不应期离散与心肌电不稳定性关系的计算机模拟研究

The relation between dispersion of refractoriness and cardiac electrical instability in a computer model

目的 建立有限因素的计算机模拟心肌模型 ,使用计算机模拟心肌探讨不应期离散与心电不稳定性之间的关系。方法 在 PC机上 ,采用 Visual Basic编写应用程序 ,建立模拟心肌模型 ,模拟心肌由 2 5× 2 5个单元组成 ,各单元可以传导兴奋和恢复兴奋 ,在兴奋性没有完全恢复时 ,传导缓慢。根据电偶极子的原理 ,建立模拟心电图。采用颤动阈值 (fibrillation threshold,FT)作为评价心电不稳定性的指标。改变不应期的持续时间和离散程度 ,测定心动周期 (CL )从 10 0 TS开始到 2 0 TS,以 10 TS步长递减时的各个 CL 的颤动阈值 ,以及模拟心肌心电图的 QT间期。结果 不应期离散程度越大 ,FT值越低 ,出现自发性颤动的最短心动周期越长。不同原因的 QT间期延长 ,颤动阈值并不总是降低。结论 单纯不应期离散就可以导致折返性心律失常。不同原因的

Objective To investigate the relation between the dispersion of refractoriness and electrical instability of the simulated myocardium in a computer model.Methods A model was contrived with a personal computer with Visual Basic 5.0.The model was consisted of 25×25 units and simulated the propagation,recovery of excitability,and slow propagation during incomplete recovery.According to the electric dipole theory,simulated ECG was recorded.Fibrillation threshold(FT) was used for quantifying the cardiac electrical instability.FT's at different degrees of dispersion of refractory periods and QT intervals in simulating ECG at all cycle length from 100TS to 20TS in 10TS decrement were measured.Result The dispersion of refractoriness was well related to the decreased FT.The prolongation of QT interval with different causes did not coincide with that of the FT.Conclusion Dispersion of refractoriness is a sufficient condition to initiate reentrant dysrhhythmias.QT interval prolongation with different causes did not always mean lower myocardium vulnerability.