Nonlinear Physics and Mathematical Modeling Laboratory, University Campus Bio-Medico of Rome, Via A. del Portillo 21, I-00128 Rome, Italy.
Europace. 2014 Mar;16(3):424-34. doi: 10.1093/europace/euu031.
Hypothermia is well known to be pro-arrhythmic, yet it has beneficial effects as a resuscitation therapy and valuable during intracardiac surgeries. Therefore, we aim to study the mechanisms that induce fibrillation during hypothermia. A better understanding of the complex spatiotemporal dynamics of heart tissue as a function of temperature will be useful in managing the benefits and risks of hypothermia.
We perform two-dimensional numerical simulations by using a minimal model of cardiac action potential propagation fine-tuned on experimental measurements. The model includes thermal factors acting on the ionic currents and the gating variables to correctly reproduce experimentally recorded restitution curves at different temperatures. Simulations are implemented using WebGL, which allows long simulations to be performed as they run close to real time. We describe (i) why fibrillation is easier to induce at low temperatures, (ii) that there is a minimum size required for fibrillation that depends on temperature, (iii) why the frequency of fibrillation decreases with decreasing temperature, and (iv) that regional cooling may be an anti-arrhythmic therapy for small tissue sizes however it may be pro-arrhythmic for large tissue sizes.
Using a mathematical cardiac cell model, we are able to reproduce experimental observations, quantitative experimental results, and discuss possible mechanisms and implications of electrophysiological changes during hypothermia.
众所周知，低温会导致心律失常，但它作为一种复苏治疗方法具有有益的效果，并且在心脏内手术中也很有价值。因此，我们旨在研究导致低温时发生纤维性颤动的机制。更好地理解心脏组织的复杂时空动力学随温度的变化，将有助于管理低温的益处和风险。
我们使用经过实验测量精细调整的心脏动作电位传播最小模型进行二维数值模拟。该模型包括作用于离子电流和门控变量的热因素，以正确再现不同温度下的实验记录的恢复曲线。模拟使用 WebGL 实现，这允许长时间的模拟接近实时运行。我们描述了（i）为什么在低温下更容易诱发纤维性颤动，（ii）纤维性颤动所需的最小尺寸取决于温度，（iii）为什么纤维性颤动的频率随温度降低而降低，以及（iv）局部冷却可能是针对小组织尺寸的抗心律失常疗法，但对于大组织尺寸可能是致心律失常的。
使用数学心脏细胞模型，我们能够再现实验观察、定量实验结果，并讨论低温期间电生理变化的可能机制和影响。
