MYOCARDIAL BLOOD-FLOW AS MEASURED BY FRACTIONAL UPTAKE OF RB-84 AND MICROSPHERES

Abstract

Under conditions of varying flow rates, total myocardial blood flow, measured by fractional uptake of 84Rb, using a coincidence counting system, was compared with myocardial flow measured by microspheres (15 .+-. 5 .mu.m). The methods were compared in 47 open-chested dogs: 17 during control, 10 following 5 min of ligation of left anterior descending coronary artery, 5 following i.v. isoproterenol, 6 following ligation and isoproterenol, and 9 after ligation plus dipyridamole. Regional flows by 84Rb and by either 141Ce or 51Cr microspheres were also compared for left ventricle, and for nonischemic posterior wall, which served as a reference area, and for anterior wall with ligation of left anterior descending artery in the same preparations. There were no significant differences in total or regional flow measured by the 2 methods, nor in the estimate of ischemic area size. Measurement of myocardial blood flow by fractional uptake of a K analog is a reliable method in the presence of ischemia and drug intervention. The inequalities of extraction ratio that occur with differing flow rates probably do not invalidate fractional-uptake methods over the flow ranges examined.