Simultaneous right atrioventricular pacing: a novel model to study atrial remodeling and fibrillation in the setting of heart failure.
BACKGROUND
Atrial fibrillation (AF) is a common arrhythmia which contributes to morbidity and mortality in patients with heart failure (HF). Atrial remodeling is a key substrate for the development of AF in HF. However, experimental models that study AF in the setting of HF have important limitations. We evaluated a new dog model of atrial remodeling and AF.


RESULTS
Twenty-two mongrel dogs were randomized into 2 groups: 14 dogs with simultaneous atrioventricular pacing (SAVP) for 2 weeks (220 beats/min, no AV delay) and 8 control dogs with no pacing. SAVP for 2 weeks induced marked changes in atrial mechanical function and conduction. Left atrial area fractional shortening decreased 61 +/- 17%, whereas left ventricular area fractional shortening decreased by 38 +/- 18% from baseline (both P < .05). Conduction slowed and conduction heterogeneity increased. AF was induced in 83% of SAVP dogs, lasting a median of 1600 seconds, versus no dogs with induced AF in the controls. SAVP significantly increased nonfibrillar collagen in the mid-myocardium of both atrial appendages and matrix metalloproteinase-9 activity.


CONCLUSIONS
SAVP in dogs induces structural and electrical remodelling that form the substrate for reproducibly inducible AF. This novel model may be useful for studies of the pathophysiology and treatment of AF in heart failure.
Laurent
Gabriel
G
Division of Cardiology, University of Toronto and Terrence Donnelly Cardiovascular Laboratories, St. Michael's Hospital, Ontario, Canada.
Moe
Gordon W
GW
Hu
Xudong
X
Pui-Sze So
Petsy
P
Ramadeen
Andrew
A
Leong-Poi
Howard
H
Doumanovskaia
Liia
L
Konig
Andrea
A
Trogadis
Judy
J
Courtman
David
D
Strauss
Bradley H
BH
Dorian
Paul
P
D000818:Animals; D001281:Atrial Fibrillation / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D016275:Atrial Function; D001707:Biopsy, Needle; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D016009:Chi-Square Distribution; D003094:Collagen / Q000378:metabolism; D004195:Disease Models, Animal; D004285:Dogs; D015150:Echocardiography, Doppler; D004562:Electrocardiography; D006329:Heart Conduction System; D006333:Heart Failure / Q000150:complications / Q000000981:diagnostic imaging / Q000628:therapy*; D006439:Hemodynamics; D007150:Immunohistochemistry; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D010138:Pacemaker, Artificial; D011336:Probability; D011897:Random Allocation; D016276:Ventricular Function
D003094:Collagen