Modeling cardiovascular hemodynamics in a model with nonlinear parameters

One of the major questions in cardiovascular physiopathology is to distinguish between a change in ventricular performance or vascular system and to provide quantitative evaluation of both cardiac and vascular functions. For a nonlinear lumped parameter model of the cardiovascular system, the hemodynamic and left ventricular volume variations were investigated for changes in characteristic parameters. A state-space form of the model, allows to take into account parameters like ventricular compliance, changes in preload or afterload. Besides the values associated with normal clinical conditions, some changes in contractility and afterload conditions were simulated, particularly associated with specific pathological conditions of ischemic patients. In order to evaluate the left ventricular-arterial coupling, the cardiovascular nonlinear model equations for the ejection phase were solved using code written in Matlab. Also, pumping capability of the left ventricle was investigated using the transfer function associated with another cardiovascular model.