title: The optimal lead insertion depth for esophageal ECG recordings with respect to atrial signal quality.
abstract: BACKGROUND
  Diagnosing supraventricular arrhythmias by conventional long-term ECG can be cumbersome because of poor p-waves. Esophageal long-term electrocardiography (eECG) has an excellent sensitivity for atrial signals and may overcome this limitation. However, the optimal lead insertion depth (OLID) is not known.
  
  
  METHODS
  We registered eECGs at different lead insertion depths in 27 patients and analyzed 199,716 atrial complexes with respect to signal amplitude and slope. Correlation and regression analyses were used to find a criterion for OLID.
  
  
  RESULTS
  Atrial signal amplitudes and slopes significantly depend on lead insertion depth. OLID correlates with body height (rSpearman=0.71) and can be estimated by OLID [cm]=0.25*body height[cm]-7cm. At this insertion depth, we recorded the largest esophageal atrial signal amplitudes (1.27±0.86mV), which were much larger compared to conventional surface lead II (0.19±0.10mV, p<0.0001).
  
  
  CONCLUSIONS
  The OLID depends on body height and can be calculated by a simple regression formula.
authors.affiliation: ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Haeberlin
authors.forename: Thomas
authors.initials: T
authors.lastname: Niederhauser
authors.forename: Thanks
authors.initials: T
authors.lastname: Marisa
authors.forename: Josef
authors.initials: J
authors.lastname: Goette
authors.forename: Marcel
authors.initials: M
authors.lastname: Jacoment
authors.forename: Daniel
authors.initials: D
authors.lastname: Mattle
authors.forename: Laurent
authors.initials: L
authors.lastname: Roten
authors.forename: Juerg
authors.initials: J
authors.lastname: Fuhrer
authors.forename: Hildegard
authors.initials: H
authors.lastname: Tanner
authors.forename: Rolf
authors.initials: R
authors.lastname: Vogel
mesh_terms: D000328:Adult; D001281:Atrial Fibrillation / Q000175:diagnosis*; D004562:Electrocardiography / Q000295:instrumentation* / Q000379:methods*; D004567:Electrodes, Implanted; D004947:Esophagus / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D019919:Prosthesis Implantation / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity