Acute hemodynamic effects of dopamine, dobutamine, and isoproterenol in congested infants or young children with large ventricular septal defect.

We studied the acute hemodynamic effects of dopamine, dobutamine, and isoproterenol in infants and young children with large ventricular septal defect (VSD). Dopamine (5 micrograms/kg/min) had no significant hemodynamic effects. Dobutamine (5 micrograms/kg/min) administration resulted in modest increases in heart rate and systemic arterial pressure and a decrease in left atrial pressure. This drug decreased the pulmonary blood flow, and the pulmonary-to-systemic blood flow (Qp/Qs) ratio, although these changes were not statistically significant. Isoproterenol, infused at doses of 0.03 and 0.06 micrograms/kg/min, increased the heart rate and lowered left atrial pressure. Only the high dose of isoproterenol lowered systemic and pulmonary arterial pressure. The low dose infusion of this drug increased the pulmonary blood flow as well as the systemic flow, whereas the high dose infusion resulted in a decrease of the Qp/Qs ratio without an increase in the pulmonary blood flow. Right atrial pressure was lowered by dobutamine and the high dose of isoproterenol, but the mean change was only 1 to 2 mmHg. The difference of the effects among these catecholamines is due to their relative strength of action on the vascular bed and the myocardium. Although the doses and durations of the drug infusions were limited, these acute hemodynamic effects should be taken into account when they are to be given to congested infants and young children with large VSD.