Cardiovascular response to postural stresses: a mathematical analysis

Cardiovascular alterations occurring in the short period following a postural stress are analyzed using a mathematical model of the baroreceptor control system. The model embodies the main arterial and venous hemodynamic parameters in both systemic and pulmonary circulations, stroke volume dependence on preload and afterload, and the regulatory action of baroreceptors on systemic arterial resistance, systemic venous capacity and heart rate. Model predictions concerning the response to lower body negative pressure maneuvers in healthy subjects substantially agree with experimental results as to the pattern of the main hemodynamic quantities (stroke volume, cardiac output, systemic resistance, mean arterial pressure, heart rate). In perspective, the model may be employed to study cardiovascular alterations in pathological conditions associated with symptoms of orthostatic hypotension