Effects of dobutamine and isoproterenol on systemic hemodynamics and myocardial metabolism in children after open heart surgery

: The purpose of this study is to know the effects of Dobutamine (DOB) and Isoproterenol (ISP) on the systemic hemodynamics and myocardial metabolism in the acute phase after open heart surgery in children. Twelve patients with congenital heart disease were administered 5 and 10 micrograms/kg/min (gamma) of DOB, then 0.005 and 0.01 gamma of ISP, and the systemic hemodynamic and metabolic data were taken before and after the administration of the drugs. DOB: DOB increased HR and SVI, so CI rose up markedly. The systolic, diastolic and mean blood pressure also rose up after both doses. CVP and PCWP were depressed at both dosage levels. SVRI and PVRI did not show an appreciable change. ISP: ISP increased HR, CI and systolic blood pressures significantly. On the other hand, SVRI, PVRI and PCWP were decreased at both dosage levels. Myocardial metabolism: The two drugs tested did not exhibit any effect on the progress of anaerobic myocardial metabolism. The myocardial oxygen uptake rate was decreased with DOB and ISP. These phenomena probably suggest that DOB and ISP dilate the coronary vascular bed. From the above data, the following effects can be expected by the use of each drug after open heart surgery in children; 1) powerful inotropic and chronotropic action by DOB, and 2) chronotropic action and after-load reduction by ISP.