Department of Physics, Centre for Condensed Matter Theory, Indian Institute of Science, Bangalore, India.
PLoS One. 2011 Apr 5;6(4):e18052. doi: 10.1371/journal.pone.0018052.
Cardiac arrhythmias, such as ventricular tachycardia (VT) and ventricular fibrillation (VF), are among the leading causes of death in the industrialized world. These are associated with the formation of spiral and scroll waves of electrical activation in cardiac tissue; single spiral and scroll waves are believed to be associated with VT whereas their turbulent analogs are associated with VF. Thus, the study of these waves is an important biophysical problem. We present a systematic study of the combined effects of muscle-fiber rotation and inhomogeneities on scroll-wave dynamics in the TNNP (ten Tusscher Noble Noble Panfilov) model for human cardiac tissue. In particular, we use the three-dimensional TNNP model with fiber rotation and consider both conduction and ionic inhomogeneities. We find that, in addition to displaying a sensitive dependence on the positions, sizes, and types of inhomogeneities, scroll-wave dynamics also depends delicately upon the degree of fiber rotation. We find that the tendency of scroll waves to anchor to cylindrical conduction inhomogeneities increases with the radius of the inhomogeneity. Furthermore, the filament of the scroll wave can exhibit drift or meandering, transmural bending, twisting, and break-up. If the scroll-wave filament exhibits weak meandering, then there is a fine balance between the anchoring of this wave at the inhomogeneity and a disruption of wave-pinning by fiber rotation. If this filament displays strong meandering, then again the anchoring is suppressed by fiber rotation; also, the scroll wave can be eliminated from most of the layers only to be regenerated by a seed wave. Ionic inhomogeneities can also lead to an anchoring of the scroll wave; scroll waves can now enter the region inside an ionic inhomogeneity and can display a coexistence of spatiotemporal chaos and quasi-periodic behavior in different parts of the simulation domain. We discuss the experimental implications of our study.
心律失常，如室性心动过速（VT）和心室颤动（VF），是工业化国家主要的死亡原因之一。这些心律失常与心脏组织中电激活的螺旋波和涡旋波的形成有关；单个螺旋波和涡旋波被认为与 VT 有关，而它们的湍流类似物与 VF 有关。因此，研究这些波是一个重要的生物物理问题。我们对心肌组织的 TNNP（Ten Tusscher Noble Noble Panfilov）模型中肌纤维旋转和非均质性对涡旋波动力学的综合影响进行了系统研究。特别是，我们使用带有纤维旋转的三维 TNNP 模型，并考虑了传导和离子非均质性。我们发现，除了对非均质性的位置、大小和类型显示出敏感的依赖性外，涡旋波动力学还对纤维旋转的程度非常敏感。我们发现，涡旋波倾向于锚定在圆柱形传导非均质性上的趋势随着非均质性半径的增加而增加。此外，涡旋波的丝可以表现出漂移或蜿蜒、穿壁弯曲、扭曲和断裂。如果涡旋波丝表现出微弱的蜿蜒，那么波在非均质性处的锚固和纤维旋转对波钉扎的破坏之间存在一个微妙的平衡。如果这条丝表现出强烈的蜿蜒，那么纤维旋转又会抑制波的锚固；此外，只有当种子波出现时，涡旋波才能从大部分层中消除，然后再生。离子非均质性也会导致涡旋波的锚固；现在，涡旋波可以进入离子非均质性内部区域，并在模拟域的不同部分显示时空混沌和准周期性行为的共存。我们讨论了我们研究的实验意义。
