【作者】 陈奎孚；

【导师】 罗致诚； 高小榕；

【作者基本信息】 中国协和医科大学 ， 生物医学工程， 2000， 博士

【摘要】 HRV和BPV已成为评价心血管系统调节功能的重要参数，但这仅是心血管系统变异的侧面表现。若全面深入理解其本质，无论在机制上还是在处理手段方面都存在大量的问题需要解决。本文对其有关的理论问题进行了较为深入地研究。主要工作与结果如下： 1．血管容积变异的提出 作者详尽地总结了心血管系统变异的机制与临床的研究进展和所存在的问题，在此基础上作者认为血管容积变异历程所含信息更为丰富，并能将心脏与微循环之间联系起来，初步观察已证实了该观点的正确性。 根据HRV和BPV的低频成分与微循环自主舒缩频带重叠这一事实，它们二者之间可能存在某种联系，而界于心脏和微循环之间的血管容积变异应包含更丰富的信息，因为它既与心脏泵血有关，又与外周大血管和微动脉自主舒缩有关。比较相关的研究后发现，肢体阻抗容积图在研究心血管系统变异方面具有独特的优势：①对机体干扰比较小，这可避免血压测量中充放气所给患者带来的不适，以及由此而引起的对自主神经的干扰；②阻抗容积图容易得到整个时程信息，这避免血压变异中仅依靠舒张压、收缩压和平均压几个参数的片面性；③阻抗容积图的不同特征量受心脏、血管、微循环影响程度不同，因而便于从多视角观察心血管系统变异。 对肢体阻抗血流图的拍拍变异进行了初步分析，观察到了如下几个方面的现象：①阻抗容积图整体以及大多数的特征量也存在类似HRV和BPV的LF和HF谱峰，特别是脉率变异与HRV基本相似；②阻抗容积图低频变异有类似宽带的特性；③阻抗容积图的重搏前波变异LF功率大于其他波LF功率，其原因可能涉及微循环的自主舒缩：④HRV极低频与血流极低频功率谱之间存在明显差异，HRV表现出典型的1／f~β现象，而血流图极低频成分随频率趋于零而下降。 2．利用阈值收缩法直接去除色噪 建立了直接由色噪功率谱估计小波变换各尺度噪声方差的公式，这既避开了现有文献去除色噪方案中的白化滤波器设计，又避免了两次滤波操作，可有效(?)减少运算量。同时，由于未涉及白化滤波，故也不存在因滤波器与色噪模型不匹配所带来的精度问题。将这种方法应用于阻抗血流图去噪，取得良好效果。 3．特征点检测与时频参数精细估计 提出了奇异点按对称性分类的概念，按照这个概念，奇异点检测中的小波选择更具目的性和指导性，即对中心对称类型奇异采用偶函数小波，而轴对称型奇异采用奇函数小波，可使小波变换在奇异点处出现极大值。将小波变换应用于心电图的R波检测，比较了采用Marr小波和二次样条小波的变换在R波位置的局部性态。通过数值试验发现，把R波的升支(或降支)作为中心对称性奇异比把R波作为δ类奇异更为合理。更多还原

【Abstract】 Heart rate variability (HRV) and blood pressure variability (BPV) have been taken as important roles in evaluating the regulating function of cardiovascular system, but they are not the whole manifestation of cardiovascular system variability (CVSV). No matter in the mechanism or the analysis method, there are still a lot of problems needing to be solved. Some of these problems are studied in depth in this dissertation.1. The presentation of vascular plethysmogram variabilityThe progresses and issues in the mechanism research and clinical study of CVSV were reviewed systematically, and the advantages of vascular plethysmogram (VP) were summarized. The most important potentiality of the VP measurement is capable to observe the comprehensive information of the heart linked with microcirculation and vasomotion. Compared with the blood pressure meansurement, the whole time-history of VP can be obtained without extraneous tension to the patient being tested, hence CVSV is prone to be investigated by means of vascular plethysmogram variability(VPV).In this dissertation, the VPV was investigated in preliminary, and many interesting phenomena were found. Firstly, VPV and most of VP characteristic parameters’ beat-beat variability possess the same LF band and HF band as HRV and BPV. Secondly, LF of VPV exhibits width-like band feature. Thirdly, The LF power of tidal wave amplitude variability is larger than that of other parameters. Lastly, the very low frequency band of HRV behaves as the typical power law, but not of VPV.2. The direct suppressing color-noise by threshold shrinkage methodThe key to threshold shrinkage method is threshold estimating, which were accomplished by direct estimation from color noise spectrum in this dissertation. Filter designing and twice filtering in the literature method are not necessary in this algorithm.3. Characteristic point detecting and high resolution estimating of parametersThe concept of symmetry property of singular point was proposed. According to this concept, blindness can be avoided in wavelet selection in characteristic point detecting, i.e., to make wavelet transform maximum at singular point, odd wavelet is used for centrosymmetry singular type, even wavelet for the axially symmetry.The continuous wavelet transform were used to detect the R-peaks of electrocardiographic(ECG). The R-peak local traits of wavelet transform with Marr更多还原