title: Incidence and pathophysiology of atrioventricular block following mitral valve replacement and ring annuloplasty.
abstract: BACKGROUND
  In this retrospective study we evaluate the causative mechanisms underlying postoperative atrioventricular block (AVB) following mitral valve replacement and mitral valve annuloplasty.
  
  
  METHODS
  Between January 1990 and December 2003, 391 patients underwent mitral valve replacement or ring annuloplasty and quadrangular resection. Exclusion criteria were preoperative AV block, two or three valvular procedures, reoperations and procedures combined with coronary artery bypass grafting. The presence of the postoperative AVB was compared with preoperative and intraoperative variables. On 55 post-mortem specimens the relationship between the AV node, AV node artery and mitral valve annulus was investigated.
  
  
  RESULTS
  The mean age was 59+/-14 years and 44% of patients were female. Postoperatively AVB occurred in 92 (23.5%) patients. AVB III was found in 17 (4%) patents, in whom a pacemaker was implanted within median interval of 4 days. Second degree AVB occurred and first degree AVB in five (1.3%) and in 70 (18%) patients respectively. In dry dissected human hearts in 23% of investigated cases the AV node artery was discovered to run close to the annulus of the mitral valve.
  
  
  CONCLUSIONS
  Data collected in this study showed that, sotalol and amiodarone as well as a prolonged cross-clamp time may slightly influence the 23% incidence of postoperative AVB. The morphological investigation showed that the AV node artery runs in close proximity to the annulus in 23% of cases. We speculate that damage of the AV node artery may play a role in development of AVB.
authors.affiliation: Department of Cardiovascular Surgery, University Hospital Zürich, Zurich, Switzerland. denis.berdajs@bluewin.ch <denis.berdajs@bluewin.ch>
authors.forename: Denis
authors.initials: D
authors.lastname: Berdajs
authors.forename: Ulrich P
authors.initials: UP
authors.lastname: Schurr
authors.forename: Antonia
authors.initials: A
authors.lastname: Wagner
authors.forename: Burkhardt
authors.initials: B
authors.lastname: Seifert
authors.forename: Marko I
authors.initials: MI
authors.lastname: Turina
authors.forename: Michele
authors.initials: M
authors.lastname: Genoni
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000638:Amiodarone / Q000009:adverse effects; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects; D001158:Arteries / Q000033:anatomy & histology; D054537:Atrioventricular Block / Q000209:etiology* / Q000503:physiopathology / Q000628:therapy; D001283:Atrioventricular Node / Q000033:anatomy & histology; D002648:Child; D003250:Constriction; D004812:Epidemiologic Methods; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000033:anatomy & histology / Q000601:surgery*; D008944:Mitral Valve Insufficiency / Q000209:etiology / Q000601:surgery*; D010138:Pacemaker, Artificial; D011183:Postoperative Complications; D013015:Sotalol / Q000009:adverse effects
chemical_list: D000889:Anti-Arrhythmia Agents; D013015:Sotalol; D000638:Amiodarone