Human Cardiac Reserve Detecting And Evaluating Based On The Relationship Between Cardiac Contractility And Heart Sound

Studying and analyzing heart sound signal has a significant value in assessing cardiac reserve. The decreasing cardiac contractility, which is the main problem of cardiac fatigue patients, congenital injury in cardiac valves and the cardiac mechanical activity obstruction caused by conductive tissue of cardioelectric all can be detected by heart sound. Also heart sound has important diagnostic value that ECG cannot replace. Since heart sound variation and murmur appears before the ECG disorder when cardiovascular disease appears.The achieved works include research and exploitation of a miniaturized hardware module, software designing, data collection and systematic data analysis, as well as studying the cardiac reserve indicators, especially the S1/S2 variability. Specifically works are presented as following:1. A testing system, including hardware and software, has been developed to meet the needs of clinical application. The hardware is divided into two parts, one is front-signal collector and processor, the other is communication network modular (interface). Performance test shows that the non-invasive cardiac reserve monitoring system satisfies the basic design requirements, and meets the cardiac inotropic and chronotropic research needs in the fields of clinical medicine and sports medicine.2. Analysis of heart sound signals. By studying the physiology of heart, heart is regarded as a nonlinear dynamic system. In this paper, after visual analysis of heart sounds, a nonlinear time series analysis of heart sound recognition algorithm based on the dynamic system theory has been proposed in perspective of the complexity. For the first time, the concept of "simplicity" has been adopted as an indicator of heart sound signal quantitative analysis. This paper described the algorithm realization and the MATLAB simulation. The results show that this method can solve the difficulties that energy-based segmentation method can not overcome. This method is independent with changes in signal amplitudes, so the results of extracting the major components of heart sound signals are satisfying. In addition, the method can accurately detect the starting point and the duration of a heart murmur signal, which is of great significance in clinical diagnosis. After the non-linear analysis in heart sound signal, an automatic identification algorithm of heart sound signal components based on "simplicity" envelope of curve is proposed. And the algorithm is applied in the cardiac reserve indicators assessing system.3. Based on the cardiac reserve data among different populations, which measured by designed system, an integrated assessing system to evaluate cardiac reserve (heart rate, cardiac contractility change trend(CCCT), diastole and systole ratio (D/S),S1/S2 ratio, S1/S2 variability and other indices) has been introduced. The cardiac reserve data among different populations such as the official, the patients (hypertension and diabetes), and different age groups has been investigated and evaluated. Furthermore, A new method for detecting and assessing the changes in heart state has been explored, that is the research on the variability and change trend of S1/S2. The breath-holding phonocardiogram test (BHPCGT) has been designed in the study of S1/S2 variability. A new phenomenon---- the reversal of S1/S2 ratio (RS1/S2R) has been discovered. To explore the details of RS1/S2R, we have proposed the S1/S2 change trend, the frequency of RS1/S2R, the start point of RS1/S2R and other correlative indices.This research develops a noninvasive and widely used test technology for evaluating cardiac reserve and demonstrates the effectivity and the feasibility of this method as well as the testing system by investigating and analyzing the cardiac reserve data from different populations such as the academician, the elderly, the official etc. This subject has great theoretical importance and widely application prospect.