Effects of Infusion of Dopamine and Nitroprusside on Size of Experimental Myocardial Infarct

Abstract

Using a canine model for experimentally induced myocardial infarction via ligation of the left anterior descending coronary artery and using a stain for intracellular lactic dehydrogenase to directly measure the size of the infarct, we evaluated the influence of infusion of dopamine and sodium nitroprusside. Infusion of sodium nitroprusside (222µg/min) produced significant decreases in the mean blood pressure, total peripheral resistance, and left atrial pressure and reduced the volume of the infarct by 58 percent (P < 0.0025). The administration of dopamine (6µg/kg/min) significantly improved the cardiac index and lowered the systemic vascular resistance and left atrial pressure but did not affect the size of the infarct Administration of dopamine at a rate of 15µg/kg/min significantly increased the mean blood pressure and cardiac index and decreased the peripheral resistance and left atrial pressure. The histochemically determined volume of the infarct was reduced by 37 percent (P < 0.0025), but the hearts were very edematous and hemorrhagic. Therapy with nitroprusside appears to have promise in the active treatment of clinical myocardial infarction. The safe use of therapy with high doses of dopamine in patients with acute myocardial infarction must await further study. Using a canine model for experimentally induced myocardial infarction via ligation of the left anterior descending coronary artery and using a stain for intracellular lactic dehydrogenase to directly measure the size of the infarct, we evaluated the influence of infusion of dopamine and sodium nitroprusside. Infusion of sodium nitroprusside (222µg/min) produced significant decreases in the mean blood pressure, total peripheral resistance, and left atrial pressure and reduced the volume of the infarct by 58 percent (P < 0.0025). The administration of dopamine (6µg/kg/min) significantly improved the cardiac index and lowered the systemic vascular resistance and left atrial pressure but did not affect the size of the infarct Administration of dopamine at a rate of 15µg/kg/min significantly increased the mean blood pressure and cardiac index and decreased the peripheral resistance and left atrial pressure. The histochemically determined volume of the infarct was reduced by 37 percent (P < 0.0025), but the hearts were very edematous and hemorrhagic. Therapy with nitroprusside appears to have promise in the active treatment of clinical myocardial infarction. The safe use of therapy with high doses of dopamine in patients with acute myocardial infarction must await further study.