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This Article Full Text Full Text (PDF) All Versions of this Article: 294/3/H1206    most recent 00999.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Laurent, G. Articles by Dorian, P. Search for Related Content PubMed PubMed Citation Articles by Laurent, G. Articles by Dorian, P.

Experimental studies of atrial fibrillation: a comparison of two pacing models

¹Keenan Research Center, Li Ka Shing Knowledge Institute, and ²Division of Cardiology, St. Michael's Hospital; ³Department of Medicine, University of Toronto, Toronto, Ontario, Canada; ⁴University of Melbourne, Department of Medicine, St. Vincent's Hospital, Victoria, Australia; ⁵Department of Pharmacology, University of Toronto; ⁶Bio-imaging, St. Michael's Hospital; ⁷Department of Surgery, University of Toronto; ⁸Terrence Donnelly Cardiovascular Laboratories; and ⁹Schulich Heart Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada

Submitted 29 August 2007 ; accepted in final form 3 January 2008

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.

experimental atrial arrhythmia; extracellular matrix; remodeling