title: How to avoid development of AV block during RF ablation: anatomical and electrophysiological analyses at the time of AV node ablation.
abstract: BACKGROUND
  With an aim to identify risk factors that can serve for prevention of atrioventricular (AV) block (AVB) during radiofrequency (RF) ablation, we conducted anatomical and electrophysiological investigations at the time of AV node ablation (AVNA).
  
  
  RESULTS
  Ten patients who underwent AVNA were enrolled. RF energy was delivered from posterior region of septal annulus of the tricuspid valve to the His bundle potential (HBP) recording site using a stepwise approach. In each delivery, atrial/ventricle potential amplitude ratio (A/V ratio), HBP, and juctional ectopy (JE) that appeared during RF delivery were evaluated. Furthermore, fluoroscopic distance between ablation site and HBP recording site (anatomical H-ABL distance) and electrophysiological H-ABL interval were measured. HBP was recorded in 25 of total 70 RF deliveries. When HBP was recorded, the A/V ratio was significantly greater in the group with AVB than without AVB (1.6 ± 2.3 mV vs 0.1 ± 0.2 mV, P = 0.02). The minimum cycle length (CL) of JE was significantly shorter in the group with AVB than without AVB (438 ± 112 ms vs 557 ± 178, ms, P = 0.04). AVB developed frequently when H-ABL distance was less than 15 mm from right anterior oblique view 30° and 12 mm from left anterior oblique view 45° and when H-ABL interval was less than 10 ms. AVB did not develop over the above values.
  
  
  CONCLUSIONS
  HBP with high A/V ratio, JE with short CL, short H-ABL distance, and short H-ABL interval of less than 10 ms should be avoided to prevent AVB during RF ablation at the near site of AV node.
authors.affiliation: Department of Internal Medicine, Division of Cardio-Vascular Medicine, Kurume University School of Medicine, Kurume, Japan.
authors.forename: Takeki
authors.initials: T
authors.lastname: Gondo
authors.forename: Teruhisa
authors.initials: T
authors.lastname: Yoshida
authors.forename: Tomohito
authors.initials: T
authors.lastname: Inage
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Takeuchi
authors.forename: Yujiro
authors.initials: Y
authors.lastname: Fukuda
authors.forename: Eiichi
authors.initials: E
authors.lastname: Takii
authors.forename: Go
authors.initials: G
authors.lastname: Haraguchi
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Imaizumi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D054537:Atrioventricular Block / Q000175:diagnosis / Q000209:etiology* / Q000517:prevention & control*; D001283:Atrioventricular Node / Q000601:surgery*; D018780:Body Surface Potential Mapping / Q000379:methods*; D017115:Catheter Ablation / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D016896:Treatment Outcome