title: Electrophysiology of a gap created on the canine atrium.
abstract: OBJECTIVE
  It is crucial to detect the unablated regions (="gap") in the radiofrequency linear ablation of atrial tachyarrhythmias. The purpose of this study was to examine the relationship between the electropysiological properties of the gap created in the canine atrium and its anatomicohistologic findings.
  
  
  RESULTS
  In 17 dogs, a linear epicardial radiofrequency ablation lesion was created on the right atrial wall with a gap of surviving tissue in the mid-portion of the lesion. For each gap, the local electrogram (LE) from the gap and conduction pattern through the gap were recorded using an electrode catheter and a plaque electrode during pacing from each side of the gap and the gap size was measured. The gaps >5 mm exhibited a conductive property and the gaps <3 mm had no conduction property according to 3-D mapping. The size of the conductive gaps was larger than that of the non-conductive gaps (7.1 +/- 2.6 vs. 2.6 +/- 2.5 mm, p < 0.0001). The LE configurations were categorized into single, double and continuous potentials and single potentials were demonstrated only in wide gaps >7 mm. There was a significant inversed correlation between the duration of the LE and gap size and also between the LE duration and the conduction velocity. Histological examination showed that the conduction properties through the gap depended mainly on its size.
  
  
  CONCLUSIONS
  The conductivity through the gap, which was affected by the size of the gap, may be evaluated by the duration and configuration of the local electrogram recorded from the gap.
authors.affiliation: Department of Cardiovascular Medicine, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Yano
authors.forename: Kenzo
authors.initials: K
authors.lastname: Hirao
authors.forename: Tomoe
authors.initials: T
authors.lastname: Horikawa
authors.forename: Michio
authors.initials: M
authors.lastname: Tanaka
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Isobe
mesh_terms: D000200:Action Potentials; D000818:Animals; D018780:Body Surface Potential Mapping; D017115:Catheter Ablation; D004285:Dogs; D006325:Heart Atria / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*; D006329:Heart Conduction System / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*