Effects of Correction of Hypocalcemia on Cardiac Function in the Newborn Lamb

Abstract

The effect of correction of hypocalcemia on cardiac function in the neonate is unclear. Therefore, we evaluated changes in hemodynamic variables and cardiac contractility in a hypocalcemic neonatal lamb model. Baseline serum ionized hypocalcemia was induced via chelation with intravenous EGTA. Cardiac contractility, measured as end-systolic elastance, did not change with correction of hypocalcemia in this model. In contrast, the variable dP/dt_max, a load-dependent index of contractility, showed an increase with calcium administration while the end-diastolic volume decreased, suggesting that diastolic function or early systolic function had changed. Systemic vascular resistance, cardiac output, and heart rate did not change significantly with correction of hypocalcemia. The results of this study suggest that in our newborn lamb model, cardiac contractility is insensitive to ionized calcium and may reflect cardiac immaturity, but that there may be an effect of calcium administration on diastolic or early systolic function.

Changes in cardiac TRPM6 and TRPM7 expression during late gestation and transition to extra-uterine life in preterm and term piglets

“…The role of extracellular Ca 2+ has already been well studied in neonatal infants, as serum Ca 2+ concentration is simple to measure. The development of extracellular hypocalcaemia in low birth weight infants is relatively common (~30%) [32], but this has been shown to have little impact on cardiac function and morbidity [33,34]. The role of intracellular Ca 2+ concentration has not been as well investigated, as the Ca 2+ concentration inside a cell cannot be measured in live infants.…”