Altered Contractile Response in Neonatal Myocardium to Citrate-Phosphate-Dextrose Infusion

The clinical use of citrate-phosphate-dextrose during blood-product transfusion is known to affect ionized calcium levels and can result in depression of myocardial contractility. The immature heart appears to have an intrinsic reduction in contractile state compared with the adult heart and may be more dependent on transsarcolemmal calcium flux for regulation of contraction. The myocardial contractile response to citrate infusion was compared in neonatal and adult rabbit hearts using clinically comparable citrate-phosphate-dextrose concentrations. Isovolumic left ventricular pressures were monitored in an isolated, crystalloid-perfused heart model before, during, and after 15 minutes of citrate-phosphate-dextrose infusion. Developed pressure decreased 42.1±4.9%o from control within 1 minute in the neonatal group versus 24.3 ±4.3% in the adult group (p<0.02). The effect on diastolic function was paradoxical in the neonate with a 43.1±11.9% increase in end-diastolic pressure compared with a 9.7±7.8% decrease in the adult (p<0.01). These results indicate that the neonatal heart appears more sensitive to the myocardial effects of citrate infusion with impairment of both systolic and diastolic function. The decreased ventricular compliance in the neonate with citrate-phosphatedextrose suggests that the myocardial effects may not be simply due to changes in ionized calcium concentration.