Y.E. Kirpichenko, D.P. Timohin, S.I. Schookin

The creation of additional non-invasive techniques to improve the accuracy of such important biomechanical parameters of the heart as stroke volume and ejection fraction is an important task. One such method is the method of precardiac impedance mapping. For research a multichannel hardware-software complex has being used, it allows measuring impedance by using tetrapolar technique with 30 channels. In the problem of the heart contours determination the general interest is resulted from impedance signals containing information about the movements of the border areas of the heart. These borders are the left and right ventricles, valve area and cardiac apex. During the impedance mapping procedure we obtain pulse and basic component of impedance. Calculated by means of collected data area of the heart projection on the thorax are recalculated in volume. To take into account for the walls and the actual geometry of the ventricles it is necessary to calculate sphericity index of the heart. For conversion of volume change in stroke output and ejection fraction for each cardiac cycle anchor points of haemodynamic phases were used. The results of the experimental data showed that the numerical values of the stroke volume and ejection fraction obtained by the change in impedance contours of the projection of the heart, close to the estimates of these parameters by using MRI technique.