title: Comparison of the spatial QRS-T angle derived from digital ECGs recorded using conventional electrode placement with that derived from Mason-Likar electrode position.
abstract: The spatial QRS-T angle is ideally derived from orthogonal leads. We compared the spatial QRS-T angle derived from orthogonal leads reconstructed from digital 12-lead ECGs and from digital Holter ECGs recorded with the Mason-Likar (M-L) electrode positions.
  
  
  
  Orthogonal leads were constructed by the inverse Dower method and used to calculate spatial QRS-T angle by (1) a vector method and (2) a net amplitude method, in 100 volunteers. Spatial QRS-T angles from standard and M-L ECGs differed significantly (57°±18° vs 48°±20° respectively using net amplitude method and 53°±28° vs 48°±23° respectively by vector method; p<0.001). Difference in amplitudes in leads V4-V6 was also observed between Holter and standard ECGs, probably due to a difference in electrical potential at the central terminal.
  
  
  
  Mean spatial QRS-T angles derived from standard and M-L lead systems differed by 5°-9°. Though statistically significant, these differences may not be clinically significant.
authors.affiliation: Quintiles Cardiac Safety Services, Mumbai, India.
authors.forename: Vaibhav
authors.initials: V
authors.lastname: Salvi
authors.affiliation: Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Elaine
authors.initials: E
authors.lastname: Clark
authors.affiliation: Quintiles Cardiac Safety Services, Mumbai, India.
authors.forename: Dilip R
authors.initials: DR
authors.lastname: Karnad
authors.affiliation: Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Macfarlane
authors.affiliation: Quintiles Cardiac Safety Services, Mumbai, India. Electronic address: gopi.panicker@quintiles.com.
authors.forename: Gopi Krishna
authors.initials: GK
authors.lastname: Panicker
authors.affiliation: Quintiles Cardiac Safety Services, Mumbai, India.
authors.forename: Pooja
authors.initials: P
authors.lastname: Hingorani
authors.affiliation: Quintiles Cardiac Safety Services, Mumbai, India.
authors.forename: Snehal
authors.initials: S
authors.lastname: Kothari
mesh_terms: D003936:Diagnosis, Computer-Assisted / Q000295:instrumentation / Q000592:standards*; D015716:Electrocardiography, Ambulatory / Q000295:instrumentation* / Q000379:methods*; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*
keywords: Body surface potential mapping; Cardiac repolarization; Electrode resistance; Holter electrocardiography; Vectorcardiography