title: Reduced high-frequency QRS components in electrocardiogram leads facing an area of the heart with intraventricular conduction delay due to bundle branch block.
abstract: BACKGROUND
  The mechanisms underlying high-frequency QRS components (HF-QRS) are incompletely understood. One theory is that HF-QRS are related to the conduction velocity of the heart. The purpose was to test this hypothesis by comparing HF-QRS in patients with left or right bundle branch block (LBBB and RBBB, respectively) to those in healthy subjects and in patients with ischemic heart disease (IHD).
  
  
  METHODS
  Twenty-two patients with LBBB, 19 patients with RBBB, 63 normal subjects, and 64 patients with IHD were included. Twelve-lead electrocardiograms were analyzed in the frequency interval 150 to 250 Hz.
  
  
  RESULTS
  The study showed reduced HF-QRS in patients with LBBB compared with healthy subjects and patients with IHD. The difference, however, was small in lead V(1) and V(2). In patients with RBBB, no differences in HF-QRS could be detected except in few leads; among those is lead V(1).
  
  
  CONCLUSIONS
  The results support the theory that HF-QRS are related to the conduction velocity of the heart.
authors.affiliation: Department of Clinical Physiology, Lund University, Lund, Sweden. elin.tragardh@med.lu.se
authors.forename: Elin
authors.initials: E
authors.lastname: Trägårdh
authors.forename: Jonas
authors.initials: J
authors.lastname: Pettersson
authors.forename: Galen S
authors.initials: GS
authors.lastname: Wagner
authors.forename: Olle
authors.initials: O
authors.lastname: Pahlm
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002037:Bundle-Branch Block / Q000150:complications / Q000175:diagnosis*; D002648:Child; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000175:diagnosis*