CHAOS AND CARDIAC ARRHYTHMIAS

可激发介质中的多重循环波前 计算机模拟是时空混沌的一个例子。 他们的 与实验记录的激活模式非常相似， 心房或心室纤维性颤动提示纤维性颤动也可能 一种时空混沌的形式，并提出了一种可能性， 最近开发的混沌控制策略可以应用于 纤维性颤动 我们之前已经证明，基于 混沌控制理论可以成功地对一个混沌心室进行调节， 哇巴因诱发家兔离体心室心动过速 主要 该项目的目标是确定类似的战略是否可以 用于治疗心室纤颤 我们改装了货车 Capelle & Durrer二维传播计算机模型 激发晶格，并已表明，多个循环波前 （螺旋波）可以诱导模拟纤颤。 本地站点 录音显示了混乱行为的明确证据，并展示了 动力学特征（不动点和稳定与不稳定流形） 有必要应用OGY混沌控制方法，我们成功地 应用于哇巴因引起的混乱性心律失常 模型紧密 模拟了内循环重入波前的行为 项目2中描述的体外犬心外膜切片制备， 也显示了当地录音现场混乱的证据。 标准 检测晶格中各个元素处的时空混沌 （相当于可以从当地 心内电图）将在货车Capelle & Durrer 模型，并使用此信息开发基于扰动策略 混沌控制理论（类似于在一个或多个站点上踱步， 晶格），以确定是否可以局部和全局混沌控制， 办妥了一批 计算机模拟的结果将被直接验证 实验使用体外犬心外膜切片制备 如果成功的话，就能适应体内移植的犬心脏。 该项目的第二个目标是进一步了解和改善 我们以前成功地实现了混沌控制起搏算法， 哇巴因诱发家兔室性心动过速 室间隔，一种空间复杂性较低的混沌心脏 心律不齐 使用细胞外高分辨率激活标测 电极，将绘制哇巴因诱导的心律失常以评估其 机制和空间属性，并深入了解机制 从而证明了混沌控制定步算法的有效性。 改进 我们目前的混沌控制算法将进一步发展， 在间隔准备中测试。 这些对混乱的改善 哇巴因诱发心律失常的控制起搏算法将 对于为纤维性颤动设计的混沌控制起搏算法至关重要。 最终，我们的目标是开发一种智能起搏策略， 基于混沌控制理论， 显著降低除颤阈值。

Multiple circulating wavefronts in an excitable medium produced by computer simulations are an example of spatio-temporal chaos. Their close similarity to experimentally-recorded activation patterns during atrial or ventricular fibrillation suggest that fibrillation may also be a form of spatio-temporal chaos, and raises the possibility that recently-developed chaos control strategies can be applied to fibrillation. We have previously shown that a pacing algorithm based on chaos control theory could successfully regularize a chaotic ventricular tachycardia induced by ouabain in isolated rabbit ventricle. The major objective of this project is to determine whether a similar strategy can be developed for ventricular fibrillation. We have modified the van Capelle & Durrer computer model of propagation in a two-dimensional excitable lattice, and have shown that multiple circulating wavefronts (spiral waves) simulating fibrillation can be induced. Local site recordings show clear evidence of chaotic behavior, and exhibit the dynamic features (fixed point and stable and unstable manifolds) necessary to apply the OGY chaos control method, which we successfully applied to the chaotic ouabain-induced arrhythmia. The model closely simulates the behavior of circulating reentrant wavefronts in the in vitro canine epicardial slice preparation described in Project 2, which also shows evidence of chaos at local recording sites. Criteria for detecting spatio-temporal chaos at individual elements in the lattice (equivalent to the information that could be obtained from a local intracardiac electrogram) will be developed in the van Capelle & Durrer model, and this information used develop a perturbation strategy based on chaos control theory (analogous to pacing at a one or more sites in the lattice) to determine whether local and global chaos control can be achieved. The results of computer simulations will be directly validated experimentally using the in vitro canine epicardial slice preparation and, if successful, adapted to the in vivo fibrillating canine heart. A second objective of the project is to further understand and improve the chaos control pacing algorithm which we have previously successfully applied to ouabain-induced ventricular tachycardia in the rabbit interventricular septum, a less spatially complex chaotic cardiac arrhythmia. Using high resolution activation mapping with extracellular electrodes, the ouabain-induced arrhythmia will be mapped to evaluate its mechanism and spatial properties, and to gain insight into the mechanism by which the chaos control pacing algorithm is effective. Improvements to our current chaos control algorithm will be further developed and tested in the septal preparation. These improvements to the chaos control pacing algorithm in the ouabain-induced arrhythmia will be essential for chaos control pacing algorithms designed for fibrillation. Ultimately, the goal is to develop an intelligent pacing strategy based on chaos control theory which will either terminate fibrillation or significantly decrease the defibrillation threshold.