FETAL HEART MODELING BASED ON A PRESSURE-VOLUME RELATIONSHIP

Study of the cardiovascular system of the human fetus is based on noni nvasive measurement methods such as Doppler echography systems. The ci rculation conditions in fetal vessels are usually evaluated by resista nce indices, giving limited physiological information on distal territ ories such as the placenta or the brain. To enhance the understanding of human fetal haemodynamics, a numerical model of the fetal heart has been developed, using the hydraulic-electric analogy. The model is ba sed on a mechanical hypothesis of parallel functioning of the right an d left ventricles, considered to have analogue elastance properties. T heir behaviour is equivalent to that of a single ventricle ejecting an equivalent blood volume of 7 ml in the aorta. The characterisation of the equivalent ventricle is based on the determination of a set of fo ur parameters (E-max, V-0, k(v) and P-0) representing the maximum vent ricle contractility, a reference volume, and volume and pressure const ants, respectively. The model proposed is validated by studying the ef fects of preload and afterload variations on the fetal heart work, and by comparing the numerical results with literature and measured data. The model constitutes the first step towards a global model of the ca rdiovascular system of the human fetus.