低钾对长QT综合征心室肌组织易损窗的影响——计算机仿真研究

The effect of hypokalemia on the vulnerable window in LQTS——A computer simulation study

目的探讨细胞外低钾时长QT综合征(LQTS)室性心律失常发生率增高的原因。方法采用计算机仿真方法,分别观察了不同程度低钾对LR91一维非均质心室肌模型的时间、空间及电压易损窗的影响。实验分为正常组和LQTS组。以500,1000和2000ms的刺激周长对一维模型施加基础刺激S1(-70μA/μF、1.5ms)10次后,测量动作电位时程及传导速度。每10次S1后施加期前刺激S2,S1S2间期以1ms的步长递减测量易损窗。结果在不同刺激频率条件下,随[K+]O的减低,正常组和LQTS模型组的时间、电压、空间易损窗逐渐增大,且LQTS模型组易损窗均大于正常组。易损窗变化表现有频率依赖性。结论低钾增加了单向传导阻滞的发生机率,是导致室性心律失常发生率增高的重要原因。

Objective To analyse the reason why hypokalemia could increase the incidence of ventricular arrhythmia in Long QT syndrome（LQTS）. Methods We observed the effect of hypokalemia on time, potential and space vulnerable window （VW） in the LR91 1-dimensional heterogeneous cardiac ventricular tissue model, respectively. The samples were divided into two groups, control and LQTS groups. The action potential duration and conduction velocity were elicited after giving basic stimulus S1 （ - 70 μA/μF, 1.5 ms） 10 times with basic cycle length 500,1 000 and 2 000 ms. The three types of VWs were tested by giving premature stimulus S2 and decreasing S1S2 interval at the decrement of 1 ms. Results Hypokalemia enlarged three types of VWs in both groups, especially in the LQTS group, and the VWs were getting larger as pacing rate was decreased. Conclusions Under hypokalemia, it is easy to cause unidirectional conduction block and lead to the initiation of cardiac reentry.