Measurement of Cardiac Output from Precordial Dilution Curves Using a Radioisotope : Special Conference on Advances in Methods of Diagnosis for Cardiac Diseases with Special Reference to Applications of New Techniques and Instruments

Abstract

In 124 subjects consisting of normal controls and patients with various diseases, 203 determinations of cardiac output were performed by precordial dilution technic using I¹³¹ labeled human serum albumin. 1) Our standard technic was determined to direct the scintillation detector toward the apex of the heart from the left lateral to see the left heart predominantly and to take a blood specimen for calibration 5 minutes after the RISA injection, since the values obtained under these conditions revealed the best approximation to those obtained by direct arterial sampling method. 2) The values determined by our standard technic demonstrated a satisfactory reproducibility and a reasonable agreement with those determined by Fick method. Superiority of the digital type recording to the conventional analog ratemeter recording was described. 3) Orthostatic decrease in cardiac output was more marked in patients with neurocirculatory asthenia and in those with hyperthyroidism than in control cases. 4) After lifting the legs in recumbent position, cardiac output decreased in some patients with heart disease, while it remained unchanged in control cases and slightly increased in patients with hyperthyroidism. 5) Aminophylline increased the cardiac output in patients with heart failure, but not in control cases and in patients with compensated heart disease. Cedilanid increased the cardiac output in one patient with heart failure but no significant changes were found in the other patients and in control cases within a relatively short period of observation.