title: Experimental studies of atrial fibrillation: a comparison of two pacing models.
abstract: Rapid ventricular pacing (RVP) is a well-established animal model of atrial fibrillation (AF). However, this model is limited by a high mortality rate and severe heart failure. The purpose of our study was to assess a new canine model of inducible AF. We performed acute, short-term, simultaneous atrioventricular pacing (SAVP) and RVP (in random order) in 14 dogs for 30 s. SAVP produced more echocardiographic pulmonary venous flow reversal, a greater increase in mean pulmonary capillary wedge pressure, and a significantly greater decrease in left atrial emptying function (-84.4 +/- 38.6% vs. -23.7 +/- 27.1%, P < 0.05) than RVP. Thirty dogs were randomized to three, longer-term, study groups: eight dogs in the control group (no pacing), eight dogs in the RVP group (2 wk at 240 beats/min followed by 3 wk at 220 beats/min), and fourteen dogs in the SAVP group (2 wk at 220 beats/min). SAVP induced less left ventricular dysfunction but more left atrial dysfunction than RVP. SAVP dogs had similar atrial effective refractory periods as RVP dogs but more heterogeneity in conduction and more AF inducibility (83% vs. 40%, P < 0.05) and maintenance (median 1,660 vs. 710 s, P < 0.05) than RVP dogs. SAVP induced more collagen turnover and was associated with a significantly greater increase in type III collagen in the atria compared with RVP dogs (6.9 +/- 1.5 vs. 4.8 +/- 1.6, respectively, P < 0.05 vs. 1.1 +/- 0.7 in unpaced control dogs). In conclusion, the SAVP model induced profound mechanical and substrate atrial remodeling and reproducible sustained AF. This new model is clinically relevant and may be useful for testing AF interventions.
authors.affiliation: Keenan Research Center, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Laurent
authors.forename: Gordon
authors.initials: G
authors.lastname: Moe
authors.forename: Xudong
authors.initials: X
authors.lastname: Hu
authors.forename: Howard
authors.initials: H
authors.lastname: Leong-Poi
authors.forename: Kim A
authors.initials: KA
authors.lastname: Connelly
authors.forename: Petsy Pui-Sze
authors.initials: PP
authors.lastname: So
authors.forename: Andrew
authors.initials: A
authors.lastname: Ramadeen
authors.forename: Liia
authors.initials: L
authors.lastname: Doumanovskaia
authors.forename: Andrea
authors.initials: A
authors.lastname: Konig
authors.forename: Judy
authors.initials: J
authors.lastname: Trogadis
authors.forename: David
authors.initials: D
authors.lastname: Courtman
authors.forename: Bradley
authors.initials: B
authors.lastname: Strauss
authors.forename: Paul
authors.initials: P
authors.lastname: Dorian
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology*; D001794:Blood Pressure / Q000502:physiology; D002304:Cardiac Pacing, Artificial; D002311:Cardiomyopathy, Dilated / Q000503:physiopathology; D003094:Collagen / Q000096:biosynthesis / Q000235:genetics; D004285:Dogs; D015150:Echocardiography, Doppler; D017548:Echocardiography, Transesophageal; D004562:Electrocardiography; D004594:Electrophysiology; D018093:Gelatinases / Q000096:biosynthesis / Q000235:genetics; D006339:Heart Rate / Q000502:physiology; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D010138:Pacemaker, Artificial; D011669:Pulmonary Wedge Pressure / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012032:Refractory Period, Electrophysiological / Q000502:physiology; D053773:Transforming Growth Factor beta1 / Q000096:biosynthesis / Q000235:genetics; D020257:Ventricular Remodeling / Q000502:physiology
chemical_list: D012333:RNA, Messenger; D053773:Transforming Growth Factor beta1; D003094:Collagen; D018093:Gelatinases; D020780:Matrix Metalloproteinase 9