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

In order to evaluate the radioactive microsphere technique used 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)-labeled microspheres 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 intravenous 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 ischemic zone. Thus, this study demonstrated that RMBF can be measured accurately and repeatedly with radioactive microspheres in dogs with regional myocardial ischemia.