title: Electrocardiographic features and prevalence of bilateral bundle-branch delay.
abstract: BACKGROUND
  Definitive diagnosis of bilateral bundle-branch delay/block may be made when catheter-induced right bundle-branch block (RBBB) develops in patients with baseline left bundle-branch (LBB) block. We hypothesized that a RBBB pattern with absent S waves in leads I and aVL will identify bilateral bundle-branch delay/block.
  
  
  RESULTS
  Fifty patients developing transient RBBB pattern in lead V1 during right heart catheterization were studied. Patients were grouped according to whether the baseline ECG demonstrated a normal QRS, left fascicular blocks, or LBB block pattern. The RBBB morphologies in each group were compared. The prevalence of bilateral bundle-branch delay/block pattern was examined in our hospital ECG database. All patients with baseline normal QRS complexes (n=30) or left fascicular blocks (4 anterior, 5 posterior) developed a typical RBBB pattern. Among the 11 patients with a baseline LBB block pattern, 7 developed an atypical RBBB pattern with absent S waves in leads I and aVL and the remaining 4 demonstrated a typical RBBB. The absence of S waves in leads I and aVL during RBBB was 100% specific and 64% sensitive for the presence of pre-existing LBB block. Among the consecutive 2253 hospitalized patients with RBBB, 34 (1.5%) had the bilateral bundle-branch delay/block pattern.
  
  
  CONCLUSIONS
  An ECG pattern of RBBB in lead V1 with absent S wave in leads I and aVL indicates concomitant LBB delay. Pure RBBB and bifascicular blocks are associated with S waves in leads I and aVL.
authors.affiliation: From the St. Vincent Medical Group, Indianapolis, IN.
authors.forename: Leonidas
authors.initials: L
authors.lastname: Tzogias
authors.affiliation: From the St. Vincent Medical Group, Indianapolis, IN.
authors.forename: Leonard A
authors.initials: LA
authors.lastname: Steinberg
authors.affiliation: From the St. Vincent Medical Group, Indianapolis, IN.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Williams
authors.affiliation: From the St. Vincent Medical Group, Indianapolis, IN.
authors.forename: Kent E
authors.initials: KE
authors.lastname: Morris
authors.affiliation: From the St. Vincent Medical Group, Indianapolis, IN.
authors.forename: William J
authors.initials: WJ
authors.lastname: Mahlow
authors.affiliation: From the St. Vincent Medical Group, Indianapolis, IN.
authors.forename: Richard I
authors.initials: RI
authors.lastname: Fogel
authors.affiliation: From the St. Vincent Medical Group, Indianapolis, IN.
authors.forename: Jeff A
authors.initials: JA
authors.lastname: Olson
authors.affiliation: From the St. Vincent Medical Group, Indianapolis, IN.
authors.forename: Eric N
authors.initials: EN
authors.lastname: Prystowsky
authors.affiliation: From the St. Vincent Medical Group, Indianapolis, IN. bjpadani@stvincent.org.
authors.forename: Benzy J
authors.initials: BJ
authors.lastname: Padanilam
mesh_terms: D000200:Action Potentials; D000368:Aged; D002037:Bundle-Branch Block / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015995:Prevalence; D012189:Retrospective Studies; D013997:Time Factors
keywords: bundle-branch block; heart block