Analysis of coronary hemodynamics in exercise by T1-201 scintigraphy: examination of rates of change of cardiac output, myocardial blood flow distribution, coronary blood flow and coronary vascular r...

Abstract:  From our observation that initial distribution of 201T1 in tissue is mainly dependent on blood flow distribution, we designed the method to obtain the rates of change of coronary blood flow and coronary vascular resistance and applied it to the analysis of coronary hemodynamics in patients with ischemic heart disease during submaximal exercise. We measured the rates of change of cardiac output (delta CO) and myocardial blood flow distribution (delta Fract ) in two occasions by the sequential two injections of T1, and obtained the rate of change of coronary blood flow (delta Flow) from delta CO and delta Fract . Using the rate of change of mean blood pressure, we calculated also the rate of change of coronary vascular resistance (delta CVR). The initial components of histograms of the right ventricle by the first and second injections of T1 were fitted into gamma function curve. S1 and S2 were the areas bounded by the curve and baseline of the first and second injections, and then the cardiac output ratio was estimated by R X S1/S2, where R was the dose ratio measured by another camera system. The five min count rates on the myocardium by the first (H1) and second (H2) injections of T1 were calculated five min after the injection. H2 was approximately H1 X R in the same condition of T1 injection but H2 was not equal to H1 X R, when the T1 injection was done in the different loading condition. Therefore the rate of change of myocardial blood flow distribution was calculated as delta Fract = (H1 X R-H2)/H2.(ABSTRACT TRUNCATED AT 250 WORDS)