Research And Analysis Of Blood Pressure And Flow Signals In Spontaneously Hypertensive Rats

A number of investigations have shown that the elevated blood pressure can cause changes of hemodynamic parameters in the blood circulation system, which lead to the endothelial, cardiac and other physiological abnormalities. These changes in physiological rhythm are reflected in blood pressure and flow signals. Therefore, hemodynamic parameters can be studied through the analysis of blood pressure and flow signals. The paper provides effective information of hemodynamic characteristics for the early diagnosis and prevention of cardiovascular disease and reduces the incidence of hypertension and other cardio-cerebral vascular risk.In this paper, we compute hemodynamic parameters firstly. Then the Wavelet Transform (WT), Hilbert-Huang Transform (HHT) and Synchrosqueezed Wavelet Transform(SWT) are adopted to analyze the blood flow signals in the common carotid arteries and the blood pressure signals in the ipsilateral common femoral arteries in Spontaneously Hypertensive Rats (SHRs) and Wistar Kyoto Rats (WKYs). Five characteristic peaks are extracted and compared by t-test to assess the physiological differences between SHRs and WKYs. It is found that pulsatility index, peripheral resistance and dynamic resistance of SHRs are higher than WKYs’, However, only peripheral resistance and dynamic resistance have significant difference. Each one of the three time-frequency methods can reveal five characteristic frequencies, corresponding to the cardiac, respiratory, myogenic, neural and endothelial cell activity. Wavelet spectrum is the smoothest. HHT gets the most frequency information. SWT has the highest frequency resolution. In comparison with those of WKYs, the characteristic frequency for SHRs’ cardiac and endothelial cell activities are higher than WKYs, however, the signal energy and signal amplitude for SHRs’ cardiac, respiratory and endothelial cell activities are significantly lower. Compared with the results of blood pressure signals, more distinct characteristics could be obtained from the blood flow signals. Thus, it could be concluded that the blood flow signals contain more useful information than the blood pressure signals do.These results provide some clues to assess arterial, endothelial and cardiac function in the hypertensive development by detecting and analyzing the blood pressure and flow signals in the common carotid arteries and also compared the difference between the three kinds of time-frequency analysis methods which applied to the blood pressure and flow signals.