A Differential Model of the Baroreflex Control of the Cardiovascular System During a Tilt Test

In this paper, a differential model of the cardiovascular system and its baroreflex control is presented. This simplified model of the circulation includes the left heart, arterial and venous compartments, the afferent baroreceptor pathway, the sympathetic and vagal efferent activities and excitation-contraction coupling at the cardiac muscle level. The model is used to simulate the interactions among the baroreflex control loop, the pulsating heart and the effector during a graded orthostatic tilt. There is a satisfactory agreement between the model and experimental results illustrated through heart rate variability analysis. Experimental data on heart rate control can then be explained fairly well by a rather simple action of the sympathetic-parasympathetic system on the heart rate. The output of the proposed model are usually measured cardiovascular signals. An objective is to use it in model-based signal processing in order to assess the short-term control of cardiovascular system.