title: Atrial fibrillation propagates through gaps in ablation lines: implications for ablative treatment of atrial fibrillation.
abstract: BACKGROUND
  It has been hypothesized that atrial lesions must be transmural to successfully cure atrial fibrillation (AF). However, ablation lines often do not extend completely across the atrial wall.
  
  
  OBJECTIVE
  The purpose of this study was to determine the effect of residual gaps on conduction properties of atrial tissue.
  
  
  METHODS
  Canine right atria (n = 13) were isolated, perfused, and mounted on a 250-lead electrode plaque. The atria were divided with a bipolar radiofrequency ablation clamp, leaving a gap that was progressively narrowed. Conduction velocities at varying pacing rates and AF frequencies were measured before and after ablations. AF was induced with an extra stimulus and acetylcholine.
  
  
  RESULTS
  Gap widths from 11.2 to 1.1 mm were examined. Conduction velocities through gaps were dependent cycle length (P = .002) and gap size (P <.001). Overall, 253 (97%) of a total of 260 gaps allowed paced propagation; 51 (91%) of 56 gaps 1-3 mm in width permitted paced propagation, as did 202 (99%) of 204 gaps >or=3.0 mm. Similarly, 253 (97%) of a total of 260 gaps allowed propagation of AF. For AF, 51 (93%) of 55 gaps 1-3 mm allowed AF to pass through, as did 202 (99%) of 205 gaps >or=3.0 mm. Gaps as small as 1.1 mm conducted paced and AF impulses.
  
  
  CONCLUSIONS
  Conduction velocities were slowed through residual gaps. However, propagation of wave fronts during pacing and AF occurred through the majority of residual gaps, down to sizes as small as 1.1 mm. Leaving viable tissue in ablation lines for the treatment of AF could account for failures.
authors.affiliation: Department of Surgery, Division of Cardiothoracic Surgery, Washington University in St. Louis School of Medicine and Barnes Jewish Hospital, St. Louis, Missouri 63110, USA.
authors.forename: Spencer J
authors.initials: SJ
authors.lastname: Melby
authors.forename: Anson M
authors.initials: AM
authors.lastname: Lee
authors.forename: Andreas
authors.initials: A
authors.lastname: Zierer
authors.forename: Scott P
authors.initials: SP
authors.lastname: Kaiser
authors.forename: Masha J
authors.initials: MJ
authors.lastname: Livhits
authors.forename: John P
authors.initials: JP
authors.lastname: Boineau
authors.forename: Richard B
authors.initials: RB
authors.lastname: Schuessler
authors.forename: Ralph J
authors.initials: RJ
authors.lastname: Damiano
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000628:therapy*; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods; D004195:Disease Models, Animal; D004285:Dogs; D004594:Electrophysiology; D006325:Heart Atria / Q000473:pathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D010865:Pilot Projects
references.citation: Heart Rhythm. 2004 Dec;1(6):676-83
references.pmid: 15851239
references.citation: J Interv Card Electrophysiol. 2000 Apr;4(1):273-81
references.pmid: 10729848
references.citation: Ann Thorac Surg. 2003 Sep;76(3):836-41; discussion 841-2
references.pmid: 12963212
references.citation: J Thorac Cardiovasc Surg. 2003 Jul;126(1):254-62
references.pmid: 12878963
references.citation: Eur Heart J. 2005 Sep;26(17):1797-803
references.pmid: 15855195
references.citation: Circulation. 1987 Sep;76(3):637-47
references.pmid: 3621524
references.citation: Ann Thorac Surg. 2002 Oct;74(4):S1307-11
references.pmid: 12400806
references.citation: Arch Intern Med. 1995 Mar 13;155(5):469-73
references.pmid: 7864703
references.citation: Circulation. 1998 Jun 2;97(21):2136-45
references.pmid: 9626174
references.citation: Ann Thorac Surg. 2006 Jan;81(1):72-6
references.pmid: 16368338
references.citation: Circulation. 2005 Aug 30;112(9 Suppl):I7-13
references.pmid: 16159868
references.citation: Ann Thorac Surg. 2001 Sep;72(3):S1096-9
references.pmid: 11565732
references.citation: Ann Thorac Surg. 1996 Dec;62(6):1796-800
references.pmid: 8957389
references.citation: Circulation. 2005 Mar 8;111(9):1100-5
references.pmid: 15723973
references.citation: J Cardiovasc Electrophysiol. 1999 Mar;10(3):378-86
references.pmid: 10210501
references.citation: Circulation. 1998 Mar 31;97(12):1176-85
references.pmid: 9537344
references.citation: J Thorac Cardiovasc Surg. 1991 Apr;101(4):569-83
references.pmid: 2008095
references.citation: J Thorac Cardiovasc Surg. 2003 Dec;126(6):1822-8
references.pmid: 14688693
references.citation: Circ Res. 1992 Nov;71(5):1254-67
references.pmid: 1394883
references.citation: J Cardiovasc Electrophysiol. 1996 Dec;7(12):1132-44
references.pmid: 8985802