[Radioisotope measurement of left ventricular ejection fraction. Comparison with results of cineangiocardiography].

The combination of radiocardiography with scintigraphy of the cavities of the heart allows us to calculate the effective systemic ejection fraction. The systolic volume effectively ejected into the systemic circulation is obtained from radiocardiography using Stewart-Hamilton's principle. It is correlated with the left ventricular end-diastolic volume as calculated by planimetry on the scintigraphic record of the cavities of the heart, making due allowance for the geometrical axis of the heart. The ejection fraction measured by this isotope method has been compared with the ejection fraction measured by selective left ventricular cineangiography, both measurements being carried out at an interval of less than 48 hours in 100 patients without valvular disease. The results show an excellent correlation between the two methods (r = 0.94). In the 15 cases where the haemodynamic status of the ventricule appeared to be normal, the ejection fraction meastured by the two techniques was 0.65 +/- 0.04 and 0.66 +/- 0.04 respectively. In those patients with valve disorders with incompetence, the effective systemic ejection fraction is always lower than the total ejection fraction given by cineangiography. The difference corresponds with the fraction of the blood volume which is regurgitated.