title: Right bundle branch block and impaired left ventricular function as evidence of a left ventricular conduction delay.
abstract: BACKGROUND
  The indications and efficacy of cardiac resynchronization therapy (CRT) have not been sufficiently clarified in patients with right bundle branch block (RBBB).
  
  
  RESULTS
  This study included 55 patients with normal QRS morphology and duration (Control-Gr) and 49 patients with complete RBBB (CRBBB-Gr). Using tissue Doppler imaging, the time difference (TD) between the electromechanical delay of the septal wall, left ventricular (LV) lateral wall, and right ventricular free wall were measured. Using tissue tracking imaging, the coefficient of the time variation from the beginning of the QRS to the peak displacement time of 6 regions of the LV (CV-PMDLV) was calculated. The TD between the septal wall and that of the LV lateral wall (TDSEPT-LAT) did not differ between the Control-Gr and RBBB-Gr. However, a significant difference was found in the TDSEPT-LAT between the CRBBB patients with LV systolic dysfunction (ejection fraction (EF) < or =50%) and those with normal LV function (EF >50%; p<0.001). The CV-PMDLV was greater in the CRBBB patients with LV systolic dysfunction than in those with a normal LV function (p<0.05). The RBBB-Gr patients with LV dysfunction and a great TDSEPT-LAT, improved clinically after the CRT.
  
  
  CONCLUSIONS
  The presence of RBBB and LV dysfunction may indicate LV dyssynchrony and a heterogeneous mechanical dysfunction.
authors.affiliation: Division of Cardiology, Gunma Prefectural Cardiovascular Center, Maebashi, Japan. htada@umich.edu
authors.forename: Hiroto
authors.initials: H
authors.lastname: Takamatsu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tada
authors.forename: Hiroki
authors.initials: H
authors.lastname: Okaniwa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Toide
authors.forename: Hiroko
authors.initials: H
authors.lastname: Maruyama
authors.forename: Rumi
authors.initials: R
authors.lastname: Higuchi
authors.forename: Kenichi
authors.initials: K
authors.lastname: Kaseno
authors.forename: Shigeto
authors.initials: S
authors.lastname: Naito
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kurabayashi
authors.forename: Shigeru
authors.initials: S
authors.lastname: Oshima
authors.forename: Koichi
authors.initials: K
authors.lastname: Taniguchi
mesh_terms: D000328:Adult; D000368:Aged; D002037:Bundle-Branch Block / Q000503:physiopathology* / Q000628:therapy; D002304:Cardiac Pacing, Artificial; D016022:Case-Control Studies; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology* / Q000628:therapy