A closed-loop model of the ovine cardiovascular system.

We develop a closed-loop model of the ovine cardiovascular system, with the long term goal of developing a platform for simulating the hemodynamic efficacy of cardiopulmonary assist devices implanted and tested in this animal. The modeling of the systemic circulation is distributed and divided into subsystem circulations. Nonlinear aspects of the systemic venous system are included, such as the pressure-volume relation (PVR) of the systemic veins. In addition, a lumped model of the neural system controlling blood pressure is incorporated. The complete model provides good approximations to measured data from healthy reclining sheep. Moreover, it can predict the hemodynamic changes that accompany pre-load variation upon standing, and the short-term neurally mediated cardiovascular responses that attend this imposed orthostatic stress. We conclude that the model can serve as a simulation platform for evaluating cardiovascular and pulmonary assist devices.