title: Atrial ischemia promotes atrial fibrillation in dogs.
abstract: BACKGROUND
  Coronary artery disease is a significant risk factor for atrial fibrillation (AF), but the basis for this association is incompletely understood. The present study evaluated the hypothesis that atrial ischemia can create a substrate for AF maintenance.
  
  
  RESULTS
  Atrial ischemia was induced by occlusion of an atrial arterial branch that did not provide blood flow to the ventricles. Atrial-arterial occlusion increased the duration of AF induced by burst pacing from 57+/-32 seconds (control) to 803+/-214 seconds (P<0.001) after 0.5 hour of occlusion and to 887+/-209 seconds (P<0.001) after 3 hours of occlusion. Prolonged AF (>20 minutes) was induced in 0 of 16 dogs (0%) under control conditions, 7 of 16 (44%, P<0.01) at 0.5 to 3 hours, and 5 of 13 (38%, P<0.01) 3 to 5 hours after occlusion. Atrial conduction was slowed substantially within the ischemic zone: eg, conduction delay was 8+/-1 ms at a cycle length of 200 ms, control, versus 22+/-5 ms (P<0.01) after 0.5 hours and 27+/-5 ms (P<0.001) after 3 hours of ischemia. Refractoriness was initially unaffected but was prolonged 5 hours after occlusion. Phase-delay analysis and high-density mapping confirmed severe conduction slowing in the ischemic zone. Histological examination confirmed the location of ischemic regions and revealed extensive ischemia-induced necrosis at sites of conduction delay.
  
  
  CONCLUSIONS
  Experimental atrial ischemia creates a substrate for AF maintenance, apparently by causing local conduction slowing that promotes reentry. These results suggest that atrial ischemia may significantly promote AF, and may be relevant to AF mechanisms in association with coronary artery disease.
authors.affiliation: Department of Medicine, Montreal Heart Institute and University of Montreal, Montreal, Quebec, Canada.
authors.forename: Hani
authors.initials: H
authors.lastname: Sinno
authors.forename: Katayoun
authors.initials: K
authors.lastname: Derakhchan
authors.forename: Danielle
authors.initials: D
authors.lastname: Libersan
authors.forename: Yahye
authors.initials: Y
authors.lastname: Merhi
authors.forename: Tack Ki
authors.initials: TK
authors.lastname: Leung
authors.forename: Stanley
authors.initials: S
authors.lastname: Nattel
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology; D001281:Atrial Fibrillation / Q000209:etiology* / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial; D004285:Dogs; D004594:Electrophysiology; D006325:Heart Atria / Q000503:physiopathology; D007700:Kinetics; D017202:Myocardial Ischemia / Q000150:complications* / Q000473:pathology