【作者】 夏灵；

【导师】 吕维雪；

【作者基本信息】 浙江大学 ， 生物医学工程， 1995， 博士

【摘要】 以往的心电逆问题研究,要么从体表电位推断心脏的等效源,要么从体表电位分布推断心外膜电位分布。对于前者,由于心电源的等效方法有很多,人们事先很难知道该用哪一种等效方法,心电源可以这样假设,也可以那样假设。即使心电源假设得比较合理,由于存在数学上的病态特性,所求出的解也是很不准确的,因此这种方法的实际应用意义不大。对于后者,只是从理论上讲,逆解得出的心外膜电位分布比体表电位分布具有更高的诊断分辨率,但由于逆解的不很准确性,真正将这种方法应用于临床还没有见到。这二种研究方法的最大不足之处是没有将体表电位与心脏的电兴奋传播过程联系起来。近年来心脏电兴奋传播仿真模型(心电正问题)的发展使得我们能够研究心脏电兴奋传播过程与体表电位之间的关系。将心电正问题与逆问题有机地结合起来就可产生一种新的心电逆问题研究方法,即我们所提出的基于心电仿真模型参数解的心电逆问题研究方法。在心电仿真模型中,心脏电兴奋传播过程是由一系列心脏电生理特性模型参数决定的,因此只要能从体表电位数据推知心电仿真模型参数,就可以确定心脏的电兴奋传播过程。这种方法的最大优越之处是从逆解得出的模型参数可以得知心脏病灶的定量信息(如病灶的位置、范围、程度等)。本文的主要工作包括:一、心电逆问题新方法研究系统地介绍了现有心电逆问题研究的方法及其进展。在分析了以往逆问题研究方法的欠缺后,在国际上首先提出了一种基于心电仿真模型参数解的逆问题研究新方法,并给出了一个逆问题研究新方法的研究方案。通过对WPW预激综合症室内预激点定位的试验表明其逆解得出的预激点位置误差一般不超过4.5 mm。通过在模型产生的体表电位数据中加噪声和电极位置偏移的方法来模拟实测的体表电位数据,试验结果表明体表电位数据在存有信噪比为15的噪声和电极位置最大偏移量不超过10 mm的情况下,逆解的稳定性良好。二、心电仿真模型编辑器的开发基于心电仿真模型参数解的逆问题研究新方法需要积累大量的有关体表电位与心脏状态之间关系的知识,因此需要进行大量的仿真研究。原LFX心电仿真模型对模型参数的设置是基于数据文件逐点进行的,既繁琐耗时,又易出错。因此我们开发了模型编辑器,以形象化的图形方式来对模型参数进行设置,并将参数编辑、仿真运算、结果显示集于一身,使心电仿真模型形成一个易于操作的系统软件。此外,我们还把它从DOS运行环境移植到Windows环境下,以利于今后实现该软件的进一步版本升级。更多还原

【Abstract】 Previous electrocardiographic inverse problem studies have focused on deducing equivalent heart sources or reconstructing epicardial potentials from the measured body surface potentials. Many equivalent representations of the cardiac sources can be used. We do not know in advance which equivalent representation is more suitable, we can employ the equivalent representation in this way or in that way. Even if the employed equivalent representation is suitable for cardiac sources, the inverse solutions are not accurate because of the ill-posed nature of the inverse problem. So the inverse problem in terms of equivalent heart sources has little applicability. For the inverse problem in terms of epicardial potentials, theoretically, the reconstructed epicardial potentials’ posses higher diagnosis resolution compared with the body surface potentials, however, the inverse solutions of this approach are also not accurate enough for clinical applications. The most shortcoming of these two approaches is that both of them have not related the body surface potentials to the excitation propagation process in the heart.The developments of the excitation propagation-type heart models (forward problems) enable us to study the relationship between the body surface potentials and the excitation propagation of the heart. Combining the forward problem with the inverse problem can produce a new approach to the inverse problem, i.e., solutions in terms of heart-torso model parameters, which was introduced by us for the first time in the world. In the heart-torso model, the heart excitation propagation depends on a set of model parameters, so the heart excitation propagation should be determined if we can deduce the model parameters from the body surface potentials. The most important advantage of this approach is that the quantitative information of the heart disease (the position, the range and the seizure degree of the focus, etc.) could be determined from examination of the recovered heart-torso model parameters.The author has done the following research work:1. Research work on electrocardiographic inverse problemAfter reviewing the previous electrocardiographic inverse problem studies, the author introduced a new approach to electrocardiographic inverse problem studies, i.e., solutions in terms of heart-torso model parameters, and designed a research scheme. To verify the validation of the new method, the author used the approach to localize the site of ventricular preexcitation with simulated body surface potential data in mimic patients with Wolff-Parkinson-White (WPW) syndrome. The inverse recovered preexcitation site was in close agreement with the true preexcitation site, usually the position error更多还原