G Johnson1, D K Glover, C B Hebert, R D Okada. 1. William K. Warren Medical Research Institute, University of Oklahoma College of Medicine and Cardiology of Tulsa.
Abstract
UNLABELLED: The purpose of the current study was to determine whether teboroxime clearance kinetics are useful in differentiating the severity of coronary artery flow restriction. METHODS: Groups of dogs received stenoses of the left circumflex coronary artery as follows: nine dogs received a mild-to-moderate stenosis (Group 2) and eleven dogs received severe stenoses (Group 3). In three control dogs (Group 1), there was no stenosis. Using miniature cadmium-telluride radiation detectors, myocardial teboroxime activities were continuously monitored in both the control and stenosed zones following dipyridamole infusion. RESULTS: A significant difference in fractional myocardial clearance between the control zones (0.69 +/- 0.01, n = 26) versus mild-to-moderate (0.61 +/- 0.06, p < 0.05, n = 9) and severe (0.57 +/- 0.03, p < 0.01 versus control, p < 0.05 versus mild-to-moderate, n = 11) flow-restricted zones was observed over a 1-hr period. Significant differences between normal and both stenosed zones became apparent after 7 min of clearance. Significant differences in myocardial clearance between mild-to-moderate and severe groups were detected within 15 min. CONCLUSION: Thus, in this canine model using dipyridamole, miniature probe-determined teboroxime myocardial clearance can differentiate among normal myocardium, myocardium distal to a mild-to-moderate stenosis and myocardium distal to a severe stenosis.
UNLABELLED: The purpose of the current study was to determine whether teboroxime clearance kinetics are useful in differentiating the severity of coronary artery flow restriction. METHODS: Groups of dogs received stenoses of the left circumflex coronary artery as follows: nine dogs received a mild-to-moderate stenosis (Group 2) and eleven dogs received severe stenoses (Group 3). In three control dogs (Group 1), there was no stenosis. Using miniature cadmium-telluride radiation detectors, myocardial teboroxime activities were continuously monitored in both the control and stenosed zones following dipyridamole infusion. RESULTS: A significant difference in fractional myocardial clearance between the control zones (0.69 +/- 0.01, n = 26) versus mild-to-moderate (0.61 +/- 0.06, p < 0.05, n = 9) and severe (0.57 +/- 0.03, p < 0.01 versus control, p < 0.05 versus mild-to-moderate, n = 11) flow-restricted zones was observed over a 1-hr period. Significant differences between normal and both stenosed zones became apparent after 7 min of clearance. Significant differences in myocardial clearance between mild-to-moderate and severe groups were detected within 15 min. CONCLUSION: Thus, in this canine model using dipyridamole, miniature probe-determined teboroxime myocardial clearance can differentiate among normal myocardium, myocardium distal to a mild-to-moderate stenosis and myocardium distal to a severe stenosis.