A closed-loop model of the canine cardiovascular system that includes ventricular interaction

A closed-loop model of cardiopulmonary circulation has been developed for t he study of right-left ventricular interaction under physiologically normal and altered conditions. The core model provides insight into the effects o f ventricular interaction and pericardial mechanics on hemodynamics. The co mplete model contains realistic descriptions of (a) the interacting ventric ular free walls and septum, (b) the atria, (c) the pericardium, and (d) the systemic and pulmonary vascular loads. The current analysis extends previo us work on ventricular interaction and pericardial influence under isolated heart conditions to loading conditions imposed by a closed-loop model of t he circulation. A nonlinear least-squares parameter identification method ( Levenberg-Marquardt algorithm) is used, together with parameter sensitivity analysis, to estimate the values of key parameters associated with the ven tricular and circulation models. Pressure measurements taken at several ana tomical locations in the circulation during openchest experiments on dogs a re used as data in the identification process. The complete circulatory mod el, including septal and pericardial coupling, serves as a virtual testbed for assessing the global affects of localized mechanical or hemodynamic alt erations. Studies of both direct and series ventricular interaction, as wel l as the effect of the pericardium on cardiac performance, are accomplished with this model. Alterations in model parameter values are used to predict the impact of disease and/or clinical interventions on steady-state hemody namic performance. Additionally, a software package titled CardioPV has bee n developed to integrate the complete model with data acquisition tools and a sophisticated graphical user interface, The complete software package en ables users to collect experimental data, use the data to estimate model pa rameters, and view the model outputs in an online setting. (C) 2000 Academi c Press.