title: Intra-His bundle block. Clinical, electrocardiographic, and electrophysiologic characteristics.
abstract: OBJECTIVE
  To assess the clinical, electrocardiographic, and electrophysiologic characteristics of patients (pt) with intra-His bundle block undergoing an electrophysiologic study (EPS).
  
  
  METHODS
  We analyzed the characteristics of 16 pt with second-degree atrioventricular block and symptoms of syncope or dyspnea, or both, undergoing conventional EPS.
  
  
  RESULTS
  Intra-His bundle block was documented in 16 pt during an EPS. In 15 (94%) pt, the atrioventricular block was recorded in sinus rhythm; 4 (25%) pt had intra-His Wenckebach phenomenon, which correlated with Mobitz I (MI) atrioventricular block on the electrocardiogram. Seven (44%) pt had 2:1 atrioventricular block, 2 of whom were asymptomatic (12.5%). One (6%) pt had intra- and infra-His bundle block. Clinically, 11 (68%) pt had syncope or presyncope, 3 (18%) had dyspnea on exertion, and 2 (12.5%) were asymptomatic. Eight (50%) pt had bundle-branch block as follows: 4 (25%) pt had left bundle-branch block, and 4 (25%) had right bundle-branch block. Left anterosuperior divisional block was observed in 3 pt (19%), 2 of whom with associated right bundle-branch block.
  
  
  CONCLUSIONS
  Intra-His bundle block was observed in 11% of the pt with second-degree atrioventricular block, syncope or presyncope, or both, it being the most frequent clinical presentation. Intra-His bundle block was more common in the elderly (> 60 years) and among females. The most frequent electrocardiographic presentations were second-degree Mobitz I or type 2:1 atrioventricular block.
authors.affiliation: Hospital Universitário Clementino Fraga Filho - UFRJ, Instituto Estadual de Cardiologia Aloysia de Castro, Rio de Janeiro, RJ, Brazil. eandrea@openlink.com.br
authors.forename: Eduardo M
authors.initials: EM
authors.lastname: Andrea
authors.forename: Jacob
authors.initials: J
authors.lastname: Atie
authors.forename: Washington A
authors.initials: WA
authors.lastname: Maciel
authors.forename: Nilson A
authors.initials: NA
authors.lastname: de Oliveira
authors.forename: Luiz Eduardo
authors.initials: LE
authors.lastname: Camanho
authors.forename: Luís Gustavo
authors.initials: LG
authors.lastname: Belo
authors.forename: Hecio Affonso
authors.initials: HA
authors.lastname: de Carvalho
authors.forename: Leonardo
authors.initials: L
authors.lastname: Siqueira
authors.forename: Eduardo
authors.initials: E
authors.lastname: Saad
authors.forename: Ana Claudia
authors.initials: AC
authors.lastname: Venancio
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002037:Bundle-Branch Block / Q000150:complications / Q000503:physiopathology*; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013575:Syncope / Q000209:etiology / Q000503:physiopathology