Department of Mathematics, Purdue University, West Lafayette, Indiana 47907, USA.
Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Chaos. 2020 Mar;30(3):033111. doi: 10.1063/1.5134447.
Acute myocardial ischemia is an imbalance between myocardial blood supply and demand, which is caused by the cessation of blood flow within the heart resulting from an obstruction in one of the major coronary arteries. A severe blockage may result in a region of nonperfused tissue known as ischemic core (IC). As a result, a border zone (BZ) between perfused and nonperfused regions is created due to differences in blood and oxygen supplies. Recent experimental findings reveal a complex "finger-like" geometry in BZ; however, its effect on arrhythmogenicity is not clear. Ephaptic coupling, which relies on the intercalated disk between cell ends, has been suggested to play an active role in mediating intercellular electrical communication when gap junctions are impaired. In this paper, we explored the interplay between ephaptic coupling and the geometry of BZ on action potential propagation across the ischemic region. Our study shows that ephaptic coupling can greatly suppress the occurrence of a conduction block, which points to its beneficial effect. The beneficial effect of ephaptic coupling is more evident in BZ with the "finger-like" geometry. In addition, the complex geometry of BZ, i.e., more frequent, deeper, and wider "fingers," promotes the conduction through the ischemic region. In contrast, the larger size of IC impedes the cardiac conduction across the ischemic region. Our results also show that ephaptic coupling promotes the impact of the complex geometry of BZ on signal propagation; however, it inhibits the impact of IC size.
急性心肌缺血是心肌血液供应与需求之间的失衡，是由于心脏内的一条主要冠状动脉阻塞导致血流停止引起的。严重的阻塞可能导致一个无灌注组织区域，称为缺血核心（IC）。因此，由于血液和氧气供应的差异，在灌注和未灌注区域之间形成了一个边界区（BZ）。最近的实验结果揭示了 BZ 中复杂的“指状”几何形状，但它对心律失常性的影响尚不清楚。缝隙连接依赖于细胞末端之间的闰盘，当缝隙连接受损时，已有人提出缝隙连接通过缝隙连接介导细胞间电通讯中发挥积极作用。在本文中，我们探讨了缝隙连接和 BZ 几何形状对缺血区动作电位传播的相互作用。我们的研究表明，缝隙连接可以极大地抑制传导阻滞的发生，这表明其有益的作用。在具有“指状”几何形状的 BZ 中，缝隙连接的有益作用更为明显。此外，BZ 的复杂几何形状，即更频繁、更深、更宽的“手指”，促进了通过缺血区的传导。相比之下，IC 较大的尺寸会阻碍心脏在缺血区的传导。我们的结果还表明，缝隙连接促进了 BZ 复杂几何形状对信号传播的影响，但抑制了 IC 尺寸的影响。
