title: Atypical Surface ECG Complicating the Diagnosis of Bundle Branch Reentry Tachycardia.
abstract: BACKGROUND
  Typical left bundle branch block (LBBB) during ventricular tachycardia (VT) is a diagnostic criterion of bundle branch reentry tachycardia (BBRT) with activation of the right bundle in the anterograde direction.
  
  
  RESULTS
  Eleven patients (seven male, 60 ± 12 years) with nonischemic cardiomyopathy (left ventricular ejection fraction 37 ± 16%) presenting with BBRT were successfully treated by ablation of the right bundle. Among them, five patients had atypical surface electrocardiograms (ECGs) differing from a typical LBBB during the VT. Three patients with severe enlargement and dysfunction of the left ventricle had broadened irregular QRS complexes with rR or RS configuration in lead V6 during the BBRT. Two patients with enlargement and/or hypokinesia of the right ventricle had entirely or almost entirely negative complexes (QS) in the chest leads (V1-V6) during the VT. Activation mapping in these two patients revealed that the exit site of the BBRT was in the anterior right ventricle generating a negative concordance in the precordial leads.
  
  
  CONCLUSIONS
  Atypical surface ECGs with broadened irregular QRS complexes or negative concordance in the precordial leads can complicate the correct diagnosis of BBRT in patients with severe left ventricular dysfunction and involvement of the right ventricle.
authors.affiliation: Medizinische Klinik 1, HELIOS Klinikum München-West, Akademisches Lehrkrankenhaus der Universität München, München, Germany.
authors.forename: Christopher
authors.initials: C
authors.lastname: Reithmann
authors.affiliation: Medizinische Klinik 1, HELIOS Klinikum München-West, Akademisches Lehrkrankenhaus der Universität München, München, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Herkommer
authors.affiliation: Innere Medizin, ASKLEPIOS Stadtklinik Bad Tölz, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Remp
authors.affiliation: Medizinische Klinik 1, HELIOS Klinikum München-West, Akademisches Lehrkrankenhaus der Universität München, München, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Fiek
mesh_terms: D000328:Adult; D000368:Aged; D002037:Bundle-Branch Block / Q000150:complications / Q000175:diagnosis* / Q000601:surgery*; D003937:Diagnosis, Differential; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000150:complications / Q000175:diagnosis* / Q000601:surgery*; D016896:Treatment Outcome
keywords: ECG; ablation; bundle branch reentry; implantable cardioverter defibrillator; nonischemic cardiomyopathy; ventricular tachycardia