EXPERIMENTAL AND NUMBERICAL ANALYSES OF DEFIBRILLATION

这项建议的目的是确定心肌分布， 除颤过程中的电流密度及其对除颤的影响 成功这项研究的一个假设是， 必须到达心肌内以实现除颤。一 第二个假设是该阈值电流密度不随 在自我平衡的条件下对特定物种的影响。 是否达到阈值心肌电流密度对于给定的 除颤尝试取决于电流分布 心肌这种分布是复杂的，由于不均匀性， 心脏容积导体和心肌传导性的各向异性， 此外，可以通过诸如电极尺寸和放置等因素来改变， 以及急性缺血和梗塞组织的存在。一个系统 将进行研究，以确定之间的定量关系 这些参数和心肌电流分布。长期 目的是优化除颤脉冲的递送， 根据临床条件。 由于实验和数值方法的局限性， 问题，本次调查将联合收割机结合这两种方法在一个互补的 时尚.将开发用于有限元的数字躯干模型 分析.这个模型最终将能够预测当前的 对于给定的一组经胸或 经心脏的状况与这项工作同时进行的将是 一个256通道数据采集系统的映射三分量 心外膜电流密度， 心肌和激活波阵面之前和之后， 脉搏了 数值模型将根据实验数据进行检查和修改 直到数值结果与实验数据充分匹配。的 将结合两种方法来检验假设，并确定 电流密度阈值 该模型将用于执行 任何除颤条件的数值实验。

The aims of this proposal are to determine the distribution of myocardial current density during defibrillation and its effect on defibrillation success. One hypothesis of this study is that a minimum current density must be reached within the myocardium in order to achieve defibrillation. A second hypothesis is that this threshold current density is invariant with respect to a given species under homeostatic conditions. Whether threshold myocardial current density is achieved for a given defibrillation attempt depends on the distribution of current throughout the myocardium. This distribution is complex due to inhomogeneity of the heart volume conductor and anisotropy of myocardial conductivity and, in addition, may be altered by such factors as electrode size and placement as well as the presence of acute ischemia and infarcted tissue. A systematic study will be performed to determine the quantitative relationships between these parameters and the myocardial current distribution. The long-term objective is to optimize the delivery of the defibrillation pulse for a given set of clinical conditions. Due to limitations of both experimental and numerical approaches to this problem, this investigation will combine both methods in a complementary fashion. A numerical torso model will be developed for finite element analysis. This model will ultimately be able to predict the current distribution throughout the heart for a given set of transthoracic or transcardiac conditions. In parallel with this work will be the development of a 256 channel data acquisition system for mapping three-component epicardial current density, one-component current density within the myocardium, and activation wavefronts before and after the defibrillatory pulse. The numerical model will be checked against experimental data and modified until the numerical results sufficiently match the experimental data. The two methods will be combined to test the hypotheses and to determine the current density threshold. The model will then be used to perform numerical experiments for any set of defibrillation conditions.