MATHEMATICAL SIMULATION OF HEMODYNAMIC VARIATIONS IN THE FETAL SIDE OF THE HUMAN PLACENTA IN THE PRESENCE OF INCIPIENT RESISTIVE PATHOLOGIES

Objective: This work deals with the simulation of the fluid dynamics o f the fetal side of the human placenta and is aimed at reaching a deep er knowledge and a more correct interpretation of the influence that h emodynamic parameters, such as blood flow rate and pressure, have on t he physiologic and pathologic behavior of both this organ and the fetu s. Methods: The feto-placental circulatory system is divided into four main sections: heart, nonplacental circulation, aorta, and placental circulation. Fetuses weighing 2.5 kg, 36-38 weeks old by gestational a ge, are considered. Hemodynamic and geometric parameters are calculate d at each instant of the fetal cardiac cycle. Pathologic states are si mulated by proportionally increasing the vessel resistance to blood fl ow, either in the whole placenta or in each placental section. Two dif ferent approaches are adopted in simulating the system: steady cardiac output (SCO) or steady cardiac work (SCW) during the cardiac cycle. T o check the response of the system to parameter variation under both S CO or SCW conditions, a sensitivity analysis is used. Results: The out comes of the simulation of physiologic conditions match the results of clinical measurements. The results concerning the pathologic simulati on allow us to quantify the variation of the hemodynamic parameters (t he percent reduction of both the placental flow and the peak velocity together with its time shifts) with respect to the cardiac cycle durat ion. Conclusions: The results obtained by the simulation model need to be verified against some real situations, but at the moment, it seems quite unsuitable to perform the appropriate in vivo measurements. Nev ertheless, the results obtained could be useful for clinical purposes in performing early diagnoses of pathologies affecting the fetal side of the human placenta that could be otherwise detected only by invasiv e measurements.