The Time Course Of Electrical Remodeling, Structural Remodeling, Neural Remodeling And Endothelin-1Level In Atrial Fibrillation

Objective: The consistency between electrical remodeling, structural remodeling,neural remodeling and endothelin-1level in atrial fibrillation（AF） has not been reported.The present study aimed to investigate the time course of atrial electrical remodeling,structure remodeling and neural remodeling as well as endothelin-1（ET-1） in AF rabbitmodels induced by rapid atrial pacing, and to explore the possible values of ET-1inpredicting the initiation and development of AF, so as to guide the treatment for AF.Method: Forty Adult New Zealand rabbits, rapid atrial pacing （600bpm） was performedto made paroxysmal AF models. The experimental animals were randomely divided intofive groups by pacing time,0h group （P₀）,4h group （P₄）,8h group （P₈）,12hgroup(P₁₂),24h group（P24）,（n=8）. The AF induction rate, AERP, rate adapation of AERP,ventricular ejection fraction （EF）,heart rate variability （HRV）,plasma ET-1, FPdur andthe field potential morphous of atrial tissues, anti-growth-associated protein-43（GAP-43）,anti-cholineacetyltransfer-ase （ChAT）, anti-tyrosine hydroxylase （TH） andanti-endothelin-1（ET-1） antibodies in atrial tissues were measured after pacing0h,4h,8h,12h,24h. Results:The success rate of rapid right atrial pacing24h in rabbits forbuilding AF model was95%,25%rabbit normal heart can be induced to AF. Theinduction rate at pacing0h,4h,8h,12h,24h were25%,37.5%,65%,75%,85%,respectively. After pacing8h, AERP was significantly shortened,the rate adaptive of AERP was significantly decreased, the Fpdur of atrial tissues wassignificantly prolongerd. The shortening of general AERP was inhomogeneous,but thedispersion of Fpdur was increased.The EF was significantly increased after AF8h andatrial pathological changes started at AF24h. The mean R-R internal was significantlydecreased at pacing4h, but increased to the maximum at pacing24h. The LF and HFwas significantly increased at pacing12h and24h,respectively. The LF/HF wasgradually decreased and significantly decreased at pacing24h. After pacing24h, thedensity of GAP43-positive,ChAT-positive and TH-positive in the left and right atrium were higher than the density in0h group; Furthermore, after pacig24h, the left atriumhad significantly higher nerve density of GAP43-positive and ChAT-positive than theright atrium. Plasma ET-1was significantly increased after pacing12h and rise to themaximum after24h. There was no significant changes of ET-1in atrial tissues afterpacing, it was significantly increased until pacing24h. Conclusion: The atrial electricalremodeling, structural remodeling, neural remodeling occurred uniformly at rapid atrialpacing8h. The plasma ET-1level significantly increased after AF persist for12h. Theplasma ET-1level may be used to presume the duration time of AF. The increased atrialtissue ET-1level after AF persisting for24h may be the trigger factors of “AF begetsAF”.