超高静磁场引起心电图T波变化的电生理学初步仿真研究

Electrophysiological simulation study of ECG T,wave alternation caused by ultrahigh static magnetic fields

目的初步仿真研究超高强度静磁场中的心电图T波幅度的改变机制。方法基于磁流体动力学模型,应用有限差分方法进行数值求解,通过改变磁场强度得到对应主动脉血流率;基于离子通道心室肌细胞模型,通过改变与ATP浓度相关的L型钙通道渗透率来仿真不同程度的心肌缺血情况。结果在超高静磁场中,人体主动脉的血流率减少可超过10%,可能会导致一定程度上的急性心肌缺血症;在不同心肌缺血情况下,心肌动作电位平台期受抑制,动作电位持续时间缩短,而透壁特异性增强,动态电生理力学心脏模型仿真得到心电图T波有较大改变。结论超高静磁场下主动脉血流率减少导致的心肌缺血会引起心电图T波幅度的明显增长,可能是超高静磁场对心电图T波影响的重要因素之一。

Objective To investigate the mechanisms of alternation in T-wave of ECG under ultrahigh static magnetic field （SMF）. Methods Based on magneto-hydrodynamics model and by changing the intensity of SMF, the volume flow rate of aorta was calculated by means of finite element method. Based on ionic-channel model of the cardiac ventricular cell, different degree of anoxia was simulated by changing the permeability of ATP-dependence of L-type calcium channel. Results Ultrahigh SMF could induce more than 10% reduction in volume flow rate of the blood in human aorta, which may induce anoxia condition of acute ischemia. The cardiac action potential plateau was suppressed and thus the action potential duration shortened, which result in enhanced transmural heterogeneity. ECG-T wave alternation were found in simulated dynamic electrophysiological heart model. Conclusion Under ultrahigh SMF, the reduction of the volume flow rate of the blood in aorta may induce acute ischemia and thus significant increase in the ECG T-wave amplitude, which may be an important of influ- encing factor of ultrahigh SMF on ECG T-wave.