title: Brugada syndrome behind complete right bundle-branch block.
abstract: BACKGROUND
  The characteristic ECG of Brugada syndrome (BS) can be masked by complete right bundle-branch block (CRBBB) and exposed by resolution of the block or pharmacological or pacing maneuvers.
  
  
  RESULTS
  The study consisted of 11 patients who had BS and CRBBB. BS was diagnosed before the development of CRBBB, on the resolution of CRBBB, or from new characteristic ST-segment changes that could be attributable to BS. Structural heart diseases were excluded, and coronary spasm was excluded on the basis of a provocation test at catheterization. In 7 patients, BS was diagnosed before the development of CRBBB. BS was diagnosed when CRBBB resolved spontaneously (n=1) or by right ventricular pacing (n=3). The precipitating cause for the spontaneous resolution of CRBBB, however, was not apparent. On repeated ECGs, new additional upward-convex ST-segment elevation was found in V2 or V3 in 3 patients. In 2 patients, new ST-segment elevation was induced by class IC drugs. The QRS duration was more prolonged in patients with BS and CRBBB compared with age- and sex-matched controls: 170±13 versus 145±15 milliseconds in V1 and 144±19 versus 128±7 milliseconds in V5 (both P<0.0001). The amplitude of R in V1 was smaller [corrected] in the BS patients than in the control subjects (P=0.0323), but that of R' was similar (P=0.0560).
  
  
  CONCLUSIONS
  BS can coexist behind CRBBB, and CRBBB can completely mask BS. BS might be demonstrated by relief of CRBBB or by spontaneous or drug-induced ST-segment elevation. The prevalence, mechanism, and clinical significance of a combination of CRBBB and BS are yet to be determined.
authors.affiliation: Department of Cardiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, Japan. yoshiyaaizawa-circ@umin.ac.jp.
authors.forename: Yoshiyasu
authors.initials: Y
authors.lastname: Aizawa
authors.forename: Seiji
authors.initials: S
authors.lastname: Takatsuki
authors.forename: Motoaki
authors.initials: M
authors.lastname: Sano
authors.forename: Takehiro
authors.initials: T
authors.lastname: Kimura
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nishiyama
authors.forename: Kotaro
authors.initials: K
authors.lastname: Fukumoto
authors.forename: Yoko
authors.initials: Y
authors.lastname: Tanimoto
authors.forename: Kojiro
authors.initials: K
authors.lastname: Tanimoto
authors.forename: Mitsushige
authors.initials: M
authors.lastname: Murata
authors.forename: Takashi
authors.initials: T
authors.lastname: Komatsu
authors.forename: Hideo
authors.initials: H
authors.lastname: Mitamura
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ogawa
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Funazaki
authors.forename: Masahito
authors.initials: M
authors.lastname: Sato
authors.forename: Yoshifusa
authors.initials: Y
authors.lastname: Aizawa
authors.forename: Keiichi
authors.initials: K
authors.lastname: Fukuda
mesh_terms: D000328:Adult; D000368:Aged; D053840:Brugada Syndrome / Q000175:diagnosis* / Q000503:physiopathology*; D002037:Bundle-Branch Block / Q000175:diagnosis* / Q000503:physiopathology*; D004562:Electrocardiography / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D055815:Young Adult
keywords: Brugada syndrome; bundle-branch block; cardiac pacing, artificial; sodium channels