Effect of Intravascular Isotope Content on the Isotopic Determination of Coronary Collateral Blood Flow

Abstract

Simultaneous determinations of myocardial blood volume (using I¹³¹-PVP), myocardial blood flow (using H³₂O), and coronary collateral myocardial blood flow (using retrograde flow) were made in dogs after left circumflex artery ligation. Intravascular H³₂O content at the end of the H³₂O infusion was calculated as the product of myocardial blood volume and the final arterial H³₂O concentration. When correction is made for intravascular H³₂O content the resulting flow measured by H³₂O is nearly identical to the retrograde flow. These results indicate that radioactive isotopes can be used to measure blood flow if correction is made for the intravascular isotope content. The identity of corrected H³₂O flows with retrograde flows also indicates the applicability of isotopic methods for the measurement of coronary collateral blood flow.