title: Utility of the surface electrocardiogram for confirming right ventricular septal pacing: validation using electroanatomical mapping.
abstract: OBJECTIVE
  When targeting the interventricular septum during pacemaker implantation, the lead may inadvertently be positioned on the anterior wall due to imprecise fluoroscopic landmarks. Surface electrocardiogram (ECG) criteria of the paced QRS complex (e.g. negativity in lead I) have been proposed to confirm a septal position, but these criteria have not been properly validated. Our aim was to investigate whether the paced QRS complex may be used to confirm septal lead position.
  
  
  METHODS
  Anatomical reconstruction of the right ventricle was performed using a NavX® system in 31 patients (70 ± 11 years, 26 males) to validate pacing sites. Surface 12-lead ECGs were analysed by digital callipers and compared while pacing from a para-Hissian position, from the mid-septum, and from the anterior free wall.
  
  
  RESULTS
  Duration of the QRS complex was not significantly shorter when pacing from the mid-septum compared with the other sites. QRS axis was significantly less vertical during mid-septal pacing (18 ± 51°) compared with para-Hissian (38 ± 37°, P = 0.028) and anterior (53 ± 55°, P = 0.003) pacing, and QRS transition was intermediate (4.8 ± 1.3 vs. 3.8 ± 1.3, P < 0.001, and vs. 5.4 ± 0.9, P = 0.045, respectively), although no cut-offs could reliably distinguish sites. A negative QRS or the presence of a q-wave in lead I tended to be more frequent with anterior than with mid-septal pacing (9/31 vs. 3/31, P = 0.2 and 8/31 vs. 1/31, P = 1.0, respectively).
  
  
  CONCLUSIONS
  No single ECG criterion could reliably distinguish pacing the mid-septum from the anterior wall. In particular, a negative QRS complex in lead I is an inaccurate criterion for validating septal pacing.
authors.affiliation: Cardiology Service, University Hospital, 4, rue Gabrielle-Perret-Gentil, 1211 Geneva 14, Switzerland. haran.burri@hcuge.ch
authors.forename: Haran
authors.initials: H
authors.lastname: Burri
authors.forename: Chan-Il
authors.initials: CI
authors.lastname: Park
authors.forename: Marc
authors.initials: M
authors.lastname: Zimmermann
authors.forename: Pascale
authors.initials: P
authors.lastname: Gentil-Baron
authors.forename: Carine
authors.initials: C
authors.lastname: Stettler
authors.forename: Henri
authors.initials: H
authors.lastname: Sunthorn
authors.forename: Giulia
authors.initials: G
authors.lastname: Domenichini
authors.forename: Dipen
authors.initials: D
authors.lastname: Shah
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018780:Body Surface Potential Mapping / Q000379:methods*; D002311:Cardiomyopathy, Dilated / Q000473:pathology / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000473:pathology / Q000503:physiopathology; D006331:Heart Diseases / Q000473:pathology / Q000503:physiopathology*; D006349:Heart Valve Diseases / Q000473:pathology / Q000503:physiopathology; D006352:Heart Ventricles / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000473:pathology / Q000503:physiopathology; D011446:Prospective Studies; D054088:Ventricular Septum / Q000473:pathology / Q000503:physiopathology*