MEASUREMENT OF THE STROKE VOLUME OF THE HUMAN HEART FROM ROENTGENOGRAMS; SIMULTANEOUS ROENTGENKYMOGRAPHIC AND ACETYLENE-REBREATHING EXPERIMENTS

Abstract

A method was described in which the vol. stroke of the human heart was estimated from measurements of the areas of the systolic and diastolic outlines of the heart in the frontal position on a roentgenkymographic film. Roentgenkymograms were made simultaneously with acetylene rebreathing expts. The results from 25 expts. on 16 normal subjects fitted the equation: Stroke vol. = 0.64(1.45 area diastole -1.45 area systole). The avg. difference between the methods was [plus or minus] 5.1% and the greatest differences were +10.7 and -10.2%, referred to the acetylene method as standard. Similar results were obtained with patients with circulatory abnormalities (myxedema, nephritis, hypertension) so long as no valvular defects were present. Patients with valvular leaks (mitral insufficiency, aortic regurgitation) always had stroke vols., measured by the kymograph, which were larger than the true stroke volume and this discrepancy was parallel to the best judgment of the leak from clinical studies. Comparison of results from the two methods gave a quantitative measure of the valvular defect.