PREVALENCE OF ATRIAL FIBRILLATION CAUSED BY ACUTE ATRIAL DILATION DECREASED IN RAT DISEASEDHEART

摘要

Although acute atrial dilation has shown to facilitate the induction of atrial fibrillation (AF) in normal heart, little is known whether the prevalence of AF due to acute atrial dilation also increases in diseased heart. To clarify this, we compared inducibility of AF in rats without and with chronic atrial dilation. Methods: Eight weeks after abdominal aortocaval shunt and aortic constriction (group-A) or sham operation (group-B), hearts were perfused in Langendorff s manner. Right atrial pressure was increased to 10cm H2O by the height of the reservoir. Inducibility of AF was evaluated by 5 times burst pacing from right atrium, and mean cycle length of AF (CL) and right atrial effective refractory period (AERP) were also measured. Moreover, histological examinations of the right atrium were performed. Results: The inducibility of AF in group-A was lower than in group-B (A, 12t6% vs B 5O+-5%, p<0.05). CL and AERP in group-A were longer than in group-B. Histology revealed interstitial atrial fibrosis in group-A. Conclusion: The prevalence of AF caused by acute atrial dilation decreased in diseased heart, suggesting that electrophysiological and histological remodeling may play a crucial role at least in compensated state for the prevention of AF due to acute atrial dilation.