight.
  
  
  RESULTS
  We investigated 139 healthy volunteers (mean age 41.6 +/- 15.3 years, range 20-77, median 40.0 years, 76 women) without evidence of organic cardiac disease. Mean RR interval and established time domain parameters of heart rate variability (rMSSD; SDNN) were measured for each subject. Beat-to-beat QT interval and time-domain QT interval variability were analyzed. Characteristics of the QT interval and QT interval variability were determined as hourly mean values. The standard deviation of all QT intervals/hour (SDQT) and the standard deviation of all QTc intervals/hour (SDQTc) were used to measure QT interval variability. Four novel ratios of repolarization inhomogeneity (VRI: SDQT/SDNN; VR II: SDQT/rMSSD; VR III: SDQTc/SDNN; VR IV: SDQTc/rMSSD) were introduced. Female subjects exhibited significantly higher values in all four ratios of variability.
  
  
  CONCLUSIONS
  The obvious gender differences in repolarization inhomogeneity found in this study might be valuable in better understanding differences between men and women in the genesis of ventricular tachycardia.
authors.affiliation: Medizinische Klinik II, Universität zu Lübeck, Lübeck, Germany.
authors.forename: Thomas Timothy
authors.initials: TT
authors.lastname: Krauss
authors.forename: Wanda
authors.initials: W
authors.lastname: Mäuser
authors.forename: Michael
authors.initials: M
authors.lastname: Reppel
authors.forename: Heribert
authors.initials: H
authors.lastname: Schunkert
authors.forename: Hendrik
authors.initials: H
authors.lastname: Bonnemeier
mesh_terms: D000328:Adult; D000368:Aged; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006329:Heart Conduction System / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012737:Sex Factors; D016276:Ventricular Function / Q000502:physiology*; D055815:Young Adult