Interaction between carotid baroregulation and the pulsating heart: a mathematical model

Abstract

A mathematical model of short-term arterial pressure control by the carotid baroreceptors in pulsatile conditions is presented. The model includes an elastance variable description of the left and right heart, the systemic (splanchnic and extrasplanchnic) and pulmonary circulations, the afferent carotid baroreceptor pathway, the sympathetic and vagal efferent activities, and the action of several effector mechanisms. The latter mechanisms work, in response to sympathetic and vagal action, by modifying systemic peripheral resistances, systemic venous unstressed volumes, heart period, and end-systolic elastances. The model is used to simulate the interaction among the carotid baroreflex, the pulsating heart, and the effector responses in different experiments. In all cases, there has been satisfactory agreement between model and experimental results. Experimental data on heart rate control can be explained fairly well by assuming that the sympathetic-parasympathetic systems interact linearly on the heart period. The carotid baroreflex can significantly modulate the cardiac function curve. However, this effect is masked in vivo by changes in arterial and atrial pressures. During heart pacing, cardiac output increases with frequency at moderate levels of heart rate and then fails to increase further because of a reduction in stroke volume. Shifting from nonpulsatile to pulsatile perfusion of the carotid sinuses decreases the overall baroreflex gain and significantly modifies operation of the carotid baroreflex. Finally, a sensitivity analysis suggests that venous unstressed volume control plays the major role in the early hemodynamic response to acute hemorrhage, whereas systemic resistance and heart rate controls are a little less important.

Modeling the Dynamics of the Cardiovascular-respiratory System (CVRS) in Humans, a Survey

“…Of course, there is a number of phenomena where these simplifications in the models are not permitted. Compare for instance [92][93][94] where the connection between pulsatility of blood flow and baroreceptor action is considered.…”

“…Pulsatility can be obtained by considering the ventricles as compliance vessels with time varying compliance (in this context one usually considers the elastance of the ventricle which is the reciprocal of the compliance) and inflow and outflow valves (see [27][28][29]. For interaction of pulsatility and baroceptor dynamics see [92][93][94] and [26,66].…”

Mathematical modelling of the cardiovascular system and skeletal muscle interaction during exercise

“…However, the vagal activity and the chemoreflex effect influence the resistances, so that we have to consider more state variables. We model the baroreflex as in [23], that is we define for i ∈ {sm, sp, o}:…”

“…. ) are reported (undefined values are as in [23]); however, they have to be adapted when simulations are carried out for different subjects.…”

Analysis of cardiovascular instability by a mathematical model of baroreflex control

“…[3]. Aim of the present work is to use a modified version of this model to study conditions leading to instability of the cardiovascular regulation system, with the appearance of SAP and HR fluctuations.…”