24h快速起搏右心房致心房肌电重构和结构重构的研究

Study on electrical,structural remodeling of atrium in an experimental rabbit models of pacing-induced atrial fibrillation

目的探讨兔24h快速心房起搏(rapid atrial pacing,RAP)对心房肌电重构(electrical remodeling,ER)和结构重构的影响。方法由新疆医科大学动物实验中心提供一级质量标准的成年新西兰大白兔24只,体质量2.5～3kg,雌雄不拘。随机分为两组:假手术组和模型组,每组各12只。假手术组兔仅植入起搏电极,不行高位右心房快速起搏刺激。模型组兔经颈内静脉将电极置入右心房。以600次/min行RAP,同时分析模型组在0、8、12、24h4个时间点的心房有效不应期(atrial effective refractory period,AERP),24hRAP后,迅速开胸取心脏,剪下右心房和左上肺静脉,经HE染色和Masson染色行组织学观察。结果假手术组在不同基础刺激周长作用下和时间点AERP无显著改变(P>0.05)。模型组在起搏P8、P12和P24后,与P0相比,AERP200明显缩短(P<0.05);与P0相比,AERP150在起搏P8、P12和P24后明显缩短(P<0.05)。假手术组心房肌的HE染色肌纤维呈纵行排列,横纹清楚;模型组肌纤维走行方向各异,间隙较大,横纹不清,胞浆空泡化,细胞肿胀。Masson染色结果显示,假手术组胶原纤维为蓝绿色,少量分布于肌纤维之间;模型组大量胶原纤维相互连接成网状,排列紊乱。结论心房颤动(AF)时心房电重构(ER)以AERP缩短为特点。AF后的右心房出现细胞肥大、纤维结缔组织增生等病理改变。

Objective To explore electrical, structural remodeling of atrium in an experimental rabbit rood els of pacing-induced atrial fibrillation. Methods Twenty four New Zealand white rabbits of either sex （weight 2.5 to 3.0 kg, n =24） were randomly divided into 2 groups, sham operated group （n =12） and model group （n =12）. Sham operated group was only implanted pacing electrode, but was not maked the high right atrium pacing stimulation. Model group was implanted pacing electrode in the right atrium via the internal jugular vein and paced in 600 bpm rapidly right atrium pacing （RAP）. All animals were esthe- tized with pentobarbital （30 mg/kg followed by 5 mg/kg/h, i. v. ）. AERP was measured by programmed electrical stimulation before pacing and from 0 to 24 hours after the onset of the pacing. The hearts were quickly removed, right atrial appendage（RAA） were sliced. RAA samples were collected, the structure of RAA was observed by HE staining, myocardial fibrosis was displayed by Masson stainin. Results The AERP was shortened and the rate adapation of AERP was lost through the pacing process compared with those before pacing （P 〈0.05）. Histological examination of RAA revealed remarkable myocardial hypertrophy, irregular array of cardiocyte and myocardium interstitial fibrosis. Conclusion After 24 h RAP, the AERP was shortened, myocardial hypertrophy, irregular array of cardiocyte and myocardium interstitial fibrosis in RAA, which is ready for the onset and maintenance of AF by rapid atrial pacing in rabbits.