Effects of correction of hypocalcemia on cardiac function in the newborn lamb

The effect of correction of hypocalcemia on cardiac function in the neonate is unclear. Therefore, we evaluated changes in hemodynamic variables and c ardiac contractility in a hypocalcemic neonatal lamb model. Baseline serum ionized hypocalcemia was induced via chelation with intravenous EGTA, Cardi ac contractility, measured as end-systolic elastance, did not change with c orrection of hypocalcemia in this model. In contrast, the variable dP/dt(ma x), a load-dependent index of contractility, showed an increase with calciu m administration while the end-diastolic volume decreased, suggesting that diastolic function or early systolic function had changed. Systemic vascula r resistance, cardiac output, and heart rate did not change significantly w ith correction of hypocalcemia, The results of this study suggest that in o ur newborn lamb model, cardiac contractility is insensitive to ionized calc ium and may reflect cardiac immaturity, but that there may be an effect of calcium administration on diastolic or early systolic function. Copyright ( C) 2000 S. Karger AG, Basel.