心外膜电位标测系统的信号分析方法研究及心外/心内通用复律除颤器的研制

【作者】 周宇；

【导师】 方祖祥；

【作者基本信息】 复旦大学 ， 医学电子学， 2008， 博士

【摘要】 心脏电生理机制研究和心律失常的电治疗仪器研制是人们在心律失常方面开展研究的两个重要方向,二者相辅相成。在心脏电生理机制研究方面,心外膜电位标测技术具有独特优势,同时具有贴靠心脏、定位准确、信息量大和适用于在体标测等特点;其技术中的一个很大难点在于如何对标测到的心外膜电位信号进行有效分析以获取准确完备的信息、进而对心脏电活动规律进行深入探索,具体来说,可包括信号去干扰、特征点识别和信息提取与表达三方面内容。此外,“刺激—标测”技术是一种非常好的心脏电生理机制研究手段,尤其是在心律失常电治疗新方法的探索上;该技术对刺激电源具有较高要求。在心律失常的电治疗仪器研制方面,电击复律除颤器是一种非常有效的治疗仪器,在手术室中、院外急救场合和长期植入式治疗中发挥着重要的作用;但现有产品中缺乏专用于心脏外科手术室中的复律除颤设备。论文针对心外膜电位标测技术和心脏外科手术室专用复律除颤器研制方面的需要而展开。在心外膜电位标测信号分析方法的研究上:以独立元对各电极点投影系数的离散度为干扰独立元选取准则,提出了基于独立元分析的心外膜电位标测信号去干扰新方法;根据特征点时刻心外膜电位标测信号中除极波形的关键特征,提出了基于信号时域信息及其二次B样条小波变换信息的特征点识别算法;提出“时间依赖性”的观点,并基于此设计了具有时间依赖性的波形能量分析方法,以揭示除极波的传播路径;提出“特征点群”的概念,并设计了基于短时波形能量分析的特征点群识别算法,用于定位某一除极波穿越电极片所在区域的时间窗。在上述方法的基础上,设计了一整套心外膜电位标测信号自动联合分析方法:首先,基于独立元分析对心外膜电位标测信号进行去干扰;其次,根据信号及其小波变换进行特征点识别;再次,使用特征点群识别算法自动定位除极波穿越电极片所在区域的时间窗;最后使用波动图、具有时间依赖性的波形能量分析和等时图联合对特定除极波的传播进行分析。此外,根据“刺激—标测”技术的要求,开发了一种基于UC3845的DC-DC反激式开关电源,应用于“刺激—标测”实验。在心脏外科手术室专用复律除颤器的研制方面,以心外/心内通用复律除颤器为研制目标,分四个模块进行系统的硬件和程序开发:复律除颤主模块、阻抗检测模块、R波识别模块和供电模块,分别进行设计和调试;高压、低压电路之间全部进行了隔离以确保安全。而后,对其中的R波识别模块进一步改进,设计了一种基于心电信号幅度及其微分信息的全硬件R波同步触发电路,并开发了一套基于Labview和DAQ6062E的测试系统,以测试该R波同步触发电路的性能。实验结果表明,基于独立元分析的去干扰方法较有效地去除了心外膜电位标测信号中的外界非平稳噪声和伪迹等干扰,真实的除极信息得到保留或突出;基于信号幅度及其样条小波变换的特征点识别算法较精确地识别到心外膜电位标测信号的特征点位置;基于短时波形能量分析的特征点群识别算法较准确地定位出除极波穿越电极片所在区域的时间,使后续分析能够聚焦于特定除极波的传播;在此基础上,具有时间依赖性的波形能量分析揭示了特定除极波传播的路径,结合波动图和等时图,除极波的信息得到了较全面的揭示和表达;根据“刺激—标测”技术的要求而开发的反激式开关电源能够在刺激期间提供足够大的电流、且刺激电压下降的幅度保持在允许阈值之上,同时刺激电压恢复迅速;针对心脏外科手术中的需要而研制的心外/心内通用复律除颤系统可快速充电至最高允许电压,准确释放出低能量双相指数截尾波进行电击,预设能量的释放准确,释放能量的计量也较精确,阻抗检测结果较准确,可进行分级阻抗补偿工作;新的R波同步触发电路可自动准确定位R波、阳性预测率高、延时小、危险性低、灵敏度较高,测试系统能以MIT-BIH Arrhythmia Database为数据源、输出心电信号、实时观察并记录R波识别结果。因此,基于去干扰、特征点识别、特征点群识别、具有时间依赖性的波形能量分析、波动图和等时图的一整套心外膜电位标测信号自动联合分析方法能够较有效地去除信号中的干扰成分、精确识别特征点、较准确地定位除极波穿越电极片所在区域的时间、全面揭示和表达除极波传播的信息,帮助研究人员更好地理解心外膜电活动现象、进而揭示其中的规律,所以该方法适用于心外膜电位标测系统中的信号分析工作。反激式开关电源达到设计要求,适用于“刺激—标测”技术。心外/心内通用复律除颤系统具备了在心脏外科手术中以心外或心内电击方式实施电击复律除颤的能力;新的R波同步触发电路能够自动为复律除颤器提供较准确、安全的R波识别信息、支持其进行R波同步电击复律,基于Labview和DAQ6062E的测试系统使PC机同时成为心电信号发生器、示波器和数据记录仪,能够提高工作效率,亦可方便地应用于其它领域。总体来说,在心律失常的研究方面,从心脏电生理机制研究和心律失常的电治疗仪器研制两个方向入手,所开展的工作取得了一些成功,成果比较具有实际意义。更多还原

【Abstract】 The mechanism research of cardiac electrophysiology and the development of electrical therapy apparatus are two important aspects supplementing each other in the research of arrhythmias. In the aspect of cardiac electrophysiological mechanism research, epicardial potential mapping technology has unique advantage for being with characteristics of exact positioning, large information and in vivo mapping at the same time. One of its technique difficulties is how to analysis the epicardial potential mapping signals effectively and to extract the exact and entire information to explore home the regularities of electrical activations of the heart. In detail it includes 3 aspects: removing interferences, characteristic recognition, information extraction and expression. Moreover "stimulation-mapping" is a very good mean for the research of cardiac electrophysiological mechanism, especially in the exploration of new electrical therapy methods, and the requirement for its stimulation power is high. In the aspect of the development of electrical therapy apparatus for arrhythmias, cardioversion-defibrillation with discharge is a very effective electrical therapy and is important in first-aid occasion out of hospital and long-term therapy. But the development of special cardioverter-defibrillator for heart surgery is lacking very much.This dissertation aimed at the requirements of epicardial potential mapping technology and the special cardioverter-defibrillator for heart surgery. In the aspect of research for epicardial potential mapping signals processing: a new arithmetic for removing interferences was designed based on independent component analysis and the interference independent component selection measurement was the dispersion of independent component’ projection coefficients to every electrode; a new characteristic recognition arithmetic based on the information of signal and its B-spline wavelet transform was designed according to the key features of depolarization waveform in epicardial potential mapping signals; the concept of "time-dependence" was put forward and the time-dependent waveform energy analysis was designed based on this concept; the concept of "characteristics" was put forward and the characteristics recognition arithmetic was designed based on short time waveform energy analysis to locate the time window when special depolarization wave traversed the electrodes plaque. A whole automatic united analysis method was designed based on foresaid arithmetic: first to remove interferences in the epicardial potential mapping signals based on independent component analysis; then to recognize characteristic according to signal and its wavelet transform; then to locate the time window when special depolarization wave traversed the electrodes plaque with characteristics recognition arithmetic; in the end to analyze the spread of special depolarization wave unitedly with dynamic iso-potential map, time-dependent waveform energy analysis and isochrones map. In addition, to supply multi-channel electrical stimulator, a DC-DC flyback switch mode power supply based on high performance current mode controller UC3845 was developed according to the requirements of "stimulation-mapping". In the aspect of the development of special cardioverter-defibrillator for heart surgery, aiming at the cardioverter-defibrillator in epicardial and endocardial manner, the development of hardware and program of the whole system included 4 modules: cardioversion-defibrillation main module, impedance detection module, R-wave synchronization module and power supply module. The 4 modules were designed and debugged respectively. And high-voltage circuit was isolated from low-voltage circuit to insure the security. Whereafter R-wave synchronization module was improved on. A new whole-hardware R-wave synchronization circuit based on electrocardiogram and its differential information was designed and a test system based on Labview and DAQ6062E was development to test the performance of the R-wave synchronization circuit.The results of experiments indicated: the new arithmetic based on independent component analysis for removing interferences removed the interferences including non-stationary noises and artifacts in epicardial potential mapping signals effectively and the true depolarization information was reserved and strengthened.; the new characteristic recognition arithmetic based on the information of signal and its B-spline wavelet transform recognized the characteristic in epicardial potential mapping signal accurately; the characteristics recognition arithmetic based on short time waveform energy analysis located the time window when special depolarization wave traversed the electrodes plaque exactly and the subsequent analysis could focus on the spread of special depolarization wave; on this basis, time-dependent waveform energy analysis revealed the spread route of special depolarization wave and the information of depolarization wave was expressed roundly with dynamic iso-potential map and isochrones map; the flyback switch mode power supply could supply enough current during the period of stimulation and keep the stimulation voltage above the threshold value at the same time, and the stimulation voltage could come back rapidly after stimulation; the system aiming at the special cardioverter-defibrillator for heart surgery could charge rapidly to the highest voltage and discharge with biphasic truncated exponential waveform exactly, the discharge of presupposition energy was exact, the measurement of discharge energy was accurate, the impedance detection result was relatively accurate and the impedance classification compensation could be fulfilled; the new R-wave synchronization circuit could locate R-wave automatically and accurately with high positive prediction rate, small delay, low risk and high sensitivity; the test system could output electrocardiogram based on MIT-BIH Arrhythmia Database, observe real-timely and record the R-wave identification result. In conclusion: the whole automatic united analysis method based on arithmetic for removing interference, characteristic recognition arithmetic, characteristics recognition arithmetic, dynamic iso-potential map, time-dependent waveform energy analysis and isochrones map can remove the interferences effectively, recognize the characteristic accurately, locate the time window when special depolarization wave traversed the electrodes plaque exactly and reveal and express the information of depolarization wave roundly, it can help researchers understand the electrical activations in epicardium better and then proceed to the next step to reveal the hidden regularities, so it’s fit for the signal processing in epicardial potential mapping system; the flyback switch mode power supply reaches the design requirements and is fit for "stimulation-mapping"; the system aiming at the special cardioverter-defibrillator for heart surgery has the ability to perform cardioversion-defibrillation with discharge in epicardial or endocardial manner in heart surgery; the R-wave synchronization circuit can supply accurate and safe R-wave identification information for cardioverter-defibrillator automatically to support the R-wave synchronization discharge; the test system based on Labview and DAQ6062E makes PC turn into electrocardiogram waveform generator, oscillograph and data recorder at the same time, it improves work efficiency and can be used in other fields expediently. So in the research of arrhythmias, starting with the two aspects of the mechanism research of cardiac electrophysiology and the development of electrical therapy apparatus, some success is obtained in the work and the results have practical significance.更多还原