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Effects of correction of hypocalcemia on cardiac function in the newborn lamb
A J Moon1, J M Milstein, B W Goetzman
1Division of Neonatology, Department of Pediatrics, University of California, Davis, Calif 95616, USA.
Insights
Correcting hypocalcemia in newborn lambs did not alter cardiac contractility. However, calcium administration may influence diastolic or early systolic function, suggesting potential effects on neonatal cardiac performance.
Area of Science:
- Neonatal physiology
- Cardiovascular research
- Pediatric cardiology
Background:
- Hypocalcemia is common in neonates and can affect cardiac function.
- The precise impact of calcium correction on neonatal hemodynamics and contractility remains incompletely understood.
Purpose of the Study:
- To investigate the effects of correcting hypocalcemia on cardiac function in a neonatal lamb model.
- To evaluate changes in hemodynamic variables and cardiac contractility following calcium administration.
Main Methods:
- Neonatal lambs were induced with hypocalcemia using intravenous ethyleneglycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA).
- Cardiac contractility was assessed using end-systolic elastance and dP/dt(max).
- Hemodynamic variables including systemic vascular resistance, cardiac output, and heart rate were monitored.
Main Results:
- End-systolic elastance, a load-independent measure of contractility, showed no significant change with calcium correction.
- dP/dt(max), a load-dependent index, increased with calcium administration, accompanied by a decrease in end-diastolic volume.
- Systemic vascular resistance, cardiac output, and heart rate remained largely unchanged.
Conclusions:
- Neonatal cardiac contractility appears insensitive to ionized calcium levels in this lamb model, potentially reflecting cardiac immaturity.
- Calcium administration may influence diastolic or early systolic function in hypocalcemic neonates.
- Further research is needed to fully elucidate the role of calcium in neonatal cardiac regulation.
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.