The Study Of Cardiac Reserve Monitoring System Based On Telephone Network

Heart sound is an indication of mechanical movement in heart and cardiovascular system, which contains some important physiological and pathological information. The recognition of heart sound signal is very important to cardiovascular disease diagnosis, of which the accuracy and reliability directly affect the diagnosis and treatment. So the development of cardiac reserve monitoring system which aims to be home and daily life oriented and able to timely monitor the state of heart become essentially important. A kind of cardiac reserve monitoring system has been put forward in this thesis based on telephone network. The non-invasive, convenient, cheap characteristic and quantified monitoring and evaluation function enable the system be widely popularized in families and communities.The hardware of this system has achieved heart sound signal acquisition, processing, local and remote data transmission. The local data communication employs USB interface to send heart sound signal data to local computer, through which patients are aware of their cardiac status in real time. The remote data communication adopts a modem to modulate heart sound signal to the telephone network transmission band for transmission, through which doctors can easily access to patients'cardiac status and implemented remote monitoring. The software has devoted to preliminary study for automatic identification of heart sound signal under the existing analysis tools. From the heart sound generation mechanism, a nonlinear time series analysis of heart sound recognition algorithm based on the dynamic system theory has been proposed in this thesis. Most of previous algorithms are focus on energy or spectrum and the common problem of these methods is a large extent frequency overlap between noise energy and the major components of heart sound, which brings to automatic segmentation great difficulties. In order to evaluate the reliability and accuracy of this proposed algorithm, a comparative study among normal heart sound signals at different noise environment has been conducted. The result shows that the segmentation performance of this method has a distinct advantage when it applied to the signal with serious noise interference.By using the cardiac reserve monitoring system, the author studied the basic indicators of heart sound among college students: heart rate (HR) and cardiac contractility change trend (CCCT), analyzed a number of heart sound sample from various individuals under different conditions (at rest and following exercise). From the results a conclusion can be reached: HR and CCCT can be used to evaluate cardiac reserve status because of their highly correlation coefficient. This indicates that the cardiac monitoring system can be used to monitor cardiac reserve. As a measure of heart status this method is able to provide a quick and easy way to evaluate cardiac reserve as well as an objective indicator for physical assessment.