title: [Electrocardiographic QRS waves of healthy Chinese population with different ages and sexes].
abstract: OBJECTIVE
  To develop a normal electrocardiographic QRS wave standard in Chinese population with different ages and sexes.
  
  
  METHODS
  Fourteen leads electrocardiographic QRS waves of 4,322 Chinese healthy subjects aged from birth to 85 years old divided into 11 age-groups were analysed and studied.
  
  
  RESULTS
  There were highly significant differences in QRS amplitudes and cardiac electric axes of different ages and sexes. The changes of QRS amplitudes which increased and decreased with advancing age were usually earlier in female than in male. Comparing with QRS waves there were higher QRS amplitudes in girls than in boys in the newborn period; however, it is higher in male than in female in puberty and middle-aged persons. The sex difference was not obvious relatively in small children and the aged. There was significant difference in QRS amplitudes when electrocardiograms of Chinese people compared with those of Westerners.
  
  
  CONCLUSIONS
  A Chinese normal electrocardiographic QRS standard established according to different ages and sexes may be applied clinically.
authors.affiliation: Laboratory of Pediatric Cardiovascular Diseases, Second Affiliated Hospital, Hunan Medical University, Changsha 410011.
authors.forename: Z W
authors.initials: ZW
authors.lastname: Xie
authors.forename: C
authors.initials: C
authors.lastname: Wang
authors.forename: M X
authors.initials: MX
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012737:Sex Factors