The self-organized dynamics of vortex-like rotating waves, which are also known as scroll waves, are the basis of the formation of complex spatiotemporal patterns in many excitable chemical and biological systems. In the heart, filament-like phase singularities that are associated with three-dimensional scroll waves are considered to be the organizing centres of life-threatening cardiac arrhythmias. The mechanisms that underlie the onset, maintenance and control of electromechanical turbulence in the heart are inherently three-dimensional phenomena. However, it has not previously been possible to visualize the three-dimensional spatiotemporal dynamics of scroll waves inside cardiac tissues. Here we show that three-dimensional mechanical scroll waves and filament-like phase singularities can be observed deep inside the contracting heart wall using high-resolution four-dimensional ultrasound-based strain imaging. We found that mechanical phase singularities co-exist with electrical phase singularities during cardiac fibrillation. We investigated the dynamics of electrical and mechanical phase singularities by simultaneously measuring the membrane potential, intracellular calcium concentration and mechanical contractions of the heart. We show that cardiac fibrillation can be characterized using the three-dimensional spatiotemporal dynamics of mechanical phase singularities, which arise inside the fibrillating contracting ventricular wall. We demonstrate that electrical and mechanical phase singularities show complex interactions and we characterize their dynamics in terms of trajectories, topological charge and lifetime. We anticipate that our findings will provide novel perspectives for non-invasive diagnostic imaging and therapeutic applications.

中文翻译：

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心脏颤动期间的机电涡流丝

涡旋状旋转波（也称为涡旋波）的自组织动力学是许多可兴奋的化学和生物系统中复杂时空模式形成的基础。在心脏中，与三维滚动波相关的丝状相位奇点被认为是危及生命的心律失常的组织中心。心脏机电湍流的发生、维持和控制背后的机制本质上是三维现象。然而，以前无法可视化心脏组织内滚动波的三维时空动态。在这里，我们展示了使用高分辨率四维基于超声的应变成像可以在收缩的心壁内部深处观察到三维机械滚动波和丝状相位奇点。我们发现在心脏颤动期间机械相位奇点与电相位奇点共存。我们通过同时测量心脏的膜电位、细胞内钙浓度和机械收缩来研究电和机械相位奇点的动力学。我们表明可以使用机械相位奇点的三维时空动力学表征心脏纤颤，机械相位奇点出现在颤动收缩的心室壁内。我们证明了电气和机械相奇点表现出复杂的相互作用，并且我们根据轨迹、拓扑电荷和寿命来表征它们的动力学。我们预计我们的发现将为非侵入性诊断成像和治疗应用提供新的视角。