title: The relationship between electrical axis by 12-lead electrocardiogram and anatomical axis of the heart by cardiac magnetic resonance in healthy subjects.
abstract: BACKGROUND
  The traditional assumption has been that there is a close relationship between the electrical and anatomical axes of the heart. The aim of this study was to test the hypothesis that there is a correlation between the electrical and anatomical axes of the heart, in both the frontal and transverse planes, in healthy subjects.
  
  
  METHODS
  Ninety-four healthy volunteers (48 men, 46 women; age 21-82 years) were studied by cardiac magnetic resonance and 12-lead electrocardiogram. The anatomical axis was determined by cardiac magnetic resonance and projected onto the frontal and transverse orthogonal planes for comparison with the electrical axis in the corresponding planes.
  
  
  RESULTS
  The electrical and anatomical axes were in the same range in the frontal plane (mean +/- SD, +39 degrees +/- 31 degrees and +38 degrees +/- 10 degrees), but in different ranges in the transverse plane (mean +/- SD, -30 degrees +/- 18 degrees and +46 degrees +/- 7 degrees). The partial correlation coefficients between electrical and anatomical axes were r = 0.30 (P < .01) and r = 0.14 (P = NS) in the frontal and transverse planes, respectively. Age was more strongly correlated to electrical axis than to anatomical axis in the frontal plane.
  
  
  CONCLUSIONS
  There is only a weak correlation between electrical and anatomical axes in the frontal plane and no correlation in the transverse plane. The change of electrical axis with increased age is not explained only by change in the anatomical axis. The results suggest that there is no simple relationship between the electrical and anatomical axes of the heart.
authors.affiliation: Department of Clinical Physiology, Lund University Hospital, Lund, Sweden.
authors.forename: Henrik
authors.initials: H
authors.lastname: Engblom
authors.forename: John E
authors.initials: JE
authors.lastname: Foster
authors.forename: Thomas N
authors.initials: TN
authors.lastname: Martin
authors.forename: Bjoern
authors.initials: B
authors.lastname: Groenning
authors.forename: Olle
authors.initials: O
authors.lastname: Pahlm
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Dargie
authors.forename: Galen S
authors.initials: GS
authors.lastname: Wagner
authors.forename: Håkan
authors.initials: H
authors.lastname: Arheden
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004562:Electrocardiography; D004566:Electrodes; D004867:Equipment Design; D005260:Female; D006321:Heart / Q000033:anatomy & histology* / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012016:Reference Values