Effect Of Spironolactone On The Remodeling In Rapid Atrial Pacing In Rabbits

Objective In recent years, a large number of research show that the atrial remodelingplay an important role in atrial fibrillation occur and maintain,How to reversalatrial remodeling has become a new hot point in atrial fibrillation treatment. Manystudies suggest that Renin-Angiotensin-Aldosterone System(RAAS) involved in theformation and maintenance of atrial fibrillation mechanism, thus to further explore therole of the RAAS system in atrial remodeling and to search effecticve drugs to inhibitatrial remodeling has very important clinical significance. In this research we establishrapid atrial pacing in the rabbit model,to evaluate the effect of aldosterone receptorantagonist-spironolactone on atrial remodeling.Methods A cohort of30rabbits were randomly assigned into3groups: control group(n=10), rapid pacing group (n=10) and spironolactone group (n=10). Implantelectrode catheter in the right atrium through internal jugular vein.Then taking a rapidatrial pacing (800bpm).Atrial effective refractory period was measured at basic cyclelength of200ms and150ms at before pacing and1,2,4,6,8hours after pacing.And thento analyze the rate adaptation of AERP. The atrial myocardium were collected at8hoursafter pacing and were examined by eletron micriscopy.Results The AERP at each basic cycle lengths was significanty shortened in rapidpacing group when it compared with the control group after pacing8hours (P<0.05)，and the rate adaptation of AERP was lost.Electron microscopic studies of right atrialar appendage tissue demonstrated that the muscle ultrastructure have obvious changes,such as myocardial fibers arranging disorderly,mitochondrial swelling and organelleswere obviously reduced in rapid pacing group. The shortening of AERP was attenuateand the rate adapation was maintained in spironolactone group（P>0.05）.The change ofheart muscle ultrastructure not so obvious compared with the rapid pacing groupConclusions Rapid pacing can cause atrial electrical remodeling and structuralremodeling.Aldosterone receptor antagonist–spironolactone could inhibit electricalremodeling and release the atrial structure remodeling during rapid atrial pacingeffectively.This study indicates that spironolactone may influence atrial remodeling andlead us to the better therapeutic management of human in subjects with atrialfibrillation.