title: The diagnostic criteria for classic parasystole.
abstract: OBJECTIVE
  To establish a diagnostic criteria of parasystole with high sensitivity and high specificity.
  
  
  METHODS
  After excluded from nonparasystole and each variant parasystoles, based on the electrocardiographic data obtained from 61 patients with classic parasystole, we selected the quantitative indices which could reflect the features of ectopic focus with complete entrance block as the diagnostic criteria for parasystole.
  
  
  RESULTS
  The common features of the electrocardiograms of this group were: 1) Take the earliest recorded eight interectopic intervals in which at least four intervals containing sinus beats or other beats having activated to the area within the ectopic focus. When in case of deficiency, it will fill up a vacancy in order. The ratios of the shortest coupling interval to the shortest ectopic cycle length (ECL) were all less than 80%; 2) The coefficients of variation of the eight ECLs were all less than 6%; 3) The maximal differences of coupling intervals were all equal to or more than 0.11 second.
  
  
  CONCLUSIONS
  Three quantitative indices as necessary conditions have been used as diagnostic criteria for parasystole with high sensitivity and high specificity.
authors.affiliation: Department of Cardiovascular Medicine, Second Affiliated Hospital, Zhejiang University Medical School, Hangzhou 310009, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Ren
authors.forename: J
authors.initials: J
authors.lastname: Zhou
authors.forename: G
authors.initials: G
authors.lastname: Xu
authors.forename: T
authors.initials: T
authors.lastname: Xian
authors.forename: L
authors.initials: L
authors.lastname: Xie
authors.forename: Y
authors.initials: Y
authors.lastname: Zhuang
mesh_terms: D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D017574:Parasystole / Q000175:diagnosis*; D012015:Reference Standards; D012680:Sensitivity and Specificity