Redistribution of myocardial blood flow distal to a dynamic coronary arterial stenosis by sympathomimetic amines: Comparison of dopamine, dobutamine and isoproterenol

The effects of dopamine, dobutamine and isoproterenol on coronary hemodynamics, severity of stenosis, distal bed resistance and transmural myocardial perfusion gradients with radioactive microspheres were studied in dogs with a mild obstruction of the left circumflex coronary artery anesthetized with morphine-chloralose. Changes in transmural blood flow were related to the ratio of the diastolic aortic pressure-time Index to tension-time index (DPTI/TTI) and the ratio of the distal diastolic coronary pressure-time index to tension-time index (DDPT1/TTI). At doses of 5 gmg/kg per min, dopamine had no significant effect on DPTI/TTI, DDPTI/TTI or endocardial/epicardial flow ratio; however, dobutamine produced a slight decrease in this flow ratio and in DDPTI/TTI. At doses of 10 gmg/kg per min, both drugs produced a significant (p