title: Normal limits of ECG measurements related to atrial activity using a modified limb lead system.
abstract: OBJECTIVE
  The present study was designed to derive the normal limits of a new ECG lead system aimed at enhancing the amplitude of atrial potentials through the use of bipolar chest leads.
  
  
  METHODS
  Sixty healthy male subjects, mean age 38.85±8.76 years (range 25 to 58 years) were included in this study. In addition to a standard 12-lead ECG, a modified limb lead (MLL) ECG was recorded for 60 sec with the RA electrode placed in the 3rd right intercostal space slightly to the left of the mid-clavicular line, the LA electrode placed in the 5th right intercostal space slightly to the right of the mid-clavicular line and the LL electrode placed in the 5th right intercostal space on the mid- clavicular line.
  
  
  RESULTS
  In the frontal plane, the modification of limb electrode positions produced significant changes compared to standard limb lead I and II. The mean P wave amplitude was 111±17μV in MLL I and 64±16μV in standard limb lead (SLL) I (p<0.001). Similarly it was 118±22μV in MLL II and 100±27μV in SLL II. No statistically significant changes were seen in V1-V6 due to modification of the Wilson central terminal electrode positions.
  
  
  CONCLUSIONS
  The modification of limb electrode placement leads to changes in the amplitude of the P waves in the MLL leads I and II compared to SLL leads I and II in healthy subjects. These changes may be of importance in the detection of atrial electrical activity.
authors.affiliation: Department of Instrumentation and Control Engineering, National Institute of Technology; Tiruchirappalli-India. mountshiva@gmail.com.
authors.forename: Jayaraman
authors.initials: J
authors.lastname: Sivaraman
authors.forename: Gandhi
authors.initials: G
authors.lastname: Uma
authors.forename: Sangareddi
authors.initials: S
authors.lastname: Venkatesan
authors.forename: Mangalanathan
authors.initials: M
authors.lastname: Umapathy
authors.forename: Vella Elumalai
authors.initials: VE
authors.lastname: Dhandapani
mesh_terms: D000328:Adult; D016275:Atrial Function / Q000502:physiology*; D004562:Electrocardiography; D004566:Electrodes; D005121:Extremities; D006325:Heart Atria; D006801:Humans; D008297:Male; D008875:Middle Aged; D011187:Posture