心肌肥厚小鼠离体心脏心室的电生理特征

Electrophysiological property of ventricle in mouse isolated heart with cardiac hypertrophy

目的探讨心肌肥厚状态下小鼠离体心脏心室的电生理特征。方法取10～12周龄C57BL6小鼠30只,随机等分为手术组与对照组,手术组接受胸主动脉缩窄术;对照组只开胸,不行胸主动脉缩窄。4周后行心脏超声检查。取心脏后应用Langendorff行离体心脏灌流。检测心脏不同部位包括左室外膜、左室内膜以及右室的单相动作电位(MAP)及外膜双极电图的变化,于程控刺激(PES)(S1固定周长125 ms,S2从125 ms开始以-1 ms反扫)及Burst刺激(50 Hz持续2 s的串刺激)下观察室性快速心律失常诱发率,并应用PEFA(Paced electrogram fractionation analysis)分析方法绘制激动潜伏时间曲线并测量起始电图宽度,终末电图宽度以及电图比率。结果与对照组比较,手术组心脏体重比和左室体重比明显增大(P<0.05),心室间隔厚度与左室后壁厚度明显增厚(P<0.05)。QTc间期与内、外膜APD90亦明显延长(P<0.05),且内膜面心肌MAP延长更明显。在PES下S2激动潜伏时间、外膜双向电图时程(EGD)及EGD比率比手术组明显增大(P<0.05)。手术组室性心律失常诱发率在PES及Burst刺激下明显高于对照组,且持续时间更长。结论心肌肥厚状态下整体心室兴奋传导和复极化的延迟以及空间异质性是导致室性心律失常发生的潜在机制。

Objective To elucidate the electrophysiological property and arrhythmogenesis of ventricle in mouse isolated heart with cardiac hypertrophy. Method Thirty C57BL6 mice were randomly divided into two groups, one of which ac- cepted the aortic banding operation and other group accepted chest operation but didn＇t band aorta. Two groups were as- sessed by anatomy and echoeardiogram 4 weeks after operation. The Monophasic action potential （MAP） and bipolar elec- trogram （BEG） were detected in langendorff perfused heart, and the ventricular tachyarrhythmias were electrically induced by PES and burst stimuli. In addition, the paced eleetrogram fraetionation analysis （PEFA） was used to assess the sub- strate of arrhythmogenesis. Result Operated group showed larger values of HW/BW, LVW/BW, IVSD and LVPWD than control group （P〈0.05）. The inducibility of arrhythmias was markedly increased in operated group by PES （41.2%） and Burst stimuli （23.5%）. The QT interval and action potential duration （APD） were markedly prolonged in operated group （ P〈0.05 ） , and alerted with spaeial heterogeneity. The latency, EGD and EGD ratio were also increased in operated group （ P〈0.05 ） by PEFA. Conclusion Ventricular taehyarrhythmias were more intensive to PES than Burst stimuli in hypertrophic hearts, and the prolongation of conductive latency and repolarization as well as its spaeial heterogeneity possi- bly underlying to substrate of arrhythmogenesis during cardiac hypertrophy.