A Preliminary Research On Some Theoretical Problems Involved In Cardiovascular System Variability Study

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...