Lumped parameter estimation for the embryonic chick vascular system: a time-domain approach using MLAB

We have evaluated several lumped parameter analog models for the early chic k embryonic vascular system that may be used to infer loading characteristi cs of the developing heart. We measured dorsal aortic pressure and flow sim ultaneously with a servo-null pressure system and a pulsed Doppler velocime ter. Four different analog circuit models were chosen for comparisons. We f ormulated the time-domain differential equations specifying the relations b etween pressure and now in the models, and then estimated the lumped parame ters that produced the best lit. The MLAB mathematical modeling software wa s used for solving differential equations, and for minimizing the differenc e between model-predicted values and experimental data. The traditional thr ee-element Windkessel model with an added inductance term was most often th e best-fitting model. This is compatible with the previous study using a fr equency-domain approach. The procedures developed for the current study are adaptable for the study of a variety of nonlinear models, and distributed parameter models for mammalian cardiovascular development with mechanically , pharmacologically, or genetically altered conditions. (C) 2000 Elsevier S cience Ireland Ltd. All rights reserved.