Magnesium supplementation during cardiopulmonary bypass to prevent junctional ectopic tachycardia after pediatric cardiac surgery: A randomized controlled study

Presented and awarded at the European Symposium of the Pediatric Cardiac Intensive Care Society (March 2008) (Young Investigator Award).

Received 30 September 2008; received in revised form 27 May 2009; accepted 23 July 2009. published online 12 October 2009.

Objectives

We analyzed the role of magnesium sulfate (MgSO4) supplementation during cardiopulmonary bypass in pediatric patients undergoing cardiac surgery, assessing the incidence of hypomagnesemia and the incidence of junctional ectopic tachycardia.

Methods

We performed a randomized, double-blind, controlled trial in 99 children. MgSO4 or placebo was administered during the rewarming phase of cardiopulmonary bypass: group 1, placebo group (29 patients); group 2, 25 mg/kg of MgSO4 (30 patients); and group 3, 50 mg/kg of MgSO4 (40 patients).

Results

At the time of admission to the cardiac intensive care unit, groups receiving MgSO4 had significantly greater levels of ionized magnesium (group 1, 0.51 ± 0.07; group 2, 0.57 ± 0.09; group 3, 0.59 ± 0.09). Hypomagnesemia before bypass was common (75%–86.2%) and not significantly different among the groups. The proportion of hypomagnesemia decreased significantly at admission to the cardiac intensive care unit in groups receiving MgSO4 (group 1, 77.8%; group 2, 63%; group 3, 47.4%). Patients receiving placebo (group 1) had a significantly greater occurrence of junctional ectopic tachycardia than groups receiving MgSO4 (group 1, n = 5 [17.9%]; group 2, n = 2 [6.7%]; group 3, n = 0 [0%]). Age (<1 month), Aristotle score (>4), and history of cardiac failure were associated with junctional ectopic tachycardia. None of the patients with those characteristics in group 3 had junctional ectopic tachycardia. No association was found between study groups and the Pediatric Risk of Mortality score or length of stay in the cardiac intensive care unit.

Conclusions

Supplementation with MgSO4 during cardiopulmonary bypass seems to reduce the incidence of hypomagnesemia and junctional ectopic tachycardia at admission to the cardiac intensive care unit. This effect seems to be dose related.

CTSNet classification: 1, 16, 20, 21

Abbreviations and Acronyms: CICU, cardiac intensive care unit, CPB, cardiopulmonary bypass, iMg, ionized magnesium, JET, junctional ectopic tachycardia, MgSO4, magnesium sulfate, PRISM, Pediatric Risk of Mortality

a Department of Pediatrics, Heart Center, Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, Pa

b Department of Medicine, Department of Biostatistics, University of Pittsburgh, Pittsburgh, Pa

c Department of Medicine, Department of Epidemiology, University of Pittsburgh, Pittsburgh, Pa

d Department of Anesthesiology, Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, Pa

e Department of Cardiothoracic Surgery Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, Pa

f Department of Critical Care Medicine, Division of Cardiac Intensive Care, Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, Pa

Address for reprints: Ricardo Munoz, MD, FAAP, FCCM, Chief, Cardiac Intensive Care Division; Director, Cardiac Recovery Program, Children's Hospital of Pittsburgh of UPMC Heart Center, 3705 Fifth Ave, Pittsburgh, PA 15213.

Disclosures: Partially supported by funds from the Nova Biomedical Corporation (Waltham, Mass).

PII: S0022-5223(09)01021-6

doi:10.1016/j.jtcvs.2009.07.064

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