Document Detail

Atrial and ventricular electrical and contractile remodeling and reverse remodeling owing to short-term pacing-induced atrial fibrillation in horses.
MedLine Citation:
PMID:  19000247     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: In humans, atrial fibrillation (AF) induces electrical, contractile, and structural remodeling leading to AF stabilization. Little is known about AF-induced atrial remodeling in horses. HYPOTHESIS: Induced AF produces rapid atrial electrical and contractile remodeling in horses. ANIMALS: Six horses, 5 animals completed the study. METHODS: Each horse was instrumented with a pulse generator and pacemaker to maintain AF by burst pacing and to study atrial and ventricular electrophysiology (AF cycle length [AFCL], AF duration, and atrial/ventricular effective refractory period [AERP/VERP] at different pacing cycle lengths [PCL]). Left atrial and ventricular contractile remodeling were assessed echocardiographically by calculation of fractional changes in atrial and ventricular dimensions, respectively, during the cardiac cycle. Measurements were performed at baseline, a 7-day AF period and a 2-day recovery period. RESULTS: Atrial electrical and contractile remodeling could be demonstrated after 4 and 12 hours of AF, respectively. A progressive shortening of the AERP (261 +/- 39-171 +/- 18 ms at a PCL of 1,000 ms, P < .0001), an attenuation of the AERP rate adaptation, a decrease in AFCL (239 +/- 39-194 +/- 7 ms, P < .0001), and a decrease in atrial FS (12 +/- 3% to 0 +/- 2%, P < .05) occurred. AF duration increased progressively and became persistent in 2 animals. VERP did not change significantly. Upon restoration of sinus rhythm, values returned to baseline within 48 hours. CONCLUSIONS AND CLINICAL IMPORTANCE: Atrial electrical and contractile remodeling appears rapidly. After 7 days of AF, reverse remodeling occurred within 2 days. These observations suggest that early conversion of AF might be beneficial for success rate and early return to training.
D De Clercq; G van Loon; R Tavernier; L Duchateau; Piet Deprez
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of veterinary internal medicine / American College of Veterinary Internal Medicine     Volume:  22     ISSN:  0891-6640     ISO Abbreviation:  J. Vet. Intern. Med.     Publication Date:    2008 Nov-Dec
Date Detail:
Created Date:  2008-11-12     Completed Date:  2008-12-19     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8708660     Medline TA:  J Vet Intern Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1353-9     Citation Subset:  IM    
Department of Large Animal Internal Medicine, Ghent University, Belgium.
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MeSH Terms
Atrial Fibrillation / pathology,  veterinary*
Cardiac Pacing, Artificial / adverse effects,  veterinary*
Horse Diseases*
Myocardial Contraction / physiology*
Time Factors
Ventricular Remodeling / physiology*

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