Regional myocardial blood flow measurement with radioactive microspheres in dogs with myocardial ischemia

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In order to evaluate the radioactive microsphere techniqueused in our laboratory for measuring regional myocardial blood flow (RMBF) in dogs with myocardial ischemia, simultaneous blood flow measurements with three different nuclide (¹⁴¹Ce, ⁵¹Cr or ¹¹³Sn) -labeledm icrospheres were performed after coronary artery occlusion. There were excellent correlations between all paired RMBF values in 80 samples. The linear regression lines were expressed as: ⁵¹Cr=1.09x ¹⁴¹Ce-0.02 (r=0.996, SEE=0.06) ; ¹¹³sn=0.99x ¹⁴¹Ce+ 0.01 (r=0.997, SEE=0.05); ¹¹³Sn=0.90x ⁵¹Cr + 0.03 (r=0.991, SEE=0.08). The duplicate variability ranged from 5.5±0.7 to 9.9±1.1%. When RMBF was measured before and after ntravenous administration of nipradilol (0.2 mg/kg), a new beta-blocker, in a dog with myocardial ischemia, RMBF fell in the normal zone (23.6±1.6%), and did not change in the severely ischemiczone. Thus, this study demonstrated that RMBF can be measured accurately and repeatedly with radioactive microspheres in dogs with regional myocardial ischemia.