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  • Title: Effects of high plasma epinephrine and Ca2+ concentrations on neonatal myocardial function after ischemia.
    Author: Caspi J, Coles JG, Benson LN, Herman SL, Augustine J, Tsao P, Brezina A, Kolin A, Wilson GJ.
    Journal: J Thorac Cardiovasc Surg; 1993 Jan; 105(1):59-67. PubMed ID: 8419710.
    Abstract:
    Administration of catecholamines to newborn infants may potentiate reperfusion injury because of increased transsarcolemmal Ca2+ influx and the presence of less developed sarcoplasmic reticulum in the immature hearts. We investigated the effect of administration of epinephrine (1.5 micrograms/kg per minute for 120 minutes) before ischemia and modified serum ionized Ca2+ concentrations in the cardioplegic solution and perfusate on postischemic left ventricular systolic and diastolic function in 25 piglets (5 to 7 days old) undergoing 90 minutes of cold blood cardioplegic arrest. The piglets were divided into four groups; Ca2+ 1.2 mmol/L, group A (n = 6), Ca2+ 0.25 mmol/L, group B (n = 6), Ca2+ 1.2 mmol/L and epinephrine, group C (n = 6), Ca2+ 0.25 mmol/L and epinephrine, group D (n = 7). Left ventricular function was assessed by a conductance catheter in the left ventricle measuring end-systolic and end-diastolic pressure-volume relationships during transient vena caval occlusion. By analysis of covariance, only Ca2+ concentration was important in predicting ventricular function recovery after ischemia (p < 0.01). End-systolic elastance decreased in all groups after ischemia; the magnitude was significantly greater in the normal groups (51% versus 35%, p < 0.01). There was a significant increase in the chamber stiffness index after administration of epinephrine before ischemia (p < 0.05). Groups with low Ca2+ perfusate (B and D) had no change in chamber stiffness index after ischemia. In contrast, there was a significant increase in chamber stiffness in the normal Ca2+ groups with (C) or without (A) epinephrine after ischemia (p < 0.05). Adenosine triphosphate stores declined significantly in the normal Ca2+ groups--48% versus 18% in the low Ca2+ groups (p < 0.01). We conclude that low Ca2+ concentrations in the perfusate and cardioplegic solutions better preserve left ventricular function in the normal and in epinephrine-stressed neonatal heart after ischemia.
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