VENTRICULAR FIBRILLATION, MAPPING AND MODELING

描述（改编自申请人的摘要）：申请人的 总体目标将是阐明心室肌的机制， 使用高分辨率（500个电极） 地图绘制和计算机模拟。 重点将放在全球，而不是 而不是细胞机制。 待检验的假设是：1。 折返性 转子在Wigger的第二阶段VF期间存在，并负责 维持VF。 2. 转子的产生和维护取决于 心肌纤维定向及浦肯野纤维的影响 网络 3.需要临界质量来维持VF，因为 凹入转子的寿命有限。 Purkinje的作用 网络将通过执行实验进行评估， 用卢戈溶液消融浦肯野神经网 纤维取向 将通过组织病理学检查确定。 计算机 模拟研究将基于三维模型， 使用（改良的）FitzHugh-Nagumo系统的心肌激活 方程 现有的，详细的有限元模型的 犬心脏的结构将被用来代表几何形状 结构（即纤维取向）。 模型参数为 通过在二维中拟合模拟激活模式获得， 测量正常和折返模式的三维模型 在犬心脏的小区域中映射。 模型将是 外推以模拟整个心脏中的全局激活，并使用 研究心脏大小对VF的影响， 质量”假设与转子数量的关系。 该模型 也可用于研究纤维取向和浦肯野纤维的作用。 转子形成和维护的网络。

DESCRIPTION (adapted from the applicant's abstract): The applicant's overall objective would be to elucidate the mechanisms of ventricular fibrillation (VF) using a combination of high resolution (500-electrode) mapping and computer simulations. The focus would be on global rather than cellular mechanisms. Hypotheses to be tested are: 1. Reentrant rotors are present during Wigger's stage II VF and are responsible for maintaining VF. 2. The generation and maintenance of rotors depend on myocardial fiber orientation and the influence of the Purkinje fiber network. 3. A critical mass is needed to sustain VF because of the limited life span of the reentrant rotors. The role of the Purkinje network would be evaluated by performing experiments with and without the Purkinje network ablated using Lugol's solution. Fiber orientation would be determined by histopathological examination. The computer simulation studies would be based on a three-dimensional model of myocardial activation using the (modified) FitzHugh-Nagumo system of equations. An existing, detailed finite-element model of the architecture of the canine heart would be used to represent the geometry and structure (i.e. fiber orientation). Model parameters would be obtained by fitting simulated activation patterns in two-dimensional and three-dimensional models to measured normal and reentrant patterns mapped in small regions of the canine heart. The model would be extrapolated to simulate global activation in the whole heart and used to study the effect of heart size on VF and to examine the "critical mass" hypothesis in relation to the number of rotors. The model would also be used to study the role of fiber orientation and of the Purkinje network on rotor formation and maintenance.