慢性心力衰竭兔离体心室电整复性变化对室性心律失常的影响

Action potential duration restitution and the potential association with ventricular arrhythmia in Langendorff-perfused chronic heart failure rabbit hearts

目的探讨异丙肾上腺素诱导的兔慢性心力衰竭（CHF）模型离体心室动作电位整复性（APDR）变化对室性心律失常的影响。方法雄性新西兰大耳兔30只，随机分为对照组和CHF组，每组15只。采用经耳缘静脉注射异丙肾上腺素（300μg·kg^-1·d^-1。）法建立兔CHF模型，建立模型结束4周后行心脏超声检查评价其结果。在整体心脏Langendorff灌流条件下行离体电生理研究，分别记录和测量左心室前壁基底部、左心室前游离壁、左心室前壁心尖部、左心室后壁基底部、左心室后游离壁和左心室后壁心尖部的单相动作电位及有效不应期，并绘制APDR曲线。对上述6个部位行程控增频刺激和快速电刺激，分别用以观察动作电位时程电交替及室性心律失常的诱发。结果与对照组比较，CHF组心室相同部位90％单相动作电位时程、有效不应期及APDR曲线最大斜率（Smax）均明显大（P均〈0．01）、动作电位时程电交替提前（P〈0．05）、更容易诱发室性心律失常（P〈0．05）。此外，CHF组兔整个左心室的90％单相动作电位时程离散度、有效不应期离散度及APDR曲线Smax离散度均大于对照组（P均〈0．05）。结论心室动作电位时程电交替可预测CHF兔室性心律失常的发生。CHF兔心室APDR曲线Smax及Smax离散度均增大，促进了室性心律失常的发生。

Objective To observe the action potential duration restitution （APDR） change and potential association with ventricular arrhythmia （VA） in Langendorff-perfused chronic heart failure rabbit hearts. Methods Male rabbits were randomly divided into two groups： control （ CTL, n = 15 ） group and chronic heart failure （CHF, n = 15 ） group. CHF was induced by injecting isoproterenol （300 μg·kg^-1·d^-1） for 14 days. Four weeks later, cardiac function and structure change of both groups were assessed by echocardiography. In the whole Langendorff-perfused hearts, the monophasic action potential （MAP） and the effective refractory period （ERP） were recorded from left anterior basal ventricle, left anterior free wall, left anterior apex and left posterior basal ventricle, left posterior free wall and left posterior apex, the APD curves were also constructed in both groups; at the six sites of every isolated heart, the programmed electrical stimulation and burst pacing were used to induce action potential duration （APD） alternans and VA, respectively. Results Left ventricular ejection was reduced and end-dimension was enlarged in rabbits of CHF group. Compared with the same sites of CTL group, the 90% of MAP duration （ MAPDg0 ）, the ERP, the max slope （ Smax ） of APDR curves, the pacing cycle length of inducing the APD alteruans and the VAs were significantly increased （ all P 〈 0. 05 ） in CHF group ; the spatial dispersions of MAPDgo, ERP and Smax of APDR curves in CHF group were also greater than in CTL group （all P 〈 O. 05）. Conclusion The ventricular APD alternans might be linked with occurrence of the VA in CHF rabbits. Increase of the Smax from APDR curves and the spatial dispersions of S in this CHF model might facilitate the development of ventficulararrhythmia.