机械-电反馈对心衰心室肌电重构的影响

目的:观察心衰时心室前后负荷改变基础上快速心室刺激导致的心室肌电生理特性的改变,探讨机械-电反馈对心室肌电重构的影响。方法:138只兔随机分为心衰组和正常组。在兔心外膜四个部位分别以220、240、260次/分为刺激频率测定单向动作电位时程(MAPD)及心室有效不应期(VERP)。并分别增加前后负荷后,再作上述测定。然后置电极于右房,以260次/分频率快速刺激30 min,重复测定。并以S1S2S3刺激方法诱发室颤,记录诱发率和持续时间。结果:心衰组在增加前或后负荷快速刺激后,均表现为MAPD90、VERP延长,四个部位之间差异明显。正常组虽有延长趋势,但统计学差异不明显。心衰组的室颤诱发率及平均持续时间显著高于正常各组,增加前、后负荷后更明显。结论:心衰时增加前、后负荷并快速心室刺激导致心室肌电重构的不均匀性明显增加,可能是心衰室性心律失常易于发生的原因。

The Influence of Mechano-electric Feedback on Ventricular Electrical Remodeling in Rabbits with Congestive Heart Failure

Objective:To explore the influence of mechano-electrical feedback on ventricular eletrical remodeling by rapid ventricular activation accompanied increasing acute preload and afterload in rabbits with congestive heart failure(CHF).Methods:One hundred and thirty-eight rabbits were divided into CHF and control groups.Four electrodes were placed at epicardium of rabbit respectively to measure MAPD90 and VERP during ventricular pacing at frequency of 220,240,260 per minute separately after increasing preload or afterload.Rapid atrial pacing(RAP) was given for 30 minutes.The MAPD90 and VERP were measured again.Then ventricular fibrillation(VF) was induced by S1S2S3 program stimulation,and rate and duration of induced ventricular fibrillation,and occurrence of early afterdepolarizations were recorded.Results:In CHF group,MAPD90 and VERP were significantly prolonged comparing to normal control after RAP.The extent of prolongation of MAPD90 and VERP were not significantly increased in group CHF after increasing preload or afterload comparing to those without load,but the regional variance was increased in CHF group after increasing preload or afterload comparing to those without load.The rate of induced ventricular fibrillation and afterdepolarization were higher in CHF group than in control group,especially after increasing preload or afterload.Conclusion:The findings suggest that increasing preload or afterload could increase regional variance of eletrophysiologic properties of myocardium to predispose to ventricular arrhythmia.