Roth Bradley J, Langrill Beaudoin Deborah
Department of Physics, Oakland University, Rochester, Michigan 48309, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2003 May;67(5 Pt 1):051925. doi: 10.1103/PhysRevE.67.051925. Epub 2003 May 27.
The mechanism by which an applied electric field stimulates cardiac tissue far from the stimulating electrodes is not wholly understood. One possible mechanism relates the curving cardiac fibers to the induced membrane currents and transmembrane potentials. However, we lack a qualitative understanding of where these areas of polarization will occur when an electric field is applied to a sheet of cardiac tissue with curving fibers. In our study, we derive an analytical model for the transmembrane potential, dependent on the gradient of the fiber angle theta, for a two-dimensional passive sheet of cardiac tissue exhibiting various fiber geometries. Unequal anisotropy ratios are crucial for our results. We compare the results from our analytical solution to a numerical calculation using the full bidomain model. The results of our comparison are qualitatively consistent, albeit numerically different. We believe that our analytical approximation provides a reliable prediction of the polarization associated with an electric field applied to cardiac tissue with any fiber geometry and a qualitative understanding of the mechanisms behind the virtual electrode polarization.
外加电场刺激远离刺激电极的心脏组织的机制尚未完全明确。一种可能的机制是将弯曲的心脏纤维与诱导的膜电流和跨膜电位联系起来。然而，当电场施加于具有弯曲纤维的心脏组织片时，我们对这些极化区域将出现在何处缺乏定性的认识。在我们的研究中，我们针对呈现各种纤维几何形状的二维被动心脏组织片，推导了一个依赖于纤维角度θ梯度的跨膜电位分析模型。不等的各向异性比率对我们的结果至关重要。我们将解析解的结果与使用完整双域模型的数值计算结果进行比较。尽管数值不同，但我们的比较结果在定性上是一致的。我们认为，我们的解析近似为与施加于任何纤维几何形状的心脏组织的电场相关的极化提供了可靠的预测，并对虚拟电极极化背后的机制有了定性的理解。
