Simultaneous measurement of total and nutritional coronary blood flow in dogs.

Significant correlation has been shown between the severity of coronary disease and level of coronary blood flow as measured by the rubidium coincidence technique. Contrary to the commonly expressed view, however, the rubidium coincidence method does not evaluate nutritional flow, but estimates total coronary blood flow (CBFT). An equation is derived that does evaluate nutritional flow (CBFN), allowing simultaneous measurement of total and nutritional flow. The extraction ratio of the total body (ERTB) relative to the extraction ratio of the heart (ERr) was measured in a total of 21 dogs by employing the relative uptake of labeled microspheres and diffusible ions, 86Rb and 131Cs. CBFT, measured with a bolus injection of 86Rb or .31Cs, was compared with total flow measured by the microsphere technique in dogs, with and without drug administration (norepinephrine, isoproterenol, nitroglycerin). These studies showed that while rubidium gives accurate mean values of total flow (4% mean difference, r 0.92) individual estimates may be in error by