title: Pace mapping of Koch's triangle reduces risk of atrioventricular block during ablation of atrioventricular nodal reentrant tachycardia.
abstract: BACKGROUND
  Slow pathway (SP) ablation of AV nodal reentrant tachycardia (AVNRT) can be complicated by second- to third-degree AV block. We assessed the usefulness of pace mapping of Koch's triangle in preventing this complication.
  
  
  RESULTS
  Nine hundred nine consecutive patients undergoing radiofrequency ablation of AVNRT were analyzed. Group 1 (n=487) underwent conventional slow pathway ablation. Group 2 (n=422) underwent ablation guided by pace mapping of Koch's triangle, which located the anterogradely conducting fast pathway (AFP) based on the shortest St-H interval obtained by stimulating the anteroseptal, midseptal, and posteroseptal aspects of Koch's triangle. In group 2, AFP was anteroseptal in 384 (91%), midseptal in 33 (7.8%), and posteroseptal or absent in 5 (1.2%). In 32 of 33 patients with midseptal AFP, slow pathway ablation was performed strictly in the posteroseptal area. In 4 of 5 patients with posteroseptal or no AFP, retrograde fast pathway was ablated. Two patients refused ablation. Persistent second- to third-degree AV block was induced in 7 (1.4%) of 487 group 1 patients versus 0 (0%) of 422 group 2 patients (P=0.038). Ablation was successful in all patients in whom ablation was performed.
  
  
  CONCLUSIONS
  Pace mapping of Koch's triangle identifies patients in whom the AFP is absent or is abnormally close to the slow pathway. In these cases, guiding ablation helps to avoid AV block.
authors.affiliation: Operative Unit of Cardiology, Hospitals of Conegliano, Italy. pdelise@ulss7pieve.veneto.it
authors.forename: Pietro
authors.initials: P
authors.lastname: Delise
authors.forename: Nadir
authors.initials: N
authors.lastname: Sitta
authors.forename: Aldo
authors.initials: A
authors.lastname: Bonso
authors.forename: Leonardo
authors.initials: L
authors.lastname: Coro'
authors.forename: Mauro
authors.initials: M
authors.lastname: Fantinel
authors.forename: Roberto
authors.initials: R
authors.lastname: Mantovan
authors.forename: Luigi
authors.initials: L
authors.lastname: Sciarra
authors.forename: Franco
authors.initials: F
authors.lastname: Zoppo
authors.forename: Roberto
authors.initials: R
authors.lastname: Verlato
authors.forename: Elena
authors.initials: E
authors.lastname: Marras
authors.forename: Daniele
authors.initials: D
authors.lastname: D'Este
mesh_terms: D002304:Cardiac Pacing, Artificial / Q000379:methods / Q000706:statistics & numerical data; D017115:Catheter Ablation / Q000379:methods* / Q000706:statistics & numerical data*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006327:Heart Block / Q000453:epidemiology* / Q000517:prevention & control; D006801:Humans; D015994:Incidence; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D025321:Surgery, Computer-Assisted / Q000379:methods; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000453:epidemiology* / Q000601:surgery*