A simple and rapid non-invasive radioisotope method to determine ventricular ejection fractions and cardiopulmonary transit times.

Ejection fractions and cardiopulmonary transit times were measured in 20 hospital patients by means of intravenously injected 99mTc-radiocardiography. Time activity curves from the regions of the whole heart, superior vena cava, right atrium, right ventricle, right lung, left atrium and left ventricle were drawn and analyzed by using the modified gamma function fitting method. The comparison between the ejection fractions determined from the whole heart curves and those from the ventricular curves shows a correlation coefficient of 0.93 for the right ventricle and of 0.90 for the left, although there was a systematic difference between the determinations. The analysis of the single ventricular curves gave about 10% higher values than those obtained from the whole heart curves. The cardiopulmonary parameters measured from the whole heart curves for 16 normal subjects the following results gave: right ventricular ejection fraction=0.57+/-0.08 left ventricular ejection fraction=0.62+/-0.08 pulmonary mean transit time=6.1+/-1.1 heart-beats intracardiac mean transit time=10.5+/-1.8 heart-beats right/left ventricular volume=1.10+/-0.09 These values agree closely with the data accumulated using more elaborate methods. The method presented here is simple to perform, it is non-invasive, time-saving, inexpensive, easy to analyze and suitable for exercising subjects and for bed-side measurements. Data assembly and analysis are easily automated so that results are obtainable immediately after measurements.