| The purpose of this study is to propose an extendable mathematical model for the cardiovascular system including baroreflex mechanism, and simulate the characteristics of haemodynamics as well as the role of baroreceptor in regulating cardiovascular system. The main tasks and results are summarized as follows,√ To solve the existing problems in the macro model of cardiovascular system, a model including heart, head and neck circulation, pulmonary circulation, coronary circulation, abdomen circulation and extremity circulation was developed. Bond graph method which has been proved a valid method for modeling physiological systems was applied to model the heart and vascular network. Totally 54 equations construct the cardiovascular system model. The model was simulated by coupling the heart and vascular network. The input parameters for cardiovascular model are heart and vascular network parameters such as cardiac cycle, heart elastance, vascular compliance and vascular resistance, while the outputs are the blood pressure and flow wave on each segment of vascular, and the cardiovascular parameters such as stroke volume, cardiac output, eject fraction, energy and oxygen consuming in each cardiac cycle, and so on.√ In order to test the validity of the model, the haemodynamic parameters under normal physiological states were simulated and the results are of good agreement with physiological experimental data, thus the efficiency of the model was verified. By adjusting the initial condition parameters of the model, the simulation for pathological features of cardiovascular system, such as atherosclerosis, stenosis in resistance vesel, hypertension and stenosis in left subclavicle artery was implemented and the results are consistent with human pathological features. In addition, the variation of arterial blood pressure on the development of atherosclerosis and stenosis in resistance vesel were implemented and the results are accordant with clinicalfeatures.?S Nervous modulation was considered on the base of cardiovascular model, thus the baroreflex model was built. The development of hypertension with baroreflex modulation was simulated by coupling the baroreflex model and cardiovascular model. The results suggest that nervous modulation plays an important role in the development of hypertension. A mathematic model of ventricular hypertrophy under hypertension was established. The effects of hypertension to the thickening of left ventricle wall with and without baroreflex mechanism were simulated. The results suggest that baroreflex mechanism can mitigate the effects of hypertension to the thickening of left ventricle, and can protect the cardiovascular system.In conclusion, the cardiovascular model established in this study provides an extendable simulation tool for studying the physiological and pathological characteristics of cardiovascular system. Owing to its flexibility, the model can be further improved and thereby applied for research and clinical purpose. |
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