心力衰竭家兔心室动作电位时程整复性变化对室性心律失常的影响

 目的：探讨压力负荷诱导的兔慢性心力衰竭(CHF)模型离体心室动作电位时程整复性(APDR)变化对室性心律失常(VA)的影响。方法：雄性新西兰大耳兔20只，随机分为对照(CTL)组和CHF组，每组10只。CHF模型制备采用经腹主动脉缩窄术，造模结束4周后行心脏超声检查评价造模结果。在整体心脏Langendorff灌流条件下行离体电生理研究，分别记录和测量心室不同位点的单相动作电位(MAP)及有效不应期(ERP)，并绘制APDR曲线；对2组心脏进行快速电刺激，观察室性心律失常（VA）的诱发。结果：与CTL组相比，CHF组心室相同部位90%单相动作电位时程(MAPD90)、ERP及APDR曲线最大斜率(Smax)均明显增大(均P<0.01)，且VA更容易诱发(均P<0.05)；此外，CHF组动物APDR曲线Smax的变异系数(COV-Smax)均较CTL组增大(均P<0.05)。结论：CHF时心室APDR曲线Smax及COV-Smax均增大，促进室性心律失常的发生。

Effects of action potential duration restitution on ventricular arrhythmia in chronic heart failure rabbit hearts

AIM: To determine the effects of action potential duration restitution (APDR) on ventricular arrhythmia (VA) in Langendorff-perfused chronic heart failure (CHF) rabbit hearts. METHODS:Twenty male New Zea-land rabbits were equally divided into 2 groups randomly: control (CTL) group and CHF group. CHF was induced by abdominal aortic banding for 14 d. The echocardiography was applied to assess the cardiac function and structural change in both groups 4 weeks after the end of modeling. In the whole Langendorff-perfused hearts, the monophasic action potential (MAP) and the effective refractory period (ERP) were recorded and measured in ventricular chamber, and the action potential duration (APD) curves were also constructed in both groups. The burst pacing was used to induce APD alternans and VA. RESULTS: Compared with the same sites of CTL group, the 90% of MAP duration (MAPD90), the ERP, the maximal slope (Smax) of APDR curves were increased in CHF group (all P<0.05). The VAs in CHF group were easier to be induced than those in CTL group (all P<0.05). The coefficients of variation of Smax (COV-Smax) of APDR curves in CHF group were greater than those in CTL group (all P<0.05).CONCLUSION: Both Smax and COV-Smax of APDR curves increase during CHF to facilitate the ventricular arrhythmia.