Research On Chronic Cardiovascular Disease Detection Technology Based On ECG Signal And PPG Signal

Nowadays,people suffer a lot from the cardiovascular disease which is very hard to detect.Especially the cardiovascular disease becomes a more and more serious threat to the elderly people.Thus its preventions and treatments have attract much attention in modern medical research.The ECG and PPG can show information about cardiovascular disease which could be used to evaluate the condition of heart and cardiovascular.By analyzing the theoretical fundamental and waveform features of ECG and PPG,collecting the information of HRV,blood pressure and etc.,processing these signals with specific algorithm,we finally achieved a system to detect the cardiovascular disease.The detection system includes the design of the detection scheme and the construction of the acquisition circuit.The design and implementation of the detection scheme is the main content of this paper.Designing the detection scheme,we firstly pre-process the ECG and PPG and detected the feature points.We study the waveform and signal characteristics of two kinds of signals.Then we use wavelet decomposition and threshold denoising to filter the baseline drift,power frequency interference and EMG interference of ECG and PPG signals.We use mathematical morphology and windowed processing to detect the QRS complex wave,P wave and T wave bands of ECG signals.We use extremum method and differential method to detect the PPG signals' crests and troughs.Secondly,by studying the detection methods of heart rate,heart rate variability and blood pressure,we achieve three detection schemes.The first one is HR and HRV detection scheme based on ECG,which can give us the average heart rate by calculating the mean of R-R interval of ECG signal and the HRV by time domain analysis.The second one is the blood pressure detection scheme based on Pulse Wave Transit Time(PWTT).By using this scheme,the linear model of systolic blood pressure(SBP)and PWTT can be established by calculating the value of PWTT.The third one is the blood pressure detection scheme based on chord pulse recognition and pulse wave.It realizes the partition processing and detection of blood pressure by classifying input PPG signal into the hypertension group and the normal blood pressure group as well as establishing the linear model of SBP,DBP and pulse width and pulse rate ratio(w/pr)respectively.As for the acquisition circuit hardware part,we focus on the four functional modules of ECG and PPG signal acquisition circuit.The main control module based on M2 chip and Bluetooth transmission module based on CC2540 chip are the core parts of the acquisition circuit.The former one realizes the acquisition and processing functions of ECG and PPG signals and the latter one realizes the wireless transmission function of acquisition signals.Finally,we design an experiment system to evaluate the heart rate and blood pressure detection scheme.The heart rate and blood pressure values detected by the algorithm program are used as experimental data group,and the heart rate and blood pressure values measured by stethoscope and OMRON sphygmomanometer are used as control data group.Through Bland-Altman analysis method,it is verified that the detection value of the algorithm is in good agreement with the measurement value of medical instruments,and the feasibility of the detection scheme in this paper is further verified.