title: Vertical displacement of the precordial leads alters electrocardiographic morphology.
abstract: BACKGROUND
  The present study was undertaken to assess whether the vertical displacement of electrodes affects the waveforms of precordial leads.
  
  
  RESULTS
  Two hundred forty healthy, adult volunteers had a standard 12-lead electrocardiogram, a 12-lead electrocardiogram with the precordial leads displaced 2 cm cranially, and another with the precordial leads displaced 2 cm caudally from the standard positions. All the three sets of electrocardiograms were visually compared, and changes noted. One hundred twenty male and 120 female volunteers, 20-68 years of age, were analyzed. Fifty-four males (45.0%) and 2 females (1.7%) showed no difference between the 3 sets of electrocardiograms, while 66 males (55.0%) and 118 females (98.3%) had some changes. R wave amplitude changes were noted in 63 male (52.5%) and 111 female (92.5%) volunteers; S wave amplitude changes were seen in 59 males (49.2%) and 99 females (82.5%,); T wave changes in 5 males (4.2%) and 3 females (2.5%); ST segment changes in 1 male (0.8%) and none of the females; and ORS morphologic changes in 1 male (0.8%) and 12 females (10.0%).
  
  
  CONCLUSIONS
  Precordial electrocardiographic waveform changes were seen with the vertical displacement of the precordial leads. This will have implications on the interpretation of serial electrocardiograms. Healthcare providers should take into consideration this deviation when interpreting serial ECGs.
authors.affiliation: Department of Emergency Medicine, Singapore General Hospital, Singapore. gaefal@sgh.com.sg
authors.forename: Fatimah
authors.initials: F
authors.lastname: Lateef
authors.forename: Narayan
authors.initials: N
authors.lastname: Nimbkar
authors.forename: Zhuang Kun
authors.initials: ZK
authors.lastname: Da
authors.forename: Foo Rui
authors.initials: FR
authors.lastname: Min
mesh_terms: D000328:Adult; D000368:Aged; D016001:Confidence Intervals; D004562:Electrocardiography / Q000295:instrumentation* / Q000379:methods*; D004566:Electrodes; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement; D012016:Reference Values