Ventricular fibrillation (VF) is a life-threatening electromechanical dysfunction of the heart associated with complex spatiotemporal dynamics of electrical excitation and mechanical contraction of the heart muscle. It has been hypothesized that VF is driven by three-dimensional rotating electrical scroll waves, which can be characterized by filamentlike electrical phase singularities or vortex filaments, but visualizing their dynamics has been a long-standing challenge. Recently, it was shown that rotating excitation waves during VF are associated with rotating waves of mechanical deformation. Three-dimensional mechanical scroll waves and mechanical filaments describing their rotational core regions were observed in the ventricles by using high-resolution ultrasound. The findings suggest that the spatiotemporal organization of cardiac fibrillation may be assessed from waves of mechanical deformation. However, the complex relationship between excitation and mechanical waves during VF is currently not understood. Here, we study the fundamental nature of mechanical phase singularities, their spatiotemporal organization, and their relation with electrical phase singularities. We demonstrate the existence of two fundamental types of mechanical phase singularities: “paired singularities,” which are colocalized with electrical phase singularities, and “unpaired singularities,” which can form independently. We show that the unpaired singularities emerge due to the anisotropy of the active force field, generated by fiber anisotropy in cardiac tissue, and the nonlocality of elastic interactions, which jointly induce strong spatiotemporal inhomogeneities in the strain fields. The inhomogeneities lead to the breakup of deformation waves and create mechanical phase singularities, even in the absence of electrical singularities, which are typically associated with excitation wave break. We exploit these insights to develop an approach to discriminate paired and unpaired mechanical phase singularities, which could potentially be used to locate electrical rotor cores from a mechanical measurement. Our findings provide a fundamental understanding of the complex spatiotemporal organization of electromechanical waves in the heart and a theoretical basis for the analysis of high-resolution ultrasound data for the three-dimensional mapping of heart rhythm disorders.

中文翻译：

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高频心律失常机电相位奇点的时空组织

心室颤动 (VF) 是一种危及生命的心脏机电功能障碍，与心肌电激发和机械收缩的复杂时空动力学有关。据推测，VF 是由 3D 旋转电涡旋波驱动的，其特征可以是丝状电相位奇点或涡旋丝，但可视化它们的动力学一直是一个长期的挑战。最近，研究表明，VF 期间的旋转激励波与机械变形的旋转波有关。通过使用高分辨率超声在心室中观察到描述其旋转核心区域的三维机械涡旋波和机械细丝。研究结果表明，心脏纤颤的时空组织可以通过机械变形波来评估。然而，目前尚不清楚 VF 期间激励和机械波之间的复杂关系。在这里，我们研究了机械相位奇点的基本性质、它们的时空组织以及它们与电相位奇点的关系。我们证明了两种基本类型的机械相位奇点的存在：与电相位奇点共定位的“成对奇点”和可以独立形成的“不成对奇点”。我们表明，由于心脏组织中纤维各向异性产生的主动力场的各向异性以及弹性相互作用的非定域性，会出现不成对的奇点，这共同在应变场中引起强烈的时空不均匀性。不均匀性会导致变形波的破裂并产生机械相位奇点，即使在没有电奇点的情况下也是如此，这通常与激发波断裂有关。我们利用这些见解开发了一种区分成对和不成对机械相位奇点的方法，该方法可能用于从机械测量中定位电转子芯。我们的研究结果提供了对心脏机电波复杂时空组织的基本理解，并为分析高分辨率超声数据用于心律失常的三维映射提供了理论基础。不均匀性会导致变形波的破裂并产生机械相位奇点，即使在没有电奇点的情况下也是如此，这通常与激发波断裂有关。我们利用这些见解开发了一种区分成对和不成对机械相位奇点的方法，该方法可能用于从机械测量中定位电转子芯。我们的研究结果提供了对心脏中机电波复杂时空组织的基本理解，并为分析高分辨率超声数据用于心律失常的三维映射提供了理论基础。不均匀性会导致变形波的破裂并产生机械相位奇点，即使在没有电奇点的情况下也是如此，这通常与激发波断裂有关。我们利用这些见解开发了一种区分成对和不成对机械相位奇点的方法，该方法可能用于从机械测量中定位电转子芯。我们的研究结果提供了对心脏中机电波复杂时空组织的基本理解，并为分析高分辨率超声数据用于心律失常的三维映射提供了理论基础。这通常与激发波中断有关。我们利用这些见解开发了一种区分成对和不成对机械相位奇点的方法，该方法可能用于从机械测量中定位电转子芯。我们的研究结果提供了对心脏中机电波复杂时空组织的基本理解，并为分析高分辨率超声数据用于心律失常的三维映射提供了理论基础。这通常与激发波中断有关。我们利用这些见解开发了一种区分成对和不成对机械相位奇点的方法，该方法可能用于从机械测量中定位电转子芯。我们的研究结果提供了对心脏中机电波复杂时空组织的基本理解，并为分析高分辨率超声数据用于心律失常的三维映射提供了理论基础。