[Mathematical formula for calculating ventricular ejection volume by changes in intracardiac electric conductivity (author's transl)].

In the present paper a formula appropiate to stroke volume estimation in the experimental animal is presented. Based in the indicator concentration difference during the two diastoles which follows the indicator injection on the ventricle chamber, the electric conductivity through impedance recording indicates these concentration. Appropiate procedures and a calibrating scale are used in order to obtain these two concentrations. From the stroke volume which appears as changes in impedance measured between a pair of electrodes located at the apex and base of the ventricle and the data obtained through the formula, the cardiac output and ventricular volume can be calculated.