Time-frequency analysis of blood pressure and flow signals in Spontaneously Hypertensive Rats and Wistar Kyoto Rats

In this paper, the Wavelet Transform (WT) and Hilbert-Huang Transform (HHT) 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 both WT and HHT can reveal five characteristic frequencies, corresponding to the cardiac, respiratory, myogenic, neural and endothelial cell activity, and HHT has better frequency resolution than WT in the low frequency band (0-0.1Hz).The signal energy and signal amplitude for SHRs´ cardiac, respiratory and endothelial cell activities are significantly lower in comparison with those of WKYs. 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.