title: A modified Lewis ECG lead system for ambulatory monitoring of atrial arrhythmias.
abstract: BACKGROUND
  When using a reduced ECG lead system with three leads or less, the analysis of atrial activity during arrhythmias can become problematic due to low signal amplitude and noise. Long ago, Sir Thomas Lewis proposed a lead system for atrial activity enhancement in which two electrodes are placed directly on the chest, however, these leads are sensitive to arm movement artifacts. In this study, a modified Lewis lead system is proposed that is better suited for ambulatory applications since the electrodes are placed in areas with less muscle.
  
  
  METHODS
  The proposed modification is compared to the original Lewis leads as well as to the ES lead of the EASI system. Forty-one healthy volunteers and 10 patients with atrial fibrillation participated.
  
  
  RESULTS
  The modified Lewis lead has nearly 3 times as large atrial amplitude as the original Lewis leads, and is associated with the largest amplitude of atrial activity when compared to the amplitude of electromyographic activity in healthy volunteers.
  
  
  CONCLUSIONS
  The results suggest that the proposed modification of the Lewis lead system has potential to improve ambulatory monitoring of atrial arrhythmias.
authors.affiliation: Biomedical Engineering Institute, Kaunas University of Technology, Kaunas, Lithuania. Electronic address: andrius.petrenas@ktu.lt.
authors.forename: A
authors.initials: A
authors.lastname: Petrėnas
authors.affiliation: Biomedical Engineering Institute, Kaunas University of Technology, Kaunas, Lithuania; Faculty of Electrical and Electronics Engineering, Kaunas University of Technology, Kaunas, Lithuania.
authors.forename: V
authors.initials: V
authors.lastname: Marozas
authors.affiliation: Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors.forename: G
authors.initials: G
authors.lastname: Jaruševičius
authors.affiliation: Department of Biomedical Engineering and Center of Integrative Electrocardiology, Lund University, Lund, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Sörnmo
mesh_terms: D000328:Adult; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000503:physiopathology; D004562:Electrocardiography / Q000379:methods*; D004566:Electrodes; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000295:instrumentation*; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation
keywords: Atrial activity enhancement; Atrial fibrillation; Lewis ECG lead system